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Biomedical subjects

A S Craig

Publications and source records attributed to A S Craig.

43 records · Page 3Linked to original sources
PubMed1971

Plants under Climatic Stress: II. Low Temperature, High Light Effects on Chloroplast Ultrastructure.

Mesophyll chloroplasts of the C(4)-pathway grasses Sorghum and Paspalum and of the C(3)-pathway legume soybean undergo ultrastructural changes under moderate light intensities (170 w.m(-2), 400-700 nanometers) at a tme when photosynthesis is much reduced by low temperature (10 C). The pattern of ultrastructural change was similar in these species, despite some differences in the initial sites of low temperature action on photosynthesis and differences in their mechanisms of CO(2) fixation. Starch grains in the chloroplasts rapidly reduce in size when chilling stress is applied. At or before the time starch grains completely disappear the membranes of the individual stromal thylakoids close together, reducing the intraspace between them while the chloroplast as a whole begins to swell. Extensive granal stacking appears to hold the thylakoids in position for some time, causing initial swelling to occur in the zone of the peripheral reticulum, when present. At more advanced stages of swelling the thylakoid system unravels while the thylakoid intraspaces dilate markedly. Initial thylakoid intraspace contraction is tentatively ascribed to an increase in the transmembrane hydrogen ion gradient causing movement of cations and undissociated organic acids from the thylakoid intraspace to the stroma. Chloroplast swelling may be caused by a hold-up of some osmotically active photosynthetic product in the chloroplast stroma. After granal unraveling and redilation of the thylakoid intraspaces, chloroplasts appear similar to those isolated in low salt hypotonic media. At the initial stages of stress-induced ultrastructural change, a marked gradient in degree of chloroplast swelling is seen within and between cells, being most pronounced near the surface of the leaf directly exposed to light.

Journal Article↗
PubMedDate not supplied

Preservation of corneal collagen fibril structure using low-temperature procedures for electron microscopy.

Low-temperature dehydration and embedding techniques have been used to preserve the transverse structure of corneal collagen fibrils for study using electron microscopy. The diameters of the fibrils, which were found to be about 45% larger than those determined previously for specimens prepared for electron microscopy using conventional dehydration and embedding, lie close to those deduced from low-angle X-ray diffraction patterns from untreated hydrated specimens of cornea.

Animals↗
PubMedDate not supplied

Hospital responses to a data-driven statewide quality improvement project.

BACKGROUND: The overall success of any continuous quality improvement (CQI) project lies in the ability to measure changes resulting from the project and to show that changes have resulted n improved care. METHOD: A software tool was developed to categorize hospital responses and activities implemented by hospitals as a result of the Cooperative Cardiovascular Project CCP). Information was captured regarding the hospital's acceptance of data and the educational/interventional strategies implemented. Hospital size, number of acute myocardial infarction patients treated, indicator performances, and type of presentation given (on-site versus regional visit) was entered to allow analysis of factors affecting the response. RESULT: sixty-one of 107 hospitals responded to the peer review organization. Of those, 49% planned further educational activities and 75% planned to implement some form of CQI activity. Comparison of responses in relation to the type of presentation received suggested that on-site presentations are associated with higher response rates and more intense quality improvement efforts. This also could be attributed to other factors such as hospital size, teaching environment, or number of acute myocardial infarction patients treated. CONCLUSION: The system developed allowed us to collate hospital improvement efforts as a result of CCP. The system is limited in its ability to identify those activities taking place before CCP. Further development and refinement of the tool is warranted to document quality improvement efforts and determine best strategies for peer review organization intervention.

Abstracting and Indexing↗