| 1. |
- Gustafsson, D, et al.
(författare)
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Effects of calcium antagonists on myogenic and neurogenic control of resistance and capacitance vessels in cat skeletal muscle
- 1988
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Ingår i: Journal of Cardiovascular Pharmacology. - 0160-2446. ; 12:4, s. 22-413
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Tidskriftsartikel (refereegranskat)abstract
- The effects of five different calcium antagonists (diltiazem, felodipine, nifedipine, nimodipine, and verapamil) on cat skeletal muscle resistance and capacitance vessels were studied in a whole organ preparation. These calcium antagonists seemed to have the similar qualitative effects on these vascular functions. Calcium antagonists were found to be potent inhibitors of myogenic vascular reactivity (here defined as the maximal increase in flow resistance evoked by a sudden rise of transmural pressure). Basal vascular tone and vascular tone induced by low frequency stimulation of sympathetic nerves were both less sensitive to these drugs than vascular tone induced by myogenic vascular reactivity. Sympathetically mediated vascular tone at high stimulation frequencies seemed to be least sensitive. Further, resistance vessels were much more sensitive to these drugs than capacitance vessels. Finally, basal tone in the large bore arterioles were more sensitive than in the small bore arterioles, a surprising finding which was interpreted with the aid of computer simulations using a mathematical model of local vascular control in cat skeletal muscle. The model suggested that this difference could be due to a delicate interaction between myogenic vascular reactivity and metabolic vascular control. It is suggested that the inhibition of myogenic vascular reactivity is a factor contributing to the edema formation of calcium antagonists.
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| 2. |
- Lindberg, N.-O., et al.
(författare)
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Optimization of disintegration time and crushing strength of a tablet formulation
- 1985
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Ingår i: Drug Development and Industrial Pharmacy. - : Informa UK Limited. - 0363-9045 .- 1520-5762. ; 11:4, s. 931-944
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Tidskriftsartikel (refereegranskat)abstract
- In an experiment with a factorial design, the following aspects were scrutinized: the impact on disintegration time and crushing strength caused by the loss-on-drying of the granulation; the granule-size distribution; the lubricant concentration; the compression force; and the pre-compression. Both with regard to disintegration time and crushing strength, these factors were found to have a significant influence: the loss-on-drying of the granulation; the fraction less than 0.150 mm; the concentration of magnesium stearate; and the compression force. A reduction of the tablet disintegration time was obtained by means of an increase of the granulation moisture; by an increase of the fine fraction; or by a reduction of the lubricant concentration or the compression force. The tablet crushing strength was increased by reducing the deviation of the granulation loss-on-drying from approximately 4.6 %; by a reduction of the fine fraction; by decreasing the lubricant concentration; or by increasing the compression force. The fraction larger than 0.300 mm had no significant influence; nor did the pre-compression. Further, there were no significant interactions. By means of superimposing contour plots of disintegration time and crushing strength, a region was obtained where the requirements of disintegration time and crushing strength could be satisfied by controlling the processing variables.
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| 3. |
- Lindberg, N.-O., et al.
(författare)
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Optimizing the friability of a tablet formulation
- 1987
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Ingår i: Drug Development and Industrial Pharmacy. - : Informa UK Limited. - 0363-9045 .- 1520-5762. ; 13:6, s. 1063-1067
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Tidskriftsartikel (refereegranskat)abstract
- The impact on tablet friability caused by the loss-on-drying of the granulation, the granule-size distribution, the lubricant concentration, the compression force, and the pre-compression was scrutinized in a factorially designed experiment. A reduction of friability was obtained by reducing the deviation of the granulation loss-on-drying from approximately 4.6%; by decreasing the lubricant concentration; or by increasing the compression force.
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| 4. |
- Lindberg, N.-O., et al.
(författare)
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The granulation of a tablet formulation in a high-speed mixer, Diosna P 25
- 1985
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Ingår i: Drug Development and Industrial Pharmacy. - : Informa UK Limited. - 0363-9045 .- 1520-5762. ; 11:4, s. 917-930
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Tidskriftsartikel (refereegranskat)abstract
- The impeller speed, the loss-on-drying of starch, and the added amount of water significantly influenced these response variables: granule fractions of less than 0.150 mm and more than 2.00 mm; and granule median diameter. The influence of the drug concentration on the response variables was less important. All the response variables showed significant interactions. At a fixed impeller speed, the fine fraction was reduced when the loss-on-drying of starch increased, and when water was added in increasing amounts. The coarse fraction and granule median diameter increased along with an increasing moisture content in the starch. Increasing amounts of added water had the same effect. The response surface contours of a fraction less than 0.150 mm, and a fraction exceeding 2.00 mm, were plotted. So was the granule median diameter. Suitable levels for the processing variables involved in obtaining a granulation of the desired proportions - fine or coarse fraction - can be read from the contour plots. Heat was generated in the mixer during kneading, which caused some evaporation of water. The change in the rotation rate of the impeller during the addition of the granulating liquid can be used as an indication of the fraction percentages below 0.150 mm and above 2.00 mm, but not of the median diameter.
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| 5. |
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| 6. |
- Taxén, Lars, et al.
(författare)
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Discrete optimization of digital filters using Gaussian adaptation and quadratic function minimization
- 1987
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Ingår i: IEEE Transactions on Circuits and Systems. - : IEEE. - 0098-4094 .- 1558-1276. ; 34:10, s. 1238-1242
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a new strategy for discrete optimization of a function F(x) is presented. Let A be the region in the n-dimensional parameter space, where F{x) is less than some constant. First, A is located and characterized by a Gaussian search process, called Gaussian adaptation. This makes it possible to approximate the behavior of F(x) over A by a quadratic function Q(x). Q(x) is then optimized for the N best discrete solutions using a branch and bound technique. Finally, these points are evaluated for the best F(x) points. By various digital filter examples it win be demonstrated that the new method is more e capable of finding good solutions than methods presented so far
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