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Biomedical subjects

L Reid

Publications and source records attributed to L Reid.

At least 127 records · Page 7Linked to original sources
PubMed1978

Bronchial atresia: a recognizable entity in the pediatric age group.

Bronchial atresia, a congenital lesion that develops after the 16th wk of fetal life, may be more common than previously believed, and this probably explains some cases of so-called congenital lobar emphysema. It may produce symptoms of pulmonary infection, wheezing, and respiratory distress severe enough to justify elective resection of that part of the lung distal to the atresia. The roentgenographic features that make this a recognizable entity are the following: (1) There is localized hyperinflation of lung in a segmental or lobar distribution, with a circular or oval parahilar radiodensity. Bronchography will demonstrate that there is no filling of the bronchus supplying this part of the lung. (2) The occasional neonate with this condition may present with an intrathoracic mass suggesting retained fetal lung fluid in lobar distribution. Bronchography will demonstrate that there is no filling of the bronchus to that part of the lung. (3) A plug of desquamated tissue and mucus in the cyst-like bronchus just distal to the point of atresia appears to be an unvarying component of the syndrome. It most commonly presents as a round or oval density, but in some cases it may be shaped like a rod or tree and rarely contains an air-fluid level.

Adolescent↗
PubMed1978

A morphometric study of regional variation in lung structure in infants with pulmonary hypertension and congenital cardiac defect. A justification of lung biopsy.

The structure of the pulmonary circulation throughout the lung has been analysed by morphometric techniques in 4 infants dying with ventricular septal defect and pulmonary hypertension. Failure of the intra-acinar pulmonary circulation to develop normally is shown by a reduction in arterial size and number, and an increase in muscularity is judged by the degree of medial hypertrophy and by extension of muscle further along the arterial pathway than is normal. For these features, one section of lung tissue, 1 cm square, proved to be representative of the entire pulmonary vascular bed, and also gave satisfactory assessment of lung growth and development. Lung biopsy can help in the clinical management of children with congenital cardiac defects and pulmonary hypertension if, in selecting tissue at biopsy, allowance is made for any regional differences in pulmonary blood flow.

Anthropometry↗
PubMed1978

Pus, deoxyribonucleic acid, and sputum viscosity.

On 100 sputum specimens selected from patients suffering from chronic bronchitis, bronchiectasis, asthma, and cystic fibrosis total deoxyribonucleic acid (DNA) content has been related to macroscopic type, to total dry weight yield, and to the apparent viscosity of the secretion at 1350 s-1: since DNA may be present, either as fibres or within cells, in one-third of the specimens the contribution of each form to the apparent viscosity was assessed. The effect on sputum viscosity of the addition of DNA in vitro has also been studied. Whereas between mucoid, mucopurulent, and purulent macroscopic types a significant difference in total DNA and dry weight yield has been found, viscosity was not significantly correlated with purulence. Similarly, the concentration of either cells or fibres correlated significantly with total DNA but not with viscosity. The in vitro addition of DNA to sputum caused a significant increase in its viscosity, and reasons for the differences between the iv vivo and in vitro effect are discussed. Certain constituents of purulent sputum tend to increase viscosity and others to reduce it, and the influence of these varies in the several diseases studied.

Adolescent↗
PubMed1978

Growth of pulmonary circulation in normal pig--structural analysis and cardiopulmonary function.

Morphometric analysis of the postnatal development of the pig lung, with emphasis on alveoli and vessels, shows features of growth similar to man, but occurring at a much faster rate in the pig, which telescopes in the first 3 mo the changes seen in human childhood and adolescence. During the first weeks, arteries (birth to 2 wk) and alveoli (1--12 wk) increase in number, whereas increase in size continues until adulthood. Wall thickness decreases soon after birth in arteries 15--200 micrometer, and by 8 wk in those 200-1,000 micrometer. At this age the adult left ventricular predominance in weight is already present. Throughout growth the venous wall thickness does not change. Cardiopulmonary function studies in pigs, from 2 to 16 wk, show that, during the period of rapid postnatal lung growth, there is no change in tidal volume, dynamic compliance, and thoracic gas volume as related to body weight; right ventricular and pulmonary arterial pressures also remain unchanged, whereas pulmonary vascular resistance decreases during the 1st mo.

Animals↗
PubMed1978

Chemical markers of mucous and serum glycoproteins and their relation to viscosity in mucoid and purulent sputum from various hypersecretory diseases.

