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Biomedical subjects

D J Hendrick

Publications and source records attributed to D J Hendrick.

17 recordsLinked to original sources
PubMed1992

A comparison of the speeds of action of salmeterol and salbutamol in reversing methacholine-induced bronchoconstriction.

We compared the speed of action of the long acting beta-agonist salmeterol with that of salbutamol in order to assess whether reported in vitro differences are likely to have clinical significance. We used methacholine tests to produce a standardized level of bronchoconstriction and then observed the rate of recovery of FEV1 towards baseline after the administration by metered dose inhaler of salmeterol 50 micrograms or salbutamol 200 micrograms--doses which are considered to have similar bronchodilator potency. Twenty asthmatic subjects participated, and a double-blind, randomized, cross-over study design was followed. Salmeterol showed a significantly slower speed of action with median recovery to 90% and 95% of the baseline FEV1 (pre-methacholine) occurring after 9.6 and 19.4 min, respectively, compared with 4.8 and 8.3 min, respectively, for salbutamol (P less than 0.01). These observations are consistent with in vitro findings and suggest that salmeterol is likely to be less satisfactory than salbutamol as a 'rescue medication' for the treatment of acute episodes of bronchoconstriction.

Adult↗
PubMed1992

The effect of GR32191 (a thromboxane receptor antagonist) on airway responsiveness in asthma.

Airway responsiveness to methacholine was measured in nine subjects (22-53 years, seven male) with chronic stable asthma. All subjects were taking inhaled beclomethasone (less than 1000 micrograms daily). The mean baseline FEV1 was 2.841 (77% of predicted) and the geometric mean PD20FEV1 was 31 micrograms. After a run-in period, the subjects were randomly allocated to two treatment periods with the specific thromboxane receptor antagonist GR32191, 40 mg four times daily for 3 weeks, and identical placebo capsules. A double-blind, placebo-controlled, cross-over design was employed with 4 weeks between the two treatment periods. Treatment with GR32191 did not result in any significant improvement in mean FEV1 (2.941 after placebo and 2.861 after GR3219; F7.71 = 1.02, P greater than 0.1) or PD20FEV1 (24.3 micrograms after placebo and 38.5 micrograms after GR32191; F7.71 = 0.59, P greater than 0.1). We conclude that thromboxane is not important in the maintenance of airway hyperresponsiveness in chronic asthma and that thromboxane receptor antagonists are unlikely to provide effective treatment for this group of patients.

Adult↗
PubMed1992

The origin of water and urea sampled at bronchoalveolar lavage in asthmatic and control subjects.

Bronchoalveolar lavage (BAL) urea has been advocated as a denominator that might allow for the dilution of the pulmonary epithelial lining fluid sampled at BAL, and so provide a meaningful method of expressing BAL data. We investigated the origin of water and urea sampled at BAL in five asthmatic and five control subjects using radiolabeled urea injected intravenously 5 min before BAL. Labeled BAL urea was found to be fully equilibrated with that in the bloodstream. A strong relationship was found between influx of radiolabeled water and radiolabeled urea from blood to BAL fluid, suggesting that urea sampled at BAL may be derived predominantly from an acute movement from the bloodstream into the BAL aspirate. We conclude that urea is an inappropriate denominator for the expression of BAL results, and that the fluid and solute dynamics that occur during BAL are both complex and variable.

Adult↗
PubMed1992

Calibration of aerosol output from the Mefar dosimeter: implications for epidemiological studies.

Standardized methods for the measurement of airway responsiveness may use the Mefar MB3 inhalation dosimeter to generate standard doses of methacholine aerosol. The manufacturer provides calibrated output data for every nebulizer, so that a standard output may be achieved by varying nebulization time. This output is, however, measured by weight loss (WL), which may over-estimate true aerosol output (AO) because of concomitant evaporation. We have used a chemical (fluoride) tracer method to measure AO directly from two batches of Mefar nebulizers (batch 1 n = 5, batch 2 n = 10) and compared results with manufacturer's quoted WL. Mean AO from batch 1 was 10.56 mg.s-1 (range 9.50-11.63, SD = 0.92 mg.s-1), and mean AO from batch 2 was 5.66 mg.s-1 (range 4.92-6.58, SD = 0.57 mg.s-1), implying that AO varied little within, but substantially between, the two nebulizer batches. Manufacturer's quoted WL does not reflect this near two fold difference: mean WL batch 1 = 14.0 mg.s-1 (range 13-15 mg.s-1); mean WL batch 2 = 11.1 mg.s-1 (range 11-12 mg.s-1). The median aerosol fractions (AO/WL) for batches 1 and 2 were 76% (range 65-83%) and 50% (range 43-60%), respectively. Similar results were obtained with our own measurement of weight loss. This implies that if the median nebulizers of batches 1 and 2 were calibrated (as recommended) by the manufacture's WL to deliver a presumed 100 micrograms methacholine dose, the actual doses delivered would be 76 micrograms and 50 micrograms, the range for all 15 nebulizers being 43-83 micrograms.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1978

