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Biomedical subjects

G Sager

Publications and source records attributed to G Sager.

At least 127 records · Page 7Linked to original sources
PubMed1983

[Mathematic approximations of mass growth in pig fetuses and comparison with Homo sapiens].

Values for fetal mass growth over unequal time intervals of pregnancy as given by Brune (1972) for the domestic pig are submitted to nonlinear regressions in order to achieve mathematical approximations. Altogether 7 functions of organic growth are considered in their unbound form, as fetal mass growth is extremely slow in the 1st quarter of gravidity thus outruling the necessity of introducing an exact initial value. In contrast to many other investigations into organic growth all functions yield almost equally good results in this case. A comparison of the curves of fetal mass growth, increase and acceleration with those of man show a surprisingly close agreement. Calculation of the values of relative growth for the applied growth functions gives confirmation of this aspect, although the differences between man and domestic pig are deviating due to the functions taken into consideration. Closest junction is gained with the Mitscherlich, Sager and Richards function. For the future work of this kind interest is raised for investigating the properties of other mammals and their interrelations to each other and to man.

Animals↗
PubMed1983

[Annual growth variations of the goby Lesueurigobius friesii off Scotland based on Gibson and Ezzi data].

Samples of Lesueurigobius friesii gained and investigated by Gibson and Ezzi (1978) off the Scottish west coast comprising 5 age groups in monthly intervals show impressive seasonal variations calling for adequate mathematical treatment. For this purpose a proposal of the author (Sager 1982, 1983) as already realized for the growth behaviour of Nyctiphanes couchii with the Bertalanffy function is transferred to the Gompertz modifying this function to annual changes. The application of nonlinear regressions yields appropriate results and allows for the presentation of the modified increase function.

Animals↗
PubMed1983

[Growth relations of Rhesus monkeys (Macaca mulatta) using Van Wagenen's and Catchpole's data (1956)].

Investigations are carried out concerning the sitting height/age and the log weight/sitting height relations for the rhesus (Macaca mulatta) after dates from van Wagenen and Catchpole (1956). The formulae applied were recently given by the author for the development of the human body and parts of the skeleton (Sager 1981 a, b und 1983 a, b) and hold for the rhesus in simplified forms. This is a hint to a less differentiated form of growth that can be represented by fewer mathematical parameters than for human beings. Approximations require nonlinear regressions and are gained for the minimum of the sums of square and absolute deviations. Tables and graphs for the results are added.

Age Factors↗
PubMed1983

[Growth relations of the Japanese].

Based on data of Japanese body height and weight values published by Altman and Dittmer (1962) and compiled by Arimoto (1960) mathematical investigations into the relationship between height and age as well as log weight and height are carried out using formulas of the author already applied to measurements from the German Federal Republic and the United States of America. The main parameters show a considerable difference for the Japanese as was to be expected. Graphs give the curves for growth, increase and acceleration, supplemented by the log weight/height relation.

Adolescent↗
PubMed1983

[Weight growth of the tunny (Thunnus thynnus) as a function of time and length].

Weight growth according to the dates of SELLA (1929) was first investigated by Krüger (1973) with the Gompertz-, Bertalanffy- and Reciprocal Function. Results showed significant differences due to the lack of values after 14 years of the tunny's development. In this contribution the work of Krüger is carried on based on a much broader scale of growth functions with infinite or restricted time of weight increase. Moreover relations between the length and original and modified weights are established giving results seldom obtained in such unity with other species.

Animals↗
PubMed1983

[Growth variations of Nyctiphanes couchi using the data of Gros and Cochard (1978)].

In a paper dealing with the life cycle and growth development of Nyctiphanes couchii (crustaceans, euphausiids) off the southern coast of Britanny by Gros and Cochard (1978) from the Centre Océanologique de Bretagne graphs with the seasonal variations of the carapace length are given. Tentative growth curves were visually drawn lacking adequate mathematical formulations. In this situation a proposal of the author for taking into account annual changes (Sager 1981) is realized. Although the mathematical representation holds for all growth functions, the Bertalanffy function has been preferred as a simple form according to the relatively small number of length values.

Animals↗
PubMed1983

[Mathematical interpretation of radius growth in the human using Gindhart's (1976) data].

Values of the length growth of the human radius as gained at the Fels Research Institute for the Study of Human Development and published by Gindhart (1976) are taken into consideration for a mathematical representation. On the basis of the author's formula for the human height development computations were carried out after ascertaining the allometric relation with the height/age tables after Maaser (1974) for lack of more adequate data. For the first 10.5 years a simple power function will suffice being afterwards incorporated into the more intricate formula (Sager 1981) and complemented by an additional growth spurt term. Results may be classified as excellent for the male and good for the female.

Adolescent↗
PubMed1982

Receptor binding sites for beta-adrenergic ligands on human erythrocytes.

Affinity, specificity and kinetics for [3H]-DHA binding to human red cell ghost were determined by ultra-filtration. At 2 degree an apparent dissociation constant of 0.96 nM was found with maximum specific binding of 29 fmoles per mg protein. The low dissociation constant was confirmed by kinetic studies with a value of 0.86 nM. Propranolol and isoproterenol inhibited [3H]-DHA binding stereo specifically. Agonist potency (IPR greater than EPI greater than NE) indicated that human erythrocytes had an adrenergic receptor of beta-2 subtype. Isoproterenol in the presence of theophylline resulted in a concentration-dependent increase of intracellular cAMP levels in intact cells. Basal and maximal levels were 2.3 and 7.5 pmoles/108 cells respectively after 2.5 min stimulation. EC50 for isoproterenol was 0.27 microM. Propranolol shifted the isoproterenol concentration response curve to the right. The present results show that human erythrocytes possess recognition sites for beta-adrenergic ligands with binding characteristics similar to that of adrenergic receptors of beta-2 subtype. At least a small number of these binding sites are functionally coupled to adenylate cyclase.

