Biomedical subjects
Publications and source records attributed to D Ahmad.
Although amyloidosis of the respiratory tract is well recognized, pleural involvement is very rare with only two cases being reported in the past. We report a case of primary amyloidosis with pleural effusion and suggest that pleural involvement and pleural effusion be added to the classification of pulmonary amyloidosis, and that amyloidosis be added to the list of causes of a pleural effusion.
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The effects on standing heart rate and respiratory function of two relatively selective beta 1-adrenoceptor antagonists, metoprolol and bevantolol, were compared in a double-blind, randomized, crossover study of 16 patients with asthma. After control observations on 2 separate days, the patients received approximately equivalent cardiac beta-adrenoceptor antagonist doses of metoprolol, 12.5, 25, 50, and 100 mg, and bevantolol, 18.75, 37.5, 75 and 150 mg, at intervals of 2 hours. Dosing was stopped if symptoms warranted or if there was a fall of greater than or equal to 20% in the forced expiratory volume in 1 second. In general, the cumulative dosing regimen proved a safe and effective means of assessing bronchial responsiveness to these beta-blockers in asthma, but one patient had to be dropped from the study because of severe bronchoconstriction after the first dose. Of the 15 patients studied who were taking both drugs, seven patients were withdrawn prematurely. In these seven patients, the average maximum tolerated cumulative doses were 45.5 mg bevantolol and 26.8 mg metoprolol, doses that are much lower than those usually required for therapeutic activity. The respiratory response to either drug could not be predicted.
A patient with status asthmaticus deteriorated while receiving conventional therapy including mechanical ventilation. She failed to respond to the inhalation of enflurane but had a beneficial response to halothane. Her subsequent course was complicated by a prolonged metabolic encephalopathy which was associated with an elevated plasma bromide level from the metabolism of halothane.
Were aminophylline to improve mucociliary function, it might prove useful in the management of irreversible airflow limitation. Eight subjects with irreversible airflow limitation due to emphysema inhaled an aerosol of 99mTc sulphur-colloid particles on each of 2 days. On day 1 aminophylline was administered intravenously, while on the other nothing was given. Particle clearance was measured by recording posterior gamma-camera images sequentially over a 24 h period. No significant differences were recorded between aminophylline and control studies, but there were marked variations in clearance between study days and between individuals. These differences were compatible with the known effects of airways obstruction and breathing pattern on the sites of particle deposition within the bronchial tree. The latter factors appeared to exert a far greater influence on the observed mucociliary clearance than did aminophylline.
The effects on ventilation of the non-selective beta-blocker propranolol, and the relatively cardioselective beta-blocker, metoprolol, were compared in a randomized single-blind crossover study in 16 patients with asthma, bronchitis and emphysema (American Thoracic Society criteria). Group I had "fixed" airways disease with less than 20% improvement in FEV1 following inhaled salbutamol 5 mg by nebuliser. Group II had "reversible" obstruction, greater than 20% improvement. Bronchodilator therapy was withheld for 24 h with the exception of aerosols which were permitted until 12 h before study. After control observations on each of 2 study days, each patient received cumulative doses of propranolol (maximum 170 mg) and metoprolol (maximum 187.5 mg). Ventilatory function (FEV1, FVC, FEV1%) was assessed at 0, 2, 4, 6 and 8 h. In Group I, 2 patients were unable to complete the study. One patient became dizzy with propranolol 70 mg but tolerated metoprolol 187.5 mg. One patient developed wheeze with propranolol 15 mg but tolerated metoprolol 187.5 mg. Metoprolol was tolerated in all 8 patients with "fixed" disease, although FEV1 was reduced by more than 30% in 1 patient. Three patients in Group II did not complete the study because of wheezing following propranolol 10 mg, metoprolol 37.5 mg; propranolol 17.5 mg, metoprolol 37.5 mg; propranolol 45 mg, tolerated metoprolol 187.5 mg respectively. Wheezing responded in all cases to inhaled isoprenaline. The response to either propranolol or metoprolol was unpredictable in patients with "reversible" disease. When wheezing occurred in this group, it developed following small, potentially subtherapeutic doses of each drug. Although metoprolol was better tolerated, the practical benefit of cardioselectivity in those patients with reversible airways disease was negligible.
We investigated the regional deposition in the lungs, of an inhaled submicron aerosol at rest and during exercise in 13 normal volunteers of whom 5 were cigarette smokers. The degree of exercise (VO2 approximately 2 L/min) was chosen to simulate moderately heavy physical labour. Tracheobronchial and alveolar components of deposition were measured by comparing images immediately after inhalation of aerosol and 24 h later when mucociliary clearance was complete. At rest almost all deposition was alveolar (97%). The increase in total deposition on exercise was of similar order to the increase in ventilation. On exercise regional alveolar deposition became more even, although basal still exceeded apical deposition. Tracheobronchial deposition on exercise was increased in all zones but particularly in the upper zones, thereby contrasting with the base to apex gradient of parenchymal deposition. These changes were exaggerated in the smokers. The increased upper zone tracheobronchial deposition may have implications in regard to the pathogenesis of diseases caused by the inhalation of dusts and fumes.