Budgerigar-fancier's lung: the commonest variety of allergic alveolitis in Britain.

A questionnaire survey of 1005 consecutive attenders at four outpatient clinics yielded 117 (12%) budgerigar fanciers (exposed to budgerigars- known in North America as parakeets-for at least three months) and 296 (29%) former fanciers. Twnety had precipitins to budgerigar serum or droppings or both, and 10 of these together with 39 precipitin-negative patients reported undue breathlessness on exertion during exposure to buderigars. These 59 patients were investigated further, seven completing a series of inhalation provocation tests with budgerigar antigens designed to confirm or exclude budgerigar-fancier's lung (BrFL). Typical positive responses were obtained from four current and one former fancier. The prevalence of confirmed BrFL among the 11n current budgerigar fanciers was 3.4% (four cases). This was biased, however, by the inclusion of one patient whose attendance at the surveyed clinic was attributable to the disease. With the exclusion of this patient, confidence limits suggested that the true prevalence of BrFL among current budgerigar fanciers in the general population lies between 0.5% and 7.5%, which is similar to the prevalence of farmer's lung in farm workers. In view of the enormous population at risk, however, this implies that BrFL rather than farmer's lung is by far the commonest type of allergic alveolitis in Britain.

Adolescent↗
PubMed1978

Precipitins to different avaian serum antigens in bird fancier's lung and coeliac disease.

Precipitins to avian serum antigens have been found in the sera of bird fanciers and, until now, they have been considered strong supporting evidence for a clinical diagnosis of bird fancier's lung (BFL). We now report that 35% of patients with coeliac disease, none of whom had recently kept a bird, had precipitins against an avian serum antigen common to all the avian species tested, but which was distinct from the antigens usually associated with BFL. This antigen was a component of hen egg yolk but not of bird droppings. In patients with BFL the antibody response results from inhaled antigens in the bird droppings, whereas the antibody response in patients with coeliac disease probably results from eating uncooked or soft-boiled eggs.

Adult↗
PubMed1978

Is bird fancier's lung associated with coeliac disease?

Precipitin responses to different avian serum antigens occur in bird fancier's lung (BFL) and coeliac disease. Failure to distinguish between them could encourage an erroneous diagnosis of BFL in patients with coeliac disease, and the recent suggestion that these two disorders are strongly associated may be questioned, partly for this reason. In the present study small bowel biopsy specimens were obtained from 12 of a series of 14 patients proved to have BFL by inhalation provocation tests. None was suggestive of coeliac disease. Of a further 61 patients with biopsy-proved coeliac disease, seven were found to be exposed currently and 33 formerly to birds. As a result of clinical evaluation, BFL was considered a possible cause of undue breathlessness reported by three of the current bird fanciers only, and all underwent inhalation provocation tests. One alone gave positive results. We conclude that if a real association does exist between these two disorders, its clinical importance has been greatly exaggerated.

Alveolitis, Extrinsic Allergic↗
PubMed1977

Occupational formalin asthma.

