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L Piantanelli

Publications and source records attributed to L Piantanelli.

15 recordsLinked to original sources
PubMed1992

Age-related alterations of isoproterenol-stimulated adenylyl-cyclase activity are partially corrected by thymic graft.

Previous experimental results have demonstrated progressive impairments in beta-adrenergic responsiveness with advancing age. Beta-adrenoceptors are involved in the alterations as their density progressively decreases during aging. Alterations in both in vivo responsiveness and receptor density are corrected by neonatal thymic grafts. In the present paper adenylyl-cyclase (AC) activity has been studied in the same animal models used before. Results show that no statistically significant changes can be observed when AC is assayed in absence of beta-adrenergic stimulation. On the contrary, when assayed after Isoproterenol stimulation, AC activity shows a shift of the peak and a decrease of its height in aged animals. A neonatal thymus grafted into old recipients one month before the experiment was performed, is capable of correcting the altered height of the peak but not the peak concentration.

Adenylyl Cyclases↗
PubMed1992

Modelling survivorship kinetics: a two-parameter model.

A mathematical model of survivorship kinetics is presented. It takes into account both deterministic and stochastic aspects of survival curves. Earlier reports [Piantanelli: Arch Gerontol Geriatr 1986;5:107-118; Piantanelli: Ann NY Acad Sci 1988; 521:99-109] described a model capable of making distinct predictions on the mean and standard deviation of an index of physiological function, fitting data even in the tail of survivorship curves, and accounting for the selection of the cohort at advanced ages. However, it contains four parameters whose biological interpretation is unclear. In the present paper we propose a modification of the model which maintains the main characteristics of the previous one and, in addition, results in two significant improvements. First, the number of free parameters is reduced to only two, making much easier both their estimation and interpretation, particularly when the model is applied to data from various animal groups manipulated in different ways. Second, it is possible to relate the parameters to well-defined deterministic and stochastic factors: specifically, a deterministic component describing the environmental and genetic influence on physiological functions, and a stochastic component representing the fluctuating interactions of the living organism and its environment.

Aging↗
PubMed1991

Role of triiodothyronine in down-regulation and recovery of lymphocyte beta-adrenoceptors in thyroidectomized patients.

Thyroid function modulates beta-adrenergic sensitivity through the regulation of beta-adrenoceptor density. In particular, thyroidectomy decreases and thyroid hormone injections increase beta-adrenoceptor density on human lymphocytes. In the present paper the relationship between receptor modifications and thyroid hormone levels has been studied in human lymphocytes from patients after thyroidectomy. The patterns of early changes as well as recovery trends have been investigated. Results show a statistically significant fall in receptor density, parallelled by a decrease in T3 levels, 1-3 days after thyroidectomy. Recovery of receptor density is observed 5-8 days after surgical intervention and is accompanied by increased T3 levels. There is a positive correlation between receptor density and T3 levels. On the contrary, no statistically significant correlation was observed for receptor density and T4 levels. The time course of disappearance and recovery of receptor density and that of T3 levels have also been analyzed with the aid of a mathematical model fitting experimental data. On this basis, the hypothesis that both down-regulation and subsequent recovery of beta-adrenoceptor density are driven by the fall and rise of T3 is suggested. Data are also discussed in relation to experimental results we have obtained in animal studies.

Adult↗
PubMed1991

Thymus-induced recovery of age-related decrease of brain cortex alpha- and beta-adrenoceptors.

It has previously been demonstrated that thymus exerts a regulatory influence on beta-adrenergic system during aging. In particular, it has been shown that thymus can correct the beta-adrenoceptor density decrease in old mice. In the present paper results of experiments are reported dealing with the influence of the thymus on alpha-adrenoceptors of mouse brain cortex. Both subtypes of alpha-adrenoceptors are studied separately, using different labelled ligands. Results show that alpha 1-adrenoceptor density decreases in old animals, while alpha 2-adrenoceptor density does not change significantly. A neonatal thymus grafted into old recipients is capable of correcting the alteration observed in old mice. The differential impairment of alpha-adrenoceptors resembles that one previously observed on beta-adrenoceptors, where beta 1-type decreases in number during aging with a parallel decrease of adenylyl-cyclase activity, while beta 2-type remains unchanged.

Adenylyl Cyclases↗
PubMed1990

Influence of age on the thyroid hormone-induced up-regulation of beta-adrenoceptors in mouse brain cortex.