Mucus and serum are always present in sputum. The concentrations of their markers were measured in mucoid and purulent sputum from patients with chronic bronchitis, asthma, cystic fibrosis, or bronchiectasis. Differences in the concentrations of both mucous and serum glycoproteins were greater among different macroscopic types of sputum than among diseases for the same macroscopic type. Comparison between diseases showed that sputum from patients with asthma had the widest variation in concentrations of markers of mucous glycoprotein and dry macromolecular weight. When the asthma group was further analyzed, it became apparent that patients with extrinsic asthma without chronic bronchitis represented a homogeneous group, whereas those with intrinsic asthma, with or without chronic bronchitis, were responsible for the wide variation. The concentrations of markers of mucous and serum glycoproteins in a sputum sample were correlated with the apparent viscosity of the sputum to establish the relative contribution of the glycoproteins to the viscosity of sputum. In mucoid sputum, the mucous glycoprotein was most important in determining the viscosity, whereas when in infected sputum, both mucous and serum components contributed to the viscosity.

Asthma↗
PubMed1978

The effect of continued hypoxia on rat pulmonary arterial circulation. An ultrastructural study.

Hypoxia is known to cause pulmonary hypertension with an increase in arterial muscle-both hypertrophy of the medial coat of the normally muscular arteries and development of new muscle more peripherally than is normal--and a decrease in the number of small arteries. The present study descirbes the ultrastructural features of these changes. Pulmonary arteries less than 100 microgram. in diameter after distension and including alveolar capillaries and the muscular arter at the hilum were examined after exposure to 380 torr for between 1 and 52 days. The earliest change, detected from day 2, is the appearance of new muscle in the nonmuscular regions of artery. The position of the new muscle internal to the single elastic lamina and immediately subjacent to endothelium distinguished it from normal muscle. Ultrastructural examination shows not an "extension" of muscle along a pathway, but differentiation to form new muscle, by preexisting cells--by the pericyte in the nonmuscular arteries and by the intermediate cell in the partially muscular. The veins are spared. Endothelial cells also change significantly from day 3. In the normally nonmuscular regions of artery and in the alveolar capillaries, they are thickened. In the nonmuscular regions of artery, although the endothelial cells appear edematous, the number of Weibel-Palade bodies is increased and new muscle appears subjacent. Elsewhere the Weibel-Palade bodies show normal distribution. The extreme narrowing of the lumen caused by thickened endothelial cells and by encroachment of new muscle as well as the finding of capillaries that are no longer patent doubtless explain the reduction in small peripheral areteries.

Animals↗
PubMed1978

Pulmonary arteries of the normal rat: the thick walled oblique muscle segment.

The structure and certain metrical features of the pulmonary arterial tree in the normal rat have been studied in detail by both light and electron microscopy after its distension by injection. In the parts of the tree where the muscle wall is complete a segment with oblique muscle has been identified. The wall of this segment is thick, and is composed largely of obliquely orientated, closely packed smooth muscle cells with little intervening connective tissue, while it lacks a complete external elastic lamina. Both the axial pathway and its side branches have such oblique segments. Proximal and distal to an oblique segment there are transitional regions where obliquely arranged muscle fibres spiral external to the circularly arranged fibres usually described in muscular arteries. The existence of thick walled oblique muscle segments in the pulmonary arterial tree of the normal rat is important since this animal is frequently used in experimental studies, and the thick segments could be taken as evidence of induced hypertrophy.

Animals↗
PubMed1978

Normal structure and dimensions of the pulmonary arteries in the rat.

The normal structure and pattern of branching of the pulmonary arteries of the rat have been described and quantified, using precise morphometric techniques, after injection of the pulmonary arteries with a radio-opaque medium. Rats of the same strain from three different sources have been compared, and similarities between rat and man have been assessed. In rat, as in man, the pulmonary artery accompanies the airway and branches with it and, in addition, there are extra arterial branches. Most arteries within the rat lung are muscular and have no more than two central elastic laminae. The percentage wall thickness of the muscular arteries is between 1 and 3%, similar to that found in adult human lungs. At the periphery of the arterial tree there is a mixed population of muscular, partially muscular and non-muscular arteries. The distribution by size is similar in man and rat, but there are few wholly muscular arteries within the acinar region in the rat. The similarity of the features of the pulmonary arteries of rat and man makes the rat a suitable experimental animal for study of changes in pulmonary hypertension. However, any change must be interpreted in relation to arterial structure in normal rat lungs from the same source, since some significant differences have been found between rats from different sources in respect of wall thickness and number of vessels.