Hypersensitivity to formalin used to sterilise artificial kidney machines was shown by inhalation provocation tests to be responsible for attacks of wheezing accompanied by productive cough in two members of the nursing staff of a haemodialysis unit. Three further members of the staff of 28 who were continually exposed to this substance occupationally had developed similar recurrent but less frequent episodes since joining the unit. Two underwent inhalation provocation tests with formalin which did not reproduce these symptoms. Single episodes of these symptoms had been noted by three additional staff members so that altogether eight (29%) had experienced attacks described as bronchitic since becoming exposed to formalin. We suggest that, while exposure to formalin did not seem to be directly responsible in all cases, it might have increased susceptibility to other provoking agents or induced a hyper-reactive responsiveness of the airways. The responses observed in the two nurses after inhalation provocation tests with fromalin were predominantly of airways obstruction. Wheezing began between two and three hours after exposure, and peak expiratory flow rates fell maximally by approximately 50%. Reactions persisted for 10 hours to 10 days depending on the exposure dose. A productive cough was a prominent feature. The sputum appeared to be mucopurulent, but culture produced a scanty growth of Haemophilus influenzae only, together with upper respiratory tract commensals. The cellular content was not homogeneous, neutrophil leucocytes and eosinophil leucocoytes variably dominating. Variable responses of neutrophil and eosinophil leucocytes were also seen in the peripheral blood.

Adult↗
PubMed1976

Chest pain in the presentation of sarcoidosis.

The cases of six patients are reported illustrating that chest pain may be a prominent feature of sarcoidosis. It may be severe and be the chief presenting symptom. In the cases described it was mostly retrosternal and had few consistent aggravating factors. In each case there was bilateral hilar lymph node enlargement and it is suggested that htis was chiefly responsible for this relatively uncommon symptom of sarcoidosis. It is also suggested that undue persisting pain may respond to corticosteroid administration.

Adrenal Cortex Hormones↗
PubMed1976

Bakers' asthma.

Bronchial provocation tests by "occupational" exposure to flour provoked dual asthmatic reactions accompanied by rhinitis in two atopic bakers engaged in the manufacture of bread and pies. Ingestion tests with uncooked flour produced no reactions. Skin prick tests with aqueous extracts of flour produced positive immediate reactions in both bakers, and negative reactions in nine of ten atopic asthmatic control subjects with no occupational exposure to flour. Intracutaneous tests, performed in one precipitin negative baker, gave dual responses. Precipitating antibodies to an aqueous extract of flour were found in the unconcentrated serum of the other baker, and not in ten control subjects.

Adult↗
PubMed1975

An analysis of skin prick test reactions in 656 asthmatic patients.

Of 656 asthmatic patients referred specifically for allergy assessments, 544 (84 percent) gave positive immediate skin prick tests to at least one of 22 common allergens used routinely. Comparison of these skin test positive patients with the 102 (16 percent) who were skin test negative showed a number of significant differences. The majority of the skin test positive patients (52 percent) were less than 10 years old at the time of onset of the asthma, whereas, of the skin test negative patients, 56 percent were aged over 30 years at the time of onset. Seventy per cent report rhinitis compared with 48 per cent of the skin test negative patients, and 29 per cent reported infantile eczema compared with 9 per cent. Symptoms attributed to house dust, pollens, and animals were noted two to three times more frequently by the skin test positive patients, while corticosteroid drugs had been used more commonly by the skin test negative patients (45 percent compared with 35 percent). No significant differences were observed with the other factors studied, namely, history of urticaria or angio-oedema, family history of "allergic" disease, and awareness of sensitivity to foods, aspirin or penicillin. Prick test reactions in the skin test positive patients were most commonly seen to house dust or the acarine mite, Dermatophagoides farinae (82 percent), followed by pollens (66 percent), animal danders (38 percent), foods (16 percent), Aspergillus fumigatus (16 percent), and other moulds (21 percent). There was a highly significant association of positive history with positive prick test for all allergens studied.

Adrenal Cortex Hormones↗
PubMedDate not supplied

Design characteristics for drug nebulizers.

Drug nebulizers should be designed to produce an aerosol which efficiently targets drug to the respiratory tract. In this article we review the basic principles of aerosol generation from both jet and ultrasonic nebulizers, and the factors governing respiratory tract penetration and deposition. We review methods for accurate measurement of aerosol dose and size, with emphasis on evaporative effects and the implications to drug nebulizer design. We identify three forms of drug aerosol waste attributable to: generation of non-respirable aerosol, losses to the environment, and dead volume solution; and we consider how each may be minimized through good nebulizer design. Finally, we compare the relative merits of jet and ultrasonic nebulizers, and conclude by predicting a new trend in future drug nebulizer therapy.

Aerosols↗