Cell-oriented modeling of angiogenesis.

Due to its significant involvement in various physiological and pathological conditions, angiogenesis (the development of new blood vessels from an existing vasculature) represents an important area of the actual biological research and a field in which mathematical modeling proved particularly useful in supporting the experimental work. In this paper, we focus on a specific modeling strategy, known as "cell-centered" approach. This type of mathematical models work at a "mesoscopic scale," assuming the cell as the natural level of abstraction for computational modeling of development.

Anatomical basis of hypoxic and hyperoxic injuries to the centres of cardiorespiratory regulation.

The aim of the present paper is to briefly review the changes occurring in the nucleus tractus solitarii and carotid body in response to hypoxic and hyperoxic injuries. Selective alterations of dendrites and Fos-immunoreactivity of neurons have been observed in the subnucleus gelatinosus of the nucleus tractus solitarii of adult subjects dying after hypoxic-ischaemic injury. The selective vulnerability of this portion of the nucleus tractus solitarii may be explained mainly with reference to the vascularization of medullary tegmentum.

The pro-angiogenic activity of urotensin-II on human vascular endothelial cells involves ERK1/2 and PI3K signaling pathways.

Human vascular endothelial cells express the urotensin-II (U-II) receptor and exhibit a strong in vitro angiogenic response to the peptide. Thus, in the present study an in vitro model, based on human umbilical vein endothelial cells (HUVEC) cultured on Matrigel, was used to characterize more in detail the signaling pathways that control the pro-angiogenic action of U-II. The activation of the U-II receptor (UT) was associated with an increase of intracellular calcium concentration.

Prolonged zidovudine administration induces a moderate increase in the growth and steroidogenic capacity of the rat adrenal cortex.

Zidovudine (AZT) is an antiretroviral drug widely used in the treatment of human immunodeficiency virus (HIV)-infected patients, whose prolonged administration was found to cause toxic lesions in cardiomyocytes in humans and experimental animals. Alterations in adrenocortical secretion were frequently observed in HIV patients, but it is not clear whether medication is involved in the production of these complications. Hence, we studied in vivo and in vitro, the effects of AZT on the rat adrenal cortex.

Up-regulation of adrenomedullin receptor gene expression in activated local stem cells during rat adrenal regeneration.

Previous studies showed that adrenomedullin (AM) gene expression was up-regulated in the regenerating rat adrenal cortex after enucleation and contra-lateral adrenalectomy, the effect being significant at day 1 after surgery and peaking between days 3 and 7. Using the same experimental model, we investigated by real time-polymerase chain reaction the mRNA expression of the AM receptor components: calcitonin receptor-like receptor (CRLR) and receptor activity-modifying proteins (RAMP)2 and 3. At time 0 (60 min after enucleation; control group), the CRLR mRNA content was approximately 2- and 5-fold higher than that of RAMP2 and RAMP3, respectively.

Up-regulation of adrenomedullin gene expression in the regenerating rat adrenal cortex.

Adrenomedullin (AM) is an endogenous regulatory peptide that exerts growth-promoting action in several normal and neoplastic tissues, and we investigated whether its gene expression changes during rat adrenal regeneration after enucleation and contra-lateral adrenalectomy. Regenerating adrenals were collected at day 0 (just after enucleation; control rats), 1, 3, 7, 14 and 28 after surgery. The immunocytochemical assay of PCNA (proliferating cell nuclear antigen) index confirmed that the early stages of regeneration can be divided into an initial differentiation period (from day 0 to day 3) and a subsequent high proliferative period (days 5 and 7) followed by a decrease in the proliferation activity.

IGF-I enhances cortisol secretion from guinea-pig adrenal gland: in vivo and in vitro study.

Insulin-like growth factor (IGF)-I is a ubiquitously synthesized peptide that, along with IGF-II, acts via the IGF-R type I receptor. IGF-I and its receptor are expressed in the adrenal gland of humans and bovines, the secretion of which they seem to stimulate. As in humans and cows, the main glucocorticoid hormone secreted by guinea-pig adrenals is cortisol, and hence we have studied the adrenocortical effects of IGF-I in this species.

Galanin enhances corticosterone secretion from dispersed rat adrenocortical cells through the activation of GAL-R1 and GAL-R2 receptors coupled to the adenylate cyclase-dependent signaling cascade.

Galanin is a regulatory peptide, which acts via three subtypes of receptors, named GAL-R1, GAL-R2 and GAL-R3. Reverse transcription-polymerase chain reaction demonstrated the expression of GAL-R1 and GAL-R2, but not GAL-R3 mRNAs in dispersed rat adrenal zona fasciculata-reticularis (inner) cells. The immuno-blockade of GAL-R1 and GAL-R2, but not GAL-R3, decreased the binding of [3H]galanin to dispersed cells, a complete inhibition being obtained only by the simultaneous blockade of both receptor subtypes.

Ouabain chronic infusion enhances the growth and steroidogenic capacity of rat adrenal zona glomerulosa: the possible involvement of the endothelin system.