Animals↗
PubMed1978

The effect of isoprenaline and pilocarpine on mitotic index and goblet cell number in rat respiratory epithelium.

The effect of both isoprenaline (IPN) and pilocarpine (PCP) on mitotic activity and goblet cell number has been studied at 5 levels of the bronchial tree in male and female animals. While both drugs increased mitotic index and goblet cell number at most of the airway levels studied, differences in their effect were detected. After both drugs, nuclei in division were more often superficial within the epithelium than basal but IPN caused a greater increase in mitotic index than PCP. IPN increased goblet cell number at all levels, PCP only in the trachea and larger intrapulmonary airways. The types of goblet cell increased by IPN were particularly those containing acid glycoprotein, whereas PCP increased all types of goblet cell, that is, both those containing neutral and acid glycoprotein. After the drugs, the concentration of cells per unit length of airway epithelium was higher than normal. This is the first study demonstrating the effect of these two drugs on both goblet cell number and cell division. While the two drugs differ in their pharmacological action, the result of their stimulation of airway epithelium is similar. The way in which each effect is produced is discussed.

Animals↗
PubMed1977

The separation and characterization of bronchial glycoproteins by density-gradient methods.

1. Sputum samples from a total of 18 asthmatic and chronic bronchitic patients were examined by analytical density-gradient ultracentrifugation. CsBr was used as the dispersal agent and dense electrolyte. 2. The patterns show two main groups of components, banding at about 1.3g/ml and 1.5g/ml; in addition, a few samples showed a further zone at approx. 1.65g/ml. These components were identified as protein, secretory glycoprotein and DNA respectively. The glycoprotein zone was frequently hypersharp, and usually contained two or more partially resolved bands; it was always well resolved from the protein. 3. The glycoprotein components were isolated from nine representative sputum samples by density-gradient ultracentrifugation on a preparative scale. Analytical density-gradient ultracentrifugation was used to monitor the efficiency of the separations. 4. Some sputum samples separated cleanly under these conditions, the glycoprotein being essentially devoid of free protein; in others, separation was apparently incomplete, although computer simulation indicated that the conditions were adequate to ensure separation. Further density-gradient separations in CsCl were necessary with several samples before satisfactory products were obtained; mixtures of CsCl with guanidinium chloride were no more effective than CsCl alone. The reluctance to separate indicates a very strong, but non-covalent, interaction between protein and glycoprotein, probably associated with the gelatinous character of the secretion. 5. The purified glycoprotein components were characterized analytically and physicochemically. They contained N-acetylgalactosamine, N-acetylglucosamine, galactose, fucose and N-acetylneuraminic acid, and had an amino acid composition in which serine, threonine and proline predominated; however, aspartic acid, glutamic acid and cystine were also appreciable. The glycoproteins were of very high molecular weight, and usually showed more than one component in sedimentation velocity; their distribution in a density gradient indicated a substantial, but largely monotonic, density heterogeneity. 6. Thiol reduction decreased the molecular weight very substantially, but the products were relatively more homogeneous than the native materials. The amino acid composition was changed significantly and a small and variable proportion of protein or peptide was liberated. It is concluded that the native materials are disulphide-linked aggregates, probably through a cross-linking peptide, in confirmation of earlier studies.

Amino Acids↗
PubMed1977

Hearing aid gain-setting performance of experienced users.

This study explores the ability of 30 experienced hearing aid users to reliably reset the gain of their hearing aids in a clinical sound field. The level of the sound-field stimulus was derived from an aided most comfortable level (MCL), which reflected a "real-life" aided gain setting. The results indicated that these subjects were able to perform all tasks with a high degree of reliability, as measured by sound field speech reception thresholds (SRT'S) AND Brüel and Kjaer acoustic analysis. Average aided operational levels for SRT and MCL were also obtained for this group.

Acoustic Stimulation↗
PubMed1977

Pulmonary hypoplasia in babies with severe rhesus isoimmunisation: a quantitative study.

Analysis of lung weights of 96 infants dying with rhesus isoimmunisation has shown that the lung is considerably retarded in its growth. Detailed analysis of the lungs of six babies after pulmonary artery injection showed in all a reduction in airway number and thus acinar and artery number, suggesting arrest in growth before the 16th week of gestation. The alveoli were also of either abnormal number, size or maturity, suggesting a continuing effect in later foetal life. Total lung volume varied from the normal value in one case to one-quarter normal in the smallest lung.

Angiography↗