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S Nicosia

Publications and source records attributed to S Nicosia.

At least 37 records · Page 2Linked to original sources
PubMed1997

Characterization of the Ca2+ responses evoked by ATP and other nucleotides in mammalian brain astrocytes.

1. This study was aimed at characterizing ATP-induced rises in cytosolic free calcium ion, [Ca2+]i, in a population of rat striatal astrocytes loaded with the fluorescent Ca2+ probe Fura2, by means of fluorescence spectrometry. 2. ATP triggered a fast and transient elevation of [Ca2+]i in a concentration-dependent manner. The responses of the purine analogues 2-methylthio-ATP (2-meSATP), adenosine-5'-O-(2-thiodiphosphate) (ADP beta S), as well as uridine-5'-triphosphate (UTP) resembled that of ATP, while alpha, beta-methylene-ATP (alpha, beta-meATP) and beta, gamma-methylene-ATP (beta, gamma-meATP) were totally ineffective. 3. Suramin (50 microM) had only a minor effect on the ATP response, whereas pyridoxal phosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) (5 microM) significantly depressed the maximum response. 4. Extracellular Ca2+ did not contribute to the observed [Ca2+]i rise: removing calcium from the extracellular medium (with 1 mM EGTA) or blocking its influx by means of either Ni2+ (1 mM) or Mn2+ (1 mM) did not modify the nucleotide responses. 5. Furthermore, after preincubation with 10 microM thapsigargin, the nucleotide-evoked [Ca2+]i increments were completely abolished. In contrast, 10 mM caffeine did not affect the responses, suggesting that thapsigargin-, but not caffeine/ryanodine-sensitive stores are involved. 6. Both application of the G-protein blocker guanosine-5'-O-(2-thiodiphosphate) (GDP beta S) (1 mM) and preincubation with pertussis toxin (PTx) (350 ng ml-1) partially inhibited the nucleotide-mediated responses. Moreover, the phospholipase C (PLC) inhibitor U-73122, but not its inactive stereoisomer U-73343 (5 microM), significantly reduced the ATP-evoked [Ca2+]i rise. 7. In conclusion, our results suggest that, in rat striatal astrocytes, ATP-elicited elevation of [Ca2+]i is due solely to release from intracellular stores and is mediated by a G-protein-linked P2Y receptor, partially sensitive to PTx and coupled to PLC.

Adenosine Triphosphate↗
PubMed1997

Inhibition of airway constriction by opioids is different down the isolated bovine airway.

BACKGROUND: Opioid agonists attenuate in isolated airways contractile responses to electrical field stimulation (EFS), and this attenuation is mediated by opioid receptors. Differences exist in the density of muscarinic and beta-adrenergic receptors between large and small airways. The authors hypothesized that the density of opioid receptors may also be different down the airway. METHODS: The effects of three selective opioid agonists (mu, kappa, delta) on EFS-induced contractions were compared between isolated bovine sublobar (4- or 5-mm inner diameter) and segmental (2- or 3-mm inner diameter) bronchial rings and between trachealis strips and bronchial rings. RESULTS: D-Ala2-N-MePhe4-Gly-ol5 enkephalin (DAMGO; 10(-5) M), a mu-opioid agonist, attenuated EFS-induced contractions of isolated sublobar and segmental bronchial rings at low stimulating frequencies of 0.5 Hz (P < 0.001), 2 Hz (P < 0.001), and 8 Hz (P < 0.001), but not at 32 Hz (P = 0.071). The inhibitory effect of DAMGO was antagonized by naloxone (10(-5) M) (P = 0.025). The selective kappa-opioid agonist U-50488 H (10(-5) m) attenuated EFS-induced contractions at 32 Hz (P = 0.008) and 8 Hz (P = 0.045), but not at 2-Hz (P = 0.893) or 0.5-Hz (P = 0.145) contractions. The inhibitory effects of 10(-5) M U-50488 H were not antagonized by the highly selective kappa-antagonist 2,2'-[1,1'-biphenyl] 4,4'-diyl-bis [2-hydroxy-4,4-dimethyl]-morpholinium (nor-BNI; 10(-5) M; P = 0.216) or naloxone (10[-5]) M; P = 0.065). The selective delta-agonist D-penicillamine2-D-penicillamine5-enkephalin (DPDPE) (10(-5) M) had no inhibitory effects (P = 0.256). The inhibitory effects of the selective mu-opioid agonist DAMGO were smaller (P < 0.001) and those of U-50488 H larger (P < 0.001) in trachealis strips compared with bronchial rings. CONCLUSIONS: The attenuation of EFS-induced contractions by DAMGO in isolated bovine bronchi was mediated by prejunctional opioid receptors. In contrast, the inhibitory effect of U-50488 H was probably not mediated by opioid receptors in the bronchi.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1997

Functional magnetic resonance imaging: a potential tool for the evaluation of spinal cord stimulation: technical case report.

