Biomedical subjects

D J Morton

Publications and source records attributed to D J Morton.

At least 109 records · Page 6Linked to original sources

PubMed1980

Interaction of aldolase with actin-containing filaments. Structural studies.

Electron micrographs of the paracrystals formed when fructose bisphosphate aldolase (EC 4.1.2.13) is added to actin-containing filaments were analysed by computer methods so that ultrastructural changes could be correlated with the various stoicheiometries of binding determined in the preceding paper [Walsh, Winzor, Clarke, Masters & Morton (1980) Biochem. J. 186, 89-98]. Paracrystals formed with aldolase and either F-actin or F-actin-tropomyosin have a single light transverse band every 38 nm, which is due to aldolase molecules cross-linking the filaments. In contrast, the paracrystals formed between aldolase and F-actin-tropomyosin-troponin filaments show two transverse bands every 38 nm: a major band, interpreted as aldolase binding to troponin, and a minor band, interpreted as aldolase cross-linking the filaments. The intensity of the minor band varies with Ca2+ concentration, being greatest when the Ca2+ concentration is low. A model for the different paracrystal structures which relates the various patterns and binding stoicheiometries to structural changes in the actin-containing filaments is proposed.

Actins↗

PubMed1980

Effect of electrical stimulation post mortem of bovine muscle on the binding of glycolytic enzymes. Functional and structural implications.

The extent of binding of glycolytic enzymes to the particulate fraction of homogenates was measured in bovine psoas muscle before and after electrical stimulation. In association with an accelerated glycolytic rate on stimulation, there was a significant increase in the binding of certain glycolytic enzymes, the most notable of which were phosphofructokinase, aldolase, glyceraldehyde 3-phosphate dehydrogenase and pyruvate kinase. From the known association of glycolytic enzymes with the I-band of muscle it is proposed that electrical stimulation of anaerobic muscle increases enzyme binding to actin filaments. Calculations of the extent of enzyme binding suggest that significant amounts of enzyme protein, particularly aldolase and glyceraldehyde 3-phosphate dehydrogenase, are associated with the actin filaments. The results also imply that kinetic parameters derived from considerations of the enzyme activity in the soluble state may not have direct application to the situation in the muscle fibre, particularly during accelerated glycolysis.

Animals↗

PubMed1979

Changes associated with glycolytic-enzyme binding in the equatorial X-ray-diffraction pattern of glycerinated rabbit psoas muscle.

The binding of fructose biphosphate aldolase to the thin filaments of glycerinated rabbit psoas muscle produces a significant change in its low-angle X-ray-diffraction pattern. The intensity of the (11) reflection relative to that of the (10) reflection increases by 26 +/- 3% (mean +/- S.E.M.), which is consistent with the increase in the mass of the thin filaments produced by enzyme binding. A similar effect is found with a mixture of aldolase and glyceraldehyde 3-phosphate dehydrogenase. The significance of the change in intensity is considered with reference to the interpretation of the equatorial patterns obtained from muscles in different physiological states. The magnitude of the increase in the relative intensity of the (11) reflection is lower than that observed between relaxed and contracting muscle and does not bring into question the interpretation linking changes in these patterns to cross-bridge movement. However, the effect due to enzyme binding may be important when making detailed interpretations of these changes. It may also be related to an unusual pattern sometimes observed in cardiac muscle.

Animals↗

PubMed1979

Night calls in a group practice.

Night calls attended in 1977 by four doctors in a group practice were analysed and divided into categories of urgency.Slightly over half the night calls were genuine emergencies, and only four per cent were totally unnecessary.

Aged↗

PubMed1978

The ward round.

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Consumer Behavior↗

PubMed1978

The use of a subscription agent's computer facilities in creating and maintaining a library's subscription profile.

A library's subscription profile should reflect the needs of library clientele, but creating such a profile can require extensive clerical work. It was found that a subscription agent's computerized facilities could be used to facilitate a program of this type by providing initial serial listings for use in a survey, by manipulating data obtained from such a survey, and by producing listings identifying resulting serial titles and costs according to requesting disciplines. The data base thus created is updated as subscriptions are added or deleted so that the profile remains current.

Computers↗

PubMed1977

An electron microscope study of the interaction between fructose diphosphate aldolase and actin-containing filaments.

The interaction of fructose diphosphate aldolase with F-actin, F-actin-tropomyosin, and F-actin-tropomyosin-troponin has been studied by using negative staining. In the absence of troponin, minor aggregates of aldolase and the F-actin filaments are formed. A well-ordered lattice structure is only formed in the case of the fully reconstituted filament when the filament-to-filament spacing is 18nm, and the cross-bridge spacing is 38.7 nm. Evidence is presented that the lattice is due to an interaction between troponin and aldolase. The minimum subunit structure of troponin, still capable of giving rise to a lattice, is the troponin-IT complex, which indicates that troponin-C is not involved in aldolase binding.

Actins↗

PubMed1977

Analysis of interlibrary requests by hospital libraries for photocopied journal articles.

A study of the 1975 borrowing requests made by all hospital libraries in central western Massachusetts showed that there were 4,368 requests for articles contained in 1,071 different periodical titles. The numbers of requests per title ranged from eighty-nine for one title to one for each of 123 titles. A graph of the data showed a geometric progression, and the Bradford constants for this dispersion averaged 1.28. The percentage of total requests related to the age of requested issues varied from 62.48% for items not over five years old and 78.15% for issues not over ten years, to 95.57% for materials not over thirty years old. Bradford constants averaged 2.13. Of the thirty most requested periodical titles, sixteen were published in foreign countries, as follows: England--ten; Netherlands--three; Australia--one; Canada--one; and Sweden--one. The study's significance included its total coverage of a relatively large and isolated region, its focus upon the records of requesting rather than lending libraries, and its analysis of interlibrary rather than in-house activities.

Interlibrary Loans↗

PubMed1976

Aldolase binding to actin-containing filaments. Formation of paracrystals.

Electron-microscopy observation show that when aldolase binds to F-actin or F-actin-tropomyosin, highly ordered paracrystalline structures are formed consisting of tightly packed filament bundles cross-banded at 36 nm intervals. Morphologically different paracrystalline arrays are formed between aldolase and F-actin-tropomyosin-troponin. The filament bundles are far more extensive and are characterized by a prominent cross-striation at 38nm intervals. It is suggested that this reflects an interaction between troponin and aldolase.

Actins↗

PubMed1974