We studied regional changes in ventilation and aerosol deposition after histamine challenge in six patients with asthma and two with rhinitis and a history of wheezing. All were known to have bronchial hyperreactivity and all showed an increased response to histamine. Ventilation and aerosol deposition studies, using xenon-133 and an aerosol of sulphur colloid tagged with technetium 99m, were performed while they were sitting. Before administration of histamine radioaerosol scintiscans were abnormal in five of six patients; after histamine challenge all were abnormal and central deposition was significantly greater in all of them. The decrease in aerosol penetration correlated with the percentage decrease in FEV1, indicating that the efficiency of aerodynamic filtration depends on the degree of airway narrowing. In six of the eight subjects the distribution of ventilation changed from predominantly basal to predominantly apical after histamine, which suggests the airways response was greater, at least initially, in the better ventilated regions. This indicates a close relationship between regional ventilation and the site of histamine deposition and has implications for the delivery of aerosolised agents in general.
The authors describe their technique of embolization, using detachable balloons to produce endovascular occlusion in three patients with multiple pulmonary arteriovenous fistulas and in one patient with a large peripheral aneurysm. The results were satisfactory. The clinical presentation and treatment course in each of the four patients are described and the role of this form of therapy is discussed. This method of endovascular occlusion is particularly appropriate for treating pulmonary arteriovenous fistulas and aneurysms because placement of the balloon is precise, permanent and localized and the flow of the balloon in the fistula or aneurysm can be directed.
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The effects of the beta-adrenoceptor blockers atenolol, metoprolol, pindolol, and propranolol on the ventilatory response to carbon dioxide rebreathing have been determined in a double-blind randomized manner. Eight healthy, male, nonsmoking subjects received cumulative doses of each drug over a 10-hr period. The effects of each drug on heart rate and carbon dioxide sensitivity were determined at intervals of 2 hr and were related to plasma concentrations of each drug. Maximum reduction of exercise heart rate was achieved with all four beta blockers and plasma concentrations were in the usual therapeutic range for these drugs. There was considerable intersubject and within-subject variability in ventilatory responsiveness to inhaled carbon dioxide, but we were not able to discern any alteration in central sensitivity to increasing carbon dioxide concentrations.
The synthesis of L-serine deaminase in Escherichia coli K-12 was induced after exposure of cells to a variety of DNA-damaging agents, including UV irradiation, nalidixic acid, and mitomycin C. Synthesis was also induced during growth at high temperature. A mutant constitutive for SOS functions showed an elevated level of L-serine deaminase activity. The response to DNA-damaging agents thus may be mediated via the SOS system.
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Diaphragmatic excursion was determined by percussion in 29 patients by two observers and then compared with measurements made from inspiration and expiration chest roentgenograms. The range of movement as determined by percussion was related to spirometric indices of ventilatory capacity. Our study showed wide interobserver variation in the clinical measurements and a poor correlation with diaphragmatic excursion measured roentgenographically. Although we were able to demonstrate a significant correlation between forced vital capacity (FVC) and clinically determined range of diaphragmatic movement, five patients had a reduced FVC despite the fact that the clinical determination of diaphragmatic movement was greater than 2 cm. Both observers missed paradoxical movement in the one patient in whom it was present. We conclude that percussion of th diaphragms for the purpose of estimating the range of movement is of limited clinical value and should no longer be recommended as part of the physical examination.
Two patients are described who developed progressive massive fibrosis (PMF) after exposure to coal dust for only four and seven years, respectively, in Belgian coal mines in the post-war period. It seems likely from consideration of epidemiological data that these men were exposed to massive concentrations of coal dust during their time in the mines. In one patient in a computerized tomography scan clearly showed the extent of the PMF and brought out the degree of calcification in the center of the masses. Radionuclide angiocardiographic evaluation showed depressed right ventricular function which is probably a result of pulmonary hypertension, and also showed marked distortion of the pulmonary vascular bed. It is believed that these are the first reported instances of CT scanning and radionuclide angiocardiography in this condition.
Two young men who had been exposed at work to epoxy resin powder containing trimellitic anhydride (TMA) presented with haemolytic anaemia and repeated haemoptyses. They did not return to work at the factory and the symptoms and the anaemia resolved spontaneously. Seven similar cases have lately been presented at meetings, so it seems that TMA, already known to cause respiratory syndromes such as asthma, can also lead to several extrapulmonary toxic effects, including haemoptyses and haemolytic anaemia. Studies on these patients' sera with TMA haptenised protein and cells pointed to an immunological mechanism.
The clinical, pathological, and neurochemical characteristics of a newly recognized inherited neurological disorder are reported. Lethargy and mental depression are early symptoms, followed by mild parkinsonism and progressive weight loss. Failure of automatic respiratory control develops and may result in sudden death. Advanced degeneration of the substantia nigra, cell loss and gliosis of the basal ganglia, and focal gliosis in the medulla are seen on pathological study. Degeneration of the nigrostriatal dopaminergic system is evidenced by low levels of tyrosine hydroxylase, dopamine, homovanillic acid, and L-dopa decarboxylase in postmortem brain samples. Taurine concentrations in fasting plasma and CSF are somewhat depressed; brain contents of taurine are within normal limits.
The computed tomography findings in alveolar disease are described in a patient with alveolar cell carcinoma. The recognition of an air bronchogram on CT scanning may be useful in establishing the alveolar nature of diffuse or focal lung disease.