Adult↗
PubMed1982

[Length growth of the North Sea plaice (Pleuronectes platessa) (author's transl)].

Values of the length growth of the North Sea plaice (Pleuronectes platessa) dating back to the decade from 1929 to 1938 and thus being free from possible pollution effects of later years are submitted to a nonlinear regression. Altogether 15 functions of organic growth were taken into account, all of them yielding asymptotic growth during the whole live span. Functions with finite growth time gave no solution. Moreover only a few functions showed a turning point leaving grave doubts about its existence. As was already the case with the Alaskan razor clam, the North Sea turbot and the Greenland cod the increase relation W = kWm/(t + t0)p proposed by the author brought the best results.

Animals↗
PubMed1982

[The length growth of the north sea sole (Solea vulgaris Quensel) and the problem of annual variations (author's transl)].

In spite of the small number of 8 averaged length values for the North Sea sole nonlinear regressions yield remarkable results for 18 out of 21 functions of organic growth. Functions implying finite growth times give rise to the assumption that length growth of Solea vulgaris theoretically comes to rest between 20 1/2 and 23 years of age. Taking up early experiences by Bückman (1934) detailed considerations are given to annual variations of growth. For this purpose the gained functions are modified to the cases of reduced or stagnating development in low temperatures.

Animals↗
PubMed1982

[Increase functions of the type DW/DT = K(T + T0)P (E - W)N and their integrals (author's transl)].

In a series of systematical investigations into increase functions the type dW/dt = ktp (E - W)n and the resulting integrals with asymptotic growth for n = 1 and finite growth time for 0 less than n less than 1 were treated (Sager 1978). The growth function was tested for several species of fishes yielding good results generally but always implying horizontal tangent at the beginning for t = 0. This is of minor importance when the birth value W0 is only a small fraction of the final value E but becomes eventually intolerable when W0/E increases. In this case the increase function must be generalized to dW/dt = k(t + t0)p (E - W)n. The consequences of this step are followed up in this paper illustrated by graphs of the behaviour of the gained growth functions.

Animals↗
PubMed1982

[About the body length frequency of 19.5 year old men after the graph of Harbeck (1960) (author's transl)].

Based on the Harbeck-graph of body length frequency for 19.5 years old men (1960), 2 methods are exercised for determining the Gaussian distribution function. At first the area arising from the frequency of length classes with the abscissa of its gravity center and the dispersion or variance are egalized to the respective values for the Gaussian curve. After that nonlinear regressions following the Paul-method (1975) are carried out minimizing the sums of the squares, absolute values and square roots of the deviations. The results of the conventional method could be improved numerically but were not discernible in graphs. Finally the subdivision into growth groups is taken into consideration.

Adult↗
PubMed1982

[Length growth of the Greenland cod (Gadus callarias female) (author's transl)].

The length of the Greenland cod Gadus callarias female is approximated by 21 functions of organic growth originating from the year 1825 up to most recent times. Only 3 functions had to be rejected due to intolerable deviations, 10 can be qualified as "good ",3 as "very good", and I as "excellent", leaving 4 as not quite satisfying. Unlimited as well as finite growth behaviour gains almost equal changes following nonlinear regression, the later group yielding 23.3 +/- 3.5 years of development in length growth. The increase function W = kWm/(t + t0)p turns out as optimal as was already the case for the Alaskan razor clam and the North Sea turbot (Sager 1980, 1981).

Animals↗
PubMed1982

[Length growth of tunny (Thunnus thynnus) according to Sella's data].

The dates of Sella (1929) for the length of the mediterranean tunny (Thunnus thynnus) already treated by Krüger (1973) are taken as a basis for mathematical approximations by 19 growth functions. For this purpose some functions had to be modified to allow for a non-horizontal tangent at the beginning. As the available length values cease with 14 years of age, there is much room for the theoretical final length giving a good insight into the characteristics of the different approximations. Surprisingly the functions with final growth time yield values with only small deviations from each other except for one calculation thus hinting to a theoretical growth duration of about 25 +/- 2 years.

Age Factors↗
PubMed1982

[Mathematic formulation of weight/height somatograms of Hellbrügge and Vogt (1961) and comparison with data of Maaser (1971)].

The height/weight relations as given by Hellbrügge and Vogt (1961) are brought into a mathematical formulation following the procedure already applied by the author to the Maaser tables of 1974 (Sager 1981 a). To this purpose the quasilinear behaviour of log weight to height from 100 cm upward as similarly used by Krüger (1975) is complemented by a function thus incorporating the values from birth to about 2 years of age and correcting the relation thereafter. Nonlinear regressions are exercised and compared with the results from the dates of Maaser (1974) showing close agreement in the first years of life and small but increasing deviations for the weight from 5 (female) or 8 to 9 (male) years respectively.

Body Height↗
PubMed1982

[Mathematical interpretation of the length/age tables of Hellbrügge and Vogt (1961)].

The height/age tables of Hellbrügge and Vogt (1961) for human growth from birth to adolescence are taken as a basis for mathematical presentation analogous to the method exercised by the author (Sager 1981 a) with the tables of Maaser (1974). The structures of the formulas for the prepuberal phase, the transition span and the final growth behaviour remain the same whilst parameters change according to acceleration and regional as well as social-economical circumstances of the different age classes.

Adolescent↗