The influence of ageing on the ability of the brain cortex beta-adrenoceptors to be regulated by very short stimulation with thyroid hormones has been investigated. Experiments were performed in 3-, 10-, 17- and 22-month-old mice using both thyroxine (T4) and triiodothyronine (T3) as stimulators and analyzing beta-adrenergic receptor characteristics 15 and 60 min after hormone injection. Results showed that a statistically significant up-regulation is present in both young and old mice when treated with T3. On the contrary, after T4 injection only 3-month-old animals respond to such a short-term treatment, whereas older adult and old animals showed not statistically significant changes. Thus, the impairment in the T4-induced up-regulation starts already in adult mice and does not seem to further increase progressively with advancing age. From these findings it is suggested that the lack of responsiveness of beta-adrenoceptors to T4 but not to T3 stimulation in adult and old mice may be due to relatively early impairment in the transformation of T4 into T3.

Age Factors↗
PubMed1978

Age-dependence of isoproterenol-induced DNA synthesis in submandibular glands of BALB/c mice.

The age-dependency of isoproterenol (IPR) induced DNA synthesis was investigated in different organs of Balb/c mice. Although modifications of the physiological rate of DNA synthesis after IPR injection occurred also in liver and spleen, a quasi-linear decrease of the peak of IPR response with advancing age was observed only in submandibular glands. Such a decrease was observed when animals were injected with 10(-4) g IPR per g body weight, lower doses being unable to discriminate between young and old mice. In spite of some differences between mice and rats, the early appearance and linearity of the age-dependency remain common features of IPR response.

Age Factors↗
PubMed1978

Thymus-dependent reversibility of physiological and isoproterenol evoked age-related parameters in athymic (nude) and old normal mice.

In order to assess the relationship between the thymus and aging processes, a linear age-dependent parameter in mice such as the response of the submandibular gland to an injection with isoproterenol has been evaluated in athymic (nude) and thymectomized Balb/c mice. The IPR-induced DNA synthesis is reduced in both experimental groups when compared to untreated normal littermates and is recovered by grafting a neonatal thymus. Moreover, the impairment of IPR response in old animals is recovered to young levels by grafting one neonatal thymus one month before test. Neonatal thymus grafts in old recipients are also able to correct their abnormal serum levels of triiodothyronine and insulin. The influence of neonatal thymus on such non-immunological and age-related parameters suggests that this gland can control aging processes, probably through its implication with the endocrine system.

Age Factors↗
PubMed1977

Differential effect of pregnancy or gestagens on humoral and cell-mediated immunity.

The reactivity of spleen lymphocytes in a mixed lymphocyte culture and the in vivo PFC response to sheep erythrocytes have been evaluated in pregnant female mice and data compared with those observed in virgin sexually mature female mice daily treated either with progesterone or human chorionic gonadotropin (HCG) or human prolactin. The mixed lymphocyte reactivity is depressed at mid-pregnancy, whereas PFC response is increased. Comparable immunological modifications have been found in mice treated with HCG, but not in animals treated with progesterone or prolactin. The similarity between HCG treatment and pregnancy suggests that the rate of gonadotropin release may be one of the earliest events responsible for the immunological disturbances present during pregnancy, although its action on the lymphoid system seems to require the presence of the ovary. From these data and from the observation that HCG increases the PFC response also in thymusless nude female mice, it can be deduced that it acts on both T and B cells.

Animals↗
PubMed1977

Differential effect of pancreatectomy on humoral and cell-mediated immune responses.

Cell-mediated immune reactions, such as allogenic skin-graft rejection and PHA or MLC responses, and antibody synthesis against different antigens (sheep erythrocytes, Brucella antigen, bovine serum albumin) have been evaluated in rats suffering from experimentally-induced diabetes and in age-matched sham-treated controls. Cell-mediated immune reactions are strongly depressed diabetic rats. The cellularity of the thymus and of thymus-dependent areas and the number of peripheral blood lymphocytes is significantly reduced in pancreatectomized rats. Moreover, the immunological recovery from heavy cortisonization is also greatly impaired. Daily treatment with insulin may prevent these immunological alterations. By contrast, antibody responses in diabetic rats are not quantitatively altered in respect to either the number of antibody producing cells in the spleen or the circulating antibody titres. The discrepancy between the abnormality of cell-mediated immune reactions in diabetic rats and their physiological capacity to synthetize antibodies suggests that the sensitivity to an insulin-deprived environment is present only in a definite, although yet undefined, subpopulation of lymphoid cells rather than in the whole lymphoid system.

Animals↗