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  • 1
    ISSN: 1432-0428
    Keywords: Keywords MODY-2 ; glucokinase ; glucose threshold ; insulin secretion ; beta-cell ; mathematical model.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Aims/hypothesis. Mutations of the glucokinase gene cause hyperglycaemia or hypoglycaemia. A quantitative understanding of these defects of glucose homeostasis linked to the glucokinase gene was lacking. Therefore a database of kinetic variables of wild-type and 20 missense mutants of glucokinase was developed and used in mathematical modelling to predict the thresholds for glucose-stimulated insulin release. Methods. Recombinant human glucokinase was generated in E. coli. The kcat, glucose S0.5, ATP Km, and Hill number of glucokinase were determined. Inhibition by Stearoyl CoA and glucokinase regulatory protein and thermal stability were assayed for all mutants kinetically similar to wild-type glucokinase. A mathematical model predicting the threshold for glucose-stimulated insulin release was constructed. This model is based on the two substrate kinetics of glucokinase and the kinetic variables of the database. It is assumed that both glucokinase gene alleles are equally expressed in beta-cells and that induction of glucokinase occurs as a function of basal blood glucose. Results. Large changes, varying greatly between mutants were found in nearly all variables. Glucokinase flux at threshold for glucose-stimulated insulin release was about 25 % of total phosphorylating potential in the normal beta-cell and this was used to predict thresholds for the mutant heterozygotes. Clinical data for maturity onset diabetes of the young type linked to the glucokinase gene and familial hyperinsulinaemic hypoglycaemia linked to the glucokinase gene and the glucokinase kinetic data of this study were used to test the model. The model predicts fasting blood glucose between 3 and 7 mmol/l in these cases. Conclusion/interpretation. A kinetics database of wild-type and 20 mutants of glucokinase was developed. Many kinetic differences were found for the mutants. The mathematical model to calculate the threshold for glucose-stimulated insulin release predicts fasting blood glucose between 3 and 7 mmol/l in subjects with glucokinase gene mutations. [Diabetologia 42: 1175–1186]
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 42 (1977), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence on water loss rates of beef muscle of varying the rate of air flow past the cooking muscle, the orientation of the muscle fibers relative to the direction of air flow, and the postmortem treatment of the muscle prior to cooking in a controlled environment oven was evaluated. Variation in flow rate did not change the basic mechanism of water transport (i.e., did not change qualitative features of the emission curve) but did increase the water emission rate in the constant rate period and the first falling rate period. Perpendicular fiber orientation with respect to air flow direction gave a higher rate of water loss in the early staees of cookina. Muscles that entered rieor in a restrained position gave higher water loss rates than those that entered rigor in an unrestrained position. Scanning electron microscopy showed looser structure of the myofibrils in the restrained muscle which could account for the higher water loss rates.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 42 (1977), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental data are presented for water emission rates and temperature profiles of beef muscle that is heated in an especially constructed controlled environment oven in which air temperature, flow rate and humidity are continuously monitored and controlled at all times. Moisture loss rates and temperature rise in bovine semitendinosus muscle were measured for oven temperatures between 121°C and 204° C and for an air flow rate of 13.7 m3/hr in which fiber direction was parallel to the direction of the air flow. A qualitative model of heat and mass transfer is deduced that illustrates the interaction of heat and mass transfer during dry air roasting. The transport mechanisms known to be operative in the drying of rigid, nonproteinous porous media provide the basis for understanding the water emission behavior of cooking muscle.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 45 (1980), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Five emulsifier combinations as well as hydrogenated vegetable shortening and unemulsified oil controls were tested in a research cake formula. Water loss and temperatures were monitored continuously during baking in a specially constructed environmental oven. Both the water loss rate and rate of temperature increase were depressed in the temperature ranges associated with starch gelatinization. The degree of depression was related to the emulsification system. Granule swelling as observed by scanning electron microscopy of the crumb was not greatly different, but the characteristics of the inter-granule matrix appeared to be related to the concentration of emulsifier.