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Biomedical subjects

W Beier

Publications and source records attributed to W Beier.

At least 55 records · Page 3Linked to original sources
PubMedDate not supplied

Sustained release properties of the once daily theophylline capsule BY912 as compared with Theo-24 capsules.

In a multiple dose cross-over experiment in 12 healthy male adults the bioavailability and sustained release characteristics of new once daily BY912 400 mg theophylline capsules (= B, Byk Gulden Research Laboratories, FRG) were studied using Theo-24 capsules (= T, Searle & Co., USA) as reference. Both products were given once daily for a period of 7 days as an 800 mg theophylline dose at 8 am, half an hour after a standardized breakfast. Theophylline concentrations in plasma were measured on days 1, 6, and 7 using high-performance liquid chromatography. Significantly better sustained release characteristics, resulting in longer plateau time (t75%, 11.6 vs 9.2 h on day 6 and 13.1 vs 8.8 h on day 7) and smaller per cent peak-trough fluctuation in the steady state (per cent PTF, 80 vs 103 per cent on day 6 and 66 vs 100 per cent on day 7), were found for B in comparison with T. The extent of absorption on both days, however, was smaller for B compared with T (relative bioavailability 84 per cent and 81 per cent, respectively). In conclusion, the absorption of theophylline from B resulted in a more extended shape of the plateau phase, indicating better sustained release characteristics. The extent of absorption, however, over the dosing intervals was more complete with T.

Adult↗
PubMedDate not supplied

Alterations of pulmonary vascular resistance and pulmonary cyclic nucleotide metabolism in the hypoxic pig.

Hypoxia leads to an elevation of the pulmonary vascular resistance (pvR) in pigs. This alteration of the hemodynamic was accompanied by a slight increase of intraparenchymatous concentrations of cyclic GMP (cGMP), while cycle AMP (cAMP) levels were not different from values, measured during normoxia. beta-adrenergic agents are potent inhibitors of the hypoxia induced vasoconstriction. This effect was associated with an increase of intraparenchymatous cAMP-concentrations and a decrease of cGMP-levels. The regression analysis between pvR versus the ratio cGMP/cAMP revealed a significant linear correlation. These data may indicate, that cAMP and cGMP are involved in hypoxia induced vasoconstriction and its pharmacological inhibition.

Animals↗
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Measuring human aging using a two-compartmental mathematical model and the vitality concept.

We calculated a theoretical vitality function as a reference curve, based on experimental results from 226 healthy individuals. This can be used to assess biological aging rates of geographically separate human populations. Only six parameters were used to assess vitality. Each parameter is associated with one of the two physiological compartments. We assume that one compartment keeps the system stable and the other maintains system fidelity. The results permit us to compare vitality curves within populations as well as to determine the age at which maximum vitality appears in each population. The differences between biological and chronological ages in each population and possible etiological interpretations are discussed. This mathematical model can be useful as a method to measure differences in aging rates and effects of aging in several human populations.

Journal Article↗
PubMedDate not supplied

[Kinematics of biological aging. II].

Using privation instead of physical time, a function of the theoretical vitality is found which depends on the parameter x. It is given by the quotient of growth-rate to age-rate. Consequences which could result from a possible continuity of such a relation are discussed.

Aging↗
PubMedDate not supplied

Assessment of the age of atherosclerosis risk in population studies using a two factorial mathematical model.

The risk of atherosclerosis was assessed using a mathematical model of competition between LDL and HDL on 365 randomly selected persons. The results speak for the fact that the risk falls between the ages of 30 and 40 years for males, and 40 and 50 years for females. We are of the opinion that our procedure may be valid for sex comparison studies attempting to objectify the prevalence of atherosclerosis in population studies.

Adult↗
PubMedDate not supplied

[Privation as a measure of the irreversibility of biological aging].

Privation (imperfection) means the error-containing part of the structural and functional organization of an organismic system. Privation is used to measure the irreversibility of aging processes. Knowing the age rate beta it is possible to estimate the privation. Using the hypothesis that the biodynamical efficiency may not be greater than the inverse age rate beta, a dimensionless number is constructed, which is given by the product of age rate beta and the theoretical lifespan T.

Aging↗
PubMedDate not supplied

[Objective assessment of biological aging in the human: results].

From a population sample of 139 healthy persons, six specially selected aging parameters were tested for their significance to vitality, by means of four mathematical models referring to the concept of vitality. As reference values, tm, is the age expressed in years when maximal vitality occurs, and the aging constant is beta, also known as an aging factor. Our results for tm extended from 16.6 to 39.6 years, depending on the respective mathematical model applied. We find a similar characteristic for the beta-values. A comparison with results in other publications on the subject, obtained by processing a considerably larger number of variables than we did, underlined the utility of our parameters. This is also shown by the quality of results we obtained by regression analysis, by the adjustment to the functions of the vitality concept and by the simplicity of the required laboratory methods of analysis.

Adult↗