Ouabain, an inhibitor of the Na+/K+-ATPase, has been reported to affect the secretory activity of the adrenal cortex, and especially of zona glomerulosa (ZG). However, conflicting results were obtained, depending on the experimental condition used since ouabain appears to interact with angiotensin-II (Ang-II) and its action to be influenced by the electrolyte balance. Hence, we investigated the effects of prolonged (4-month) infusion with ouabain on the rat adrenal cortex.

Effects of some endocrine disruptors on the secretory and proliferative activity of the regenerating rat adrenal cortex.

The effects of some endocrine disruptors that possess estrogen-like activity on the secretion and growth of regenerating rat adrenal cortex have been investigated in ovariectomized (OVX) and sham-OVX rats. As reference groups, dexamethasone (Dx)-administered sham-OVX and 17beta-estradiol-administered OVX animals were used. Dx, estradiol and endocrine disruptors were subcutaneously injected daily at a dose of 3 nmoles/100 g for 10 consecutive days after surgery, and adrenal enucleation was performed on day 5 of the experiment.

Angiogenic response induced by acellular femoral matrix in vivo.

We investigated the angiogenic response induced by acellular femoral matrices implanted in vivo on to the chick embryo chorioallantoic membrane (CAM), a useful model for such investigation. The results showed that acellular matrices were able to induce a strong angiogenic response, comparable with that of fibroblast growth factor-2 (FGF-2), a well-known angiogenic cytokine. The angiogenic response was further increased when exogenous FGF-2 or transforming growth factor beta-1 (TGF-beta1) was added to the matrices and inhibited by the addition of anti-FGF-2 or anti-TGF-beta1 antibodies.

Arginin-vasopressin regulates proliferative activity of the regenerating rat adrenal cortex.

Enucleation-induced adrenal regeneration is a classic model to investigate adrenocortical proliferation in vivo, which is dependent not only on pituitary ACTH release, but also on various other neural and endocrine signals. Arginin-vasopressin (AVP), mainly acting via V1 receptors, regulates hypothalamic-hypophyseal-adrenal axis function, acting on both its central and peripheral branches. Here, we studied whether endogenous AVP system modulates rat adrenal regeneration.

Orexins modulate the growth of cultured rat adrenocortical cells, acting through type 1 and type 2 receptors coupled to the MAPK p42/p44- and p38-dependent cascades.

Orexin A and B are hypothalamic peptides that act through two subtypes of receptors named OX1-R and OX2-R. The OX1-R almost exclusively binds orexin-A, whereas OX2-R is non-selective for both orexins. We previously found that rat adrenocortical cells express both orexin-receptor subtypes, and orexin-A stimulates corticosterone secretion from dispersed adrenocortical cells acting via the OX1-R.

Effects of met-enkephalin on cell proliferation in different models of adrenocortical-cell growth.

Met-enkephalin (met-Enk) is an opioid peptide that acts via three main subtypes of receptors referred to as mu (mu)-, delta (delta)- and zeta (zeta)-receptor. While the first two receptor subtypes mediate the classic opioid effects of met-Enk, zeta-receptors are reported to be involved in the non-opioid actions of the peptide, i.e.

G protein receptors 7 and 8 are expressed in human adrenocortical cells, and their endogenous ligands neuropeptides B and w enhance cortisol secretion by activating adenylate cyclase- and phospholipase C-dependent signaling cascades.

Neuropeptides B and W (NPB and NPW) are regulatory peptides that act via two subtypes of G protein-coupled receptors, named GPR7 and GPR8. RT-PCR demonstrated the expression of these receptors in both zona glomerulosa and zona fasciculata-reticularis (ZF/R) cells of the human adrenal cortex. NPB and NPW did not affect aldosterone secretion from dispersed zona glomerulosa cells but enhanced cortisol production from ZF/R cells, NPB being more effective than NPW.

Ghrelin inhibits FGF-2-mediated angiogenesis in vitro and in vivo.

Recent evidence indicates that ghrelin, an endogenous ligand of the growth hormone secretagogue receptor (GHS-R), is highly expressed in the cardiovascular system, and in this study we addressed the possibility that ghrelin may affect angiogenesis in vitro and in vivo. Reverse transcription-polymerase chain reaction showed that human umbilical vein endothelial cells (HUVECs) express ghrelin and GHS-R mRNAs. Ghrelin inhibited FGF-2-induced proliferation of HUVECs cultured in vitro, the maximal effective concentration being 10(-8) M, and this effect was annulled by the GHS-R antagonist D-Lys3-growth hormone releasing peptide-6.

Adrenomedullin (AM) and AM receptor type 2 expression is up-regulated in prostate carcinomas (PC), and AM stimulates in vitro growth of a PC-derived cell line by enhancing proliferation and decreasing apoptosis rates.

Adrenomedullin (AM) is a hypotensive peptide, that acts via the calcitonin receptor-like receptor (CRLR), whose interaction with the subtypes 2 and 3 of a family of receptor activity-modifying proteins (RAMP) gives rise to two distinct AM receptors, named AM1 and AM2 receptors. AM derives from the post-translational proteolytic cleavage of pro(p)AM, the last step of which involves the conversion of the inactive AM to active AM by the peptidyl-glycine alpha-amidating monooxigenase (PAM). Compelling evidence suggests that AM, in addition to exerting its well-known regulatory action on blood pressure and water and electrolyte balance, also possesses a growth promoting effect in several normal and neoplastic tissues, including human prostate.