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 43 (1978), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The mechanisms of water loss and their relation to muscle shortening were investigated by dry cooking in a controlled environment oven. Air was pumped vertically upward in the oven at a rate of 13.7 m3/hr. Cylindrical muscle samples were cooked at 121°C, 149°C and 177°C. The axes of these samples were in vertical, 45° and horizontal directions with respect to the oven. The muscle fibers were parallel to the axes of these samples. It is observed that total weight loss is almost independent of sample orientation, implying that the draining of fluid by gravity (a mechanism which is believed to be closely related to sample orientation) is not an important mechanism of mass transfer. The main mechanism is possibly fiber shrinkage which squeezes fluid out during cooking. Linear relationships between remaining water content and sample length were observed both before and after protein denaturation. The slopes of these two linear relations are different, suggesting that the way fluid is squeezed out is different before and after protein denaturation. Also, these slopes are almost independent of oven temperature in the 121-177°C range, suggesting that the remaining moisture content depends primarily on the shortening during cooking of a sample and only weakly on the oven temperature and initial condition (i.e., frozen or frozen-thawed) of the sample.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food processing and preservation 3 (1980), S. 0 
    ISSN: 1745-4549
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Rates of water loss and temperature profiles and concentric regional moisture contents were determined for 100 g cylindrical potato tuber samples heated at temperatures of 99°C, 143°C and 177°C. Heats of gelatinization for potato tuber were determined by differential scanning calorimetry. Structural changes were observed at various cooking times and dryness levels of heated potato tuber. It was found that the rate of moisture loss is controlled by the gelatinization of the starch which seems to occur almost simultaneously throughout the sample for this sample size. Initial water loss was also controlled by the rate at which the temperature rose to 100°C until the falling rate period began. From SEM measurement of the dry surface crust which is formed early during the heating process, it was concluded that the crust is the main thermal resistance to cooking.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 52 (1987), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model of microwave thawing of homogeneous food products is developed and solved numerically using the Modified Isotherm Migration Method. The model is used to predict thawing time and temperature profiles for microwave thawed meat cylinders at three frequencies (2450 MHz, 915 MHz, 300 MHz) and different power levels. Model and experimental results for thawing a lean beef cylinder heated at low microwave power using 2450 MHz frequency compare well. The advantage of using 915 or 300 MHz power over 2450 MHz power is shown by calculations. The results show that microwaves significantly accelerate the thawing rate. The mathematical model is explored as a tool for designing optimal microwave/convective heating protocols for rapidly thawing foods in desired temperature ranges.
    Type of Medium: Electronic Resource
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  • 8
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    Unknown
    Urbana, etc. : Periodicals Archive Online (PAO)
    American Journal of Psychology. 49 (1937) 315 
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  • 9
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 271 (1978), S. 689-690 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] PHYSICISTS weaned on the nearly-free-electron theory of solids find it satisfying, if at first surprising, that the properties of most liquid metals can be treated within this approximation. As long as the scattering of the conduction electrons by the non-crystalline arrangement of atoms is weak, ...
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 88 (1985), S. 281-284 
    ISSN: 1573-5036
    Keywords: Glomus spp. ; Liming ; Liquidam bar styraciflua ; Sorghum sudanense ; Glomus diaphanum pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Potential growth stimulation of two hosts by acid-tolerantAcaulospora laevis was tested in a soil adjusted to 5 pH levels from 5.0 to 7.7. By wet-sieving methods, the field-source inoculum was essentially a pure culture ofA. laevis spores. Upon harvest of sweetgum a completely different spore-type was found in large quantities;A. laevis spores were relatively few to non-existent. The results dramatically underscore the need for caution against relying solely on pre-trial identifications of inoculum spores or presuming that apparently single-species cultures/inoculum will remain pure throughout an experiment.
    Type of Medium: Electronic Resource
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