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Biomedical subjects

J J Reid

Publications and source records attributed to J J Reid.

70 records · Page 4Linked to original sources
PubMed1978

Intracellular transport and packaging of prolactin: a quantitative electron microscope autoradiographic study of mammotrophs dissociated from rat pituitaries.

Dispersed pituitary cells prepared from estrogen-treated female rats were subjected to pulse labeling with [3H]leucine (5 min) followed by a chase incubation (up to 3 h) in order to study intracellular transport of PRL in mammotrophs. Sites of synthesis, rates of transport, and sites of packaging and storage of PRL were determined by quantitative electron microscopic autoradiography. Results of grain counts show that label is initially (end of pulse) distributed randomly over the rough endoplasmic reticulum (ER), but rapidly (5--15 min of chase) moves to the stacked Golgi cisternae where concentration into secretion granules takes place. The label moves successively from small (Type I) immature granules (15--55 min of chase) to large (Types II and III) polymorphic granules (55--115 min) in the Golgi region, to rounded or ovoid mature (Type IV) granules (55--185 min) usually found in the peripheral cytoplasm, indicating that these types of granules represent successive stages in granule concentration and assembly. Analysis of the relative grain density (percentage of total grains/percentage of total area) confirmed that there was progressive concentration (up to 20--150 times) along the transport route with the concentration lowest in the ER, higher in the Golgi, and highest in immature and mature secretion granules. These data indicate that synthesis of PRL occurs randomly in the ER, transport to the Golgi occurs rapidly (within 5--10 min), and is completed rapidly (90% within 15--20 min), and concentration into granules and aggregation of small granules into larger forms also occurs rapidly (by 15--20 min), but goes on over a prolonged period of time (up to 3 h). Use of dispersed cells has allowed a more precise determination of the location and kinetics of steps in the intracellular processing of PRL than has been possible previously using other systems.

Animals↗
PubMed1976

Alterations of the glomerular epithelium in acute aminonucleoside nephrosis. Evidence for formation of occluding junctions and epithelial cell detachment.

The visceral glomerular epithelium of rats made nephrotic by daily injections of puromycin aminonucleoside was examined from the time of onset of proteinuria (day 6) to the time when many animals die (day 15) in order to establish the chronology of the pathologic alterations which occur during the course of the disease. In addition, the structure of the residual epithelial slits was examined using special fixatives and freeze-fracture. Changes seen early in the disease (7 to 9 days) are: (1) a reduction in the number of foot processes and filtration slits; (2) occurrence of occluding junctions in many of the residual slits coupled with displacement of the slit diaphragms; (3) thinning of the dense central portion of the basement membrane (lamina densa) with a corresponding widening of the space (lamina rara externa) between it and the epithelium; (4) heightened epithelial pinocytosis with increased numbers of protein absorption droplets or lysosomes. In freeze-fracture preparations the occluding junctions were seen to be limited in extent and made up of only a few strands, indicating they are incomplete and represent occluding maculae or fasciae rather than zonulae. Later on in the disease (10 to 15 days) no further changes in the number or arrangement of slits is evident, but other alterations occur: (1) denuded regions of basement membrane are seen where there is initially partial and eventually complete detachment of the epithelium from the basement membrane; (2) increasing numbers of large vacuoles or phagosomes and decreasing numbers of fully condensed lysosomes are present; and (3) basement membrane-like material is seen in the spaces between the partially detached epithelium and basement membrane. The new findings in this study are: (1) the clarification of early (reversible) versus late (probably irreversible) changes in the glomerular epithelium in a acute aminonucleoside nephrosis; (2) delineation of the structure of the residual epithelial slits; (3) the description of progressive loosening of the attachment between the epithelium and the basement membrane leading to focal or complete epithelial cell detachment; (4) the presentation of evidence indicating that exhaustion of the lysosomal system of the glomerular epithelium (in protein absorption and concentration) occurs late in the disease. The available evidence is summarized and indicates that the glomerular basement membrane, the main glomerular filter, is defective in aminonucleoside nephrosis and allows increased protein leakage. However, it seems likely that the main site of action of aminonucleoside is on the epithelium leading to the production of defective basement membrane.

Animals↗
PubMed1975

Health service planning in a British new town.

The initial postwar development of new towns in Britain took place at a time when the present British National Health Service was in its infancy, and few attempts were made to integrate health service planning into the overall planning process. The more recent new towns have been the object of better social planning and, at the same time, the National Health Service has been substantially unified, at first functionally and, in 1974, administratively. In consequence, attempts have been made to use the opportunities which such towns present for planning health services in a comprehensive and integrated manner. The evolution of a planning and implementation structure for health services in Milton Keynes, a new town with a target population of 250,000, is described, together with some of the implications for the administratively unified National Health Service which came into being in 1974.

City Planning↗