In vitro culture of rat neuromicrovascular endothelial cells on polymeric scaffolds.

Polyphosphazenes are polymers possessing a skeleton composed of alternating phosphorous and nitrogen atoms, and two side-moieties linked to each phosphorous atom. Polyphosphazenes with amino acid esters as side-moieties are biocompatible and biodegradable polymers. Two polyphosphazenes, poly[bis(ethyl alanate) phosphazene] and poly[(ethyl phenylalanate)0.

Ghrelin enhances the growth of cultured human adrenal zona glomerulosa cells by exerting MAPK-mediated proliferogenic and antiapoptotic effects.

Ghrelin is an endogenous ligand of the growth hormone secretagogue receptor (GHS-R), two subtypes of which have been identified and named GHS-R1a and GHS-R1b. Evidence has been provided that ghrelin and its receptors are expressed in the adrenal gland, and we have investigated the possible role of the ghrelin system in the functional regulation of the human adrenal cortex. Reverse transcription-polymerase chain reaction detected the expression of both subtypes of GHS-Rs exclusively in the zona glomerulosa (ZG).

Beacon[47-73] inhibits glucocorticoid secretion and growth of cultured rat and human adrenocortical cells.

Evidence has been recently provided that beacon, an ubiquitin-like protein overexpressed in the hypothalamus of Israeli sand rat, is also expressed in several endocrine glands of the Wistar rat, including adrenal cortex. Moreover, it has been shown that the in vivo administration of beacon[47-73] (hereinafter, beacon) evokes within 60 min a marked decrease in the plasma concentrations of ACTH and corticosterone. Hence, we have investigated the effect of beacon (4x10(-9) or 4x10(-7) M) on the secretion and growth of cultured rat and human zona fasciculata/reticularis (ZF/R) cells.

Effect of ghrelin on the apoptotic deletion rate of different types of cells cultured in vitro.

Evidence indicates that ghrelin, an endogenous ligand of the growth hormone secretagogue receptor, controls the growth of several human and rat cell types cultured in vitro. Hence, we have investigated, by using both TUNEL and ELISA assays, the effects of 10(-8) M ghrelin on the basal apoptotic deletion rate of rat osteoblasts and thymocytes, rat and human adrenocortical cells, human umbilical vein endothelial cells, and human aldosteronoma cells cultured in vitro, as well as of the human adrenocortical carcinoma-derived cell lines NCI-H295 and SW-13. Both assays consistently showed that ghrelin did not affect apoptotic rate of normal rat and human cells, but significantly enhanced apoptotic deletion in aldosteronoma, NCI-H295 and SW-13 cell cultures.

Zidovudine-induced alterations in the heart and vascular smooth muscle of the rat.

Objective: We investigated the effects of zidovudine (AZT) on cardiac and vascular smooth muscle function and morphology in rats.

Methods: Four adult male Wistar-Kyoto rats received AZT in drinking water for 240 days; four rats served as controls. Echocardiographic examination and systolic blood pressure (SBP) measurement were performed.

Effects of galanin on proliferation and apoptosis of immature rat thymocytes.

Evidence indicates that some regulatory peptides (endothelins, cholecystokinin and VIP) are involved in the control of thymus growth, and we have investigated whether galanin may be included in this group of peptides. In fact, galanin, a 29-amino acid peptide acting through three subtypes of G protein-coupled receptors (GalR1, GalR2 and GalR3), seems to play a role in the control of the immune system. Reverse transcription (RT)-polymerase chain reaction (PCR) allowed the detection of galanin, GalR1 and GalR3 mRNAs in the thymus cortex of immature (20-day-old) rats, while GalR2 expression was very weak or absent.

Adrenomedullin and its receptors are expressed in the zona glomerulosa of immature and adult rat adrenals: evidences of upregulation of ADM system in immature glands.

Evidence has been provided that adrenomedullin (ADM) stimulates the proliferative activity of adult rat adrenal zona glomerulosa (ZG). However, the selective ADM receptor antagonist ADM(22-52), although being able to block ADM effect, was per se ineffective. In contrast, in the companion paper, we showed that ADM(22-52) depresses the proliferation rate of ZG in 20-day-old rats, suggesting the involvement of endogenous ADM system in adrenal maturation.

Expression and function of vasoactive intestinal peptide, pituitary adenylate cyclase-activating polypeptide, and their receptors in the human adrenal gland.

VIP and pituitary adenylate cyclase-activating polypeptide (PACAP) are two regulatory peptides that possess remarkable amino acid sequence homology and act through common receptors, named PAC(1), VPAC(1), and VPAC(2). PAC(1) receptor is selective for PACAP, whereas VPAC(1) and VPAC(2) receptors bind both VIP and PACAP. We have investigated the expression and function of VIP, PACAP, and their receptors in the zona glomerulosa (ZG), zonae fasciculata and reticularis, and adrenal medulla (AM) of the human adrenal cortex.