Biomedical subjects

G Cognini

Publications and source records attributed to G Cognini.

5 recordsLinked to original sources

PubMed1986

A mathematical model of survival kinetics. II. Parameter estimation.

Procedures for the estimation of the four parameters of a new mathematical model of survival and mortality kinetics are given. A formulation of the model has been found which had the advantage of maintaining three of four parameters independent of the unit chosen for the age; in addition, two of these parameters have values falling in a narrow range, even when the model is applied to rather different curves. Since, in any problem of this type, the initial estimate of the parameters plays a major role in the achievement of good final estimates, some simple methods of estimation are indicated based upon the characteristics of the function. The initial estimates may enter three different types of procedures; the best one can be chosen according to the precision of the initial estimates. The method is capable of fitting both survivorship and dying functions directly to the empirical data. An interactive approach to the computer facilities has been used as at each step the operator has to decide whether or not to apply a corrective factor. Goodness of fit, usually high, is estimated by chi 2 test.

Aging↗

PubMed1985

Acebutolol-induced decrease of mononuclear leukocyte beta-adrenoceptors in hypertension.

The regulatory action exerted on receptors by acebutolol, a cardioselective beta-blocker containing intrinsic sympathomimetic activity, has been investigated. beta-Adrenoceptor affinity and density of human mononuclear leukocytes were assayed in hypertensive patients before and after treatment with 400 mg/day acebutolol. While receptor affinity showed no changes between pre- and post-treatment values, a statistically significant decrease has been demonstrated in receptor density following treatment. Blood pressure and heart rate were also measured in order to test the efficacy of the administered drug. All these parameters showed a fall in the post-treatment values. It is concluded that the partial agonist acebutolol, in spite of the fact that it acts clinically as a beta-blocker, has the regulatory mechanism characteristic of agonists.

Acebutolol↗

PubMed1984

Atenolol-induced regulation of leukocyte beta 2-adrenoceptors in hypertension.

beta 2-Adrenoceptor characteristics of human mononuclear leukocytes were assayed in hypertensive patients before and after treatment with 100 mg/day atenolol. While no changes have been observed in receptor affinity, a statistically significant increase (36%) has been demonstrated in receptor density following treatment. Blood pressure and heart rate were also measured in order to test the efficacy of the administered drug. All these parameters showed a fall in the post-treatment values. It is concluded that at therapeutic concentration, beta 2-adrenoceptors undergo up-regulation by atenolol in spite of its cardioselectivity. Such a regulation, which may represent a fundamental step in the mechanism leading to withdrawal syndrome, may, therefore, be suggested being quite widespread.

Adult↗

PubMed1983

Decreased beta-adrenergic receptor density in mononuclear leukocytes from thyroidectomized patients.

Beta-adrenergic receptor characteristics were investigated in peripheral blood mononuclear leukocytes taken from patients before and after partial thyroidectomy. In order to discriminate the effect of surgical stress per se from that of thyroidectomy, the analysis was also performed on patients before and after cholecystectomy. Receptor characteristics were determined by using dihydroalprenolol as ligand in direct equilibrium binding experiments. The binding affinity showed no changes either when two different surgical treatments were compared or when the same patient was analysed before and after the operation. On the contrary, a significant decrease in receptor density was found in thyroidectomized patients when compared pre- and post-operatively. This fall in receptor number seems to be linked with thyroid function since no statistically significant changes were observed in cholecystectomized patients in relation to surgical operation. This view is further supported by data on T3 serum levels, which show a significant fall after thyroidectomy but no statistically significant modifications after cholecystectomy. It is concluded that beta-adrenoceptor modulation plays an important role in the relationship between thyroid and beta-adrenergic system.

Adenoma↗

PubMed1980

[High and low affinity beta adrenergic receptor sites from submandibular glands of mice].

Beta-adrenergic receptors from submandibular glands of mice were studied by equilibrium binding experiments. Due to the fact that some discrepancies were previously observed among different author data, we compared two methods for non specific binding substruction, that represents the major source of errors in such experiments. Data were obtained strongly suggesting the presence of multiple population of binding sites and/or negative cooperativity.

Animals↗