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At least 217 records · Page 12Linked to original sources
PubMed1993

The application of the theoretical model WHO/FDI planning system to an industrialised country: France.

The results of the application of the WHO/FDI planning system to a specific situation in an industrialised country provide valid arguments in favour of its use. It is shown to be an aid to planners when estimating oral health personnel requirements and emphasises the necessity of obtaining basic information on the oral health status and demand for treatment in industrialised countries. The strength of the system lies in the fact that it enables the user to forecast requirements, by age cohort and by type of care, while at the same time including socio-economic variables which have a major influence in industrialised countries with moderate caries levels. This flexibility of use enables the system to be adapted, if necessary, or even improved, according to the constraints which may result from a specific situation analysis.

Adolescent↗
PubMed1996

Theoretical modelling of the release rate of low-density lipoproteins and their breakdown products at arterial stenoses.

Arterial stenoses and luminal-surface irregularities at anastomoses cause blood-flow disturbances with slow recirculation. The authors created a computer simulation to study the rates of the release into blood of atherogenic substances such as low-density lipoproteins and their breakdown products from within the arterial walls at stenoses. Finite-difference methods were used to solve the Navier-Stokes equations (in the form of stream function and vorticity function) and the steady-state mass transfer equation for bell-shaped stenoses with two different degrees of constriction. This simulation indicated that the efflux rates of lipids and their breakdown products from the vessel walls were suppressed in the region of disturbed flow, with slow circulation distal to stenoses. The lowest efflux rate was found at the point of flow separation, and this rate was much lower than rates in regions of undisturbed flow. Therefore, this mathematical model predicts that locally disturbed blood flow at arterial stenoses and arterial anastomoses is responsible for two distinct phenomena: first, it provides favourable conditions for lipid infiltration into vessel walls; and, second, it impairs the release into the blood of atherogenic substances accumulated in the vessel wall. Such mass transfer abnormalities may account for atherogenesis and the late failures of arterial reconstructions at these sites.

Animals↗
PubMed1997

A theoretical model of some spatial and temporal aspects of the mitochondrion creatine kinase myofibril system in muscle.

We describe a model of mitochondrial regulation in vivo which takes account of spatial diffusion of high-energy (ATP and phosphocreatine) and low-energy metabolites (ADP and creatine), their interconversion by creatine kinase (which is not assumed to be at equilibrium), and possible functional 'coupling' between the components of creatine kinase associated with the mitochondrial adenine nucleotide translocase and the myofibrillar ATPase. At high creatine kinase activity, the degree of functional coupling at either the mitochondrial or ATPase end has little effect on relationships between oxidative ATP synthesis rate and spatially-averaged metabolite concentrations. However, lowering the creatine kinase activity raises the mean steady state ADP and creatine concentrations, to a degree which depends on the degree of coupling. At high creatine kinase activity, the fraction of flow carried by ATP is small. Lowering the creatine kinase activity raises this fraction, especially when there is little functional coupling. All metabolites show small spatial gradients, more so at low cytosolic creatine kinase activity, and unless there is near-complete coupling, so does net creatine kinase flux. During workjump transitions, spatial-average responses exhibit near-exponential kinetics as expected, while concentration changes start at the ATPase end and propagate towards the mitochondrion, damped in time and space.

Animals↗