OBJECTIVE AND IMPORTANCE: The management of chronic pain of spinal origin continues to represent a challenge for neurosurgeons. Spinal cord stimulation for chronic intractable pain is an effective therapy in approximately 50% of patients. The present study uses a novel imaging approach, functional magnetic resonance imaging (fMRI), to examine the central effects of spinal cord stimulation. CLINICAL PRESENTATION: Three patients, each with a chronic history of intractable pain, were treated at the Toronto Hospital with a trial of dorsal column stimulation (DCS). For all patients, significant improvement in pain symptoms was achieved with DCS. INTERVENTION: fMRI on a 1.5-T conventional magnetic resonance system was used to study the effects of DCS in these patients. Images were collected while the stimulator was activated and deactivated. CONCLUSION: This report is the first to describe the cerebral effects of exogenous spinal cord stimulation with fMRI. fMRI allows for the objective examination of the effects of DCS and may provide an objective means of evaluating the efficacy of DCS as a therapy for intractable pain of spinal origin.

Adult↗
PubMed1997

The Role of Selective Lymphadenectomy in Breast Cancer.

BACKGROUND: Axillary node dissection is considered a standard staging procedure in patients with breast cancer. The procedure is associated with significant morbidity and provides pathologists with many lymph nodes to evaluate. METHODS: A total of 174 women participated in a trial that included preoperative lymphoscintigraphy and intraoperative lymphatic mapping using a combination of a vital blue dye and radiocolloid mapping. RESULTS: The intraoperative lymphatic mapping correctly identified a sentinel lymph node (SLN) in 160 (92%) of 174 patients. One skip metastasis (0.7%) occurred in 136 women who had a subsequent complete node dissection. CONCLUSIONS: Lymphatic mapping and SLN biopsy using a combination of mapping techniques provide accurate nodal staging for women with breast cancer. With this technique, approximately 70% to 80% of women with no axillary metastases could be spared the morbidity of a complete node dissection.

Journal Article↗
PubMed1996

Lymphatic mapping and sentinel node biopsy in the patient with breast cancer.

OBJECTIVES: To identify the sentinel lymph node(s) (SLN[s]) (the first node[s] draining the primary tumor in the regional lymphatic basin) in patients with invasive breast cancer and to test the hypothesis that the histologic characteristics of the SLN predict the histologic characteristics of the remaining lymph nodes in the axilla. DESIGN: A prospective trial. PARTICIPANTS: Sixty-two patients with newly diagnosed invasive breast cancers. INTERVENTION: Patients underwent intraoperative lymphatic mapping using a combination of a vital blue dye and filtered technetium-labeled sulfur colloid. The SLN was identified and removed, followed by a definitive cancer operation, including a complete axillary node dissection. MAIN OUTCOME MEASURE: The metastatic distribution in the axilla was determined in patients with occult nodal disease. RESULTS: The SLN was successfully identified in 57 (92%) of 62 patients using the 2 lymphatic mapping procedures. After localization, 18 patients (32%) were found to have metastatic disease, and the SLN tested positive in all 18 patients. There were no "skip" metastases, defined as an SLN that tested negative with higher nodes that tested positive. In 12 (67%) of 18 patients with metastatic disease, the SLN was the only site of disease. The metastatic distribution significantly favored SLN involvement. Among subjects with discordant nodal involvement, the probability of observing the distribution of SLN involvement by chance is very small (P<.001). CONCLUSIONS: This study confirms that lymphatic mapping is technically possible in the patient with breast cancer and that the histologic characteristics of the SLN probably reflect the histologic characteristics of the rest of the axillary lymph nodes. The procedure also allows the pathologist to focus the histologic examination on 1 or 2 nodes, potentially increasing the yield of positive dissections and the accuracy of staging.

Axilla↗
PubMed1996

Effect of the new calcium antagonist lercanidipine and its enantiomers on the migration and proliferation of arterial myocytes.

The in vitro effects were investigated of the new dihydropyridine calcium antagonist (CA) lercanidipine and its enantiomers on arterial myocyte (smooth muscle cell; SMC) migration and proliferation as related to L-type calcium channel inhibition. Lercanidipine and its enantiomers inhibited the replication and migration of arterial myocytes in concentration ranging from 10 to 50 microM. The antiproliferative effect of lercanidipine, evaluated as cell number, was dose dependent, with a potency similar to that of lacidipine and nifedipine, and was unrelated to the stereoselectivity of enantiomers to bind L-type calcium channels. The cell doubling time increased with drug concentration < or = 122 versus 38 h for controls. The cell growth inhibition induced by lercanidipine and its enantiomers was reversible. Lercanidipine dose dependently decreased [3H]thymidine incorporation into DNA; the (R)-enantiomer, displaying the lowest CA activity, was the most potent in this respect. The tested compounds were able to inhibit fibrinogen-induced myocyte migration in a dose-dependent manner, with the (R)-enantiomer showing the more pronounced effect. To directly rule out the role of calcium channels in the antiatherosclerotic properties of lercanidipine, we examined the effect of the compounds on serum-stimulated calcium influx in SMC. Fluorimetry of Fluo 3 was used to measure changes in free cytosolic Ca2+ concentration ([Ca2+]i) in SMC after long-term preincubation (24 h) with the tested CA. Lercanidipine and its enantiomers (25 microM) decreased the serum-induced elevation of [Ca2+]i in SMC with the (S)-enantiomer (69% inhibition) 2.4-fold more active than the counterpart and the racemate (29% inhibition). In conclusion, our in vitro results suggest that lercanidipine may directly interfere with events involved in atherogenesis. The studies performed with enantiomers of lercanidipine suggest that the observed effects are not related to the blockade of voltage-dependent Ca2+ channels and confirm at least in vitro a pharmacologic potential of the compound to negatively influence the process of atherogenesis.

Animals↗
PubMed1996

KINFIT II: a nonlinear least-squares program for analysis of kinetic binding data.

We describe a versatile computer program for least-squares fitting of ligand/receptor association and dissociation curves from several experiments simultaneously. The program is designed to handle any number of classes of binding sites reacting with a single ligand that may have two forms: labeled and unlabeled. For a single class of binding sites, the exact, analytical solution is used to generate the computed curves. For more than one class of sites, the computed curves are generated through numerical solution of a set of ordinary differential equations. The parameters determined with this procedure are the on- and off-rate constants and the concentrations of each binding site class. An extensive selection of experimental designs can be processed. The times of observation may be freely chosen, although that choice will affect the quality of the results. Starting with a sample material (e.g., cells, membranes, macromolecules), one can preincubate (to equilibrium) with any combination of labeled and unlabeled ligand. One can then perturb the system by adding any combination of labeled and cold ligand or simply diluting the sample; such an experiment can be continued through several perturbations. A variety of such runs may be combined for analysis as a single data set.

Kinetics↗
PubMed1995

myc-immortalized microglial cells express a functional platelet-activating factor receptor.

The autacoid platelet-activating factor (PAF) takes part in a complex network of interactions regarding the cellular components of nervous tissues. Efforts aimed at characterizing the effects of PAF in the brain have been recently focalized on neurons because PAF exerts pleiotropic effects on these cells. Less attention has instead been paid to the glial component of the brain. We have used microglial cell lines immortalized from 13-day-old mouse embryo brains by a myc-transducing retrovirus. When exposed to physiological doses of PAF, immortalized microglial cells showed increases in intracellular free calcium concentrations due to release of calcium from internal stores, as well as to extracellular calcium influxes. These profiles of reactivity were independent from the immortalizing process, being observable in primary microglial cultures and in immortalized clones showing different proliferative rates. PAF was also able to induce transient expression of the c-fos protooncogene in serum-starved cultures and induced a strong chemotactic response in microglial cells. In contrast with control macrophage cultures, PAF did not promote prostaglandin or leukotriene synthesis in immortalized cells. This was most likely due to the low amount of total arachidonic acid found in immortal microglia, with respect to that observed in freshly isolated cells. Our data suggest that several of the effects observed after PAF stimulation might be independent from PAF-induced arachidonic acid metabolism. The availability of an in vitro microglial model might now help in studying the proinflammatory effects of PAF, both direct or microglia mediated, in the neural environment.

Animals↗
PubMed1995

Scoring acute spinal cord injury: a study of the utility and limitations of five different grading systems.

We recorded Frankel Scale, Yale Scale, Motor Index Score, Modified Barthel Index, Functional Independence Measurement scores, and important clinical parameters simultaneously and repetitively for 35 consecutive acute spinal cord injury patients. We found that 1) these scores can be determined as long as "yes/no" communication can be obtained reliably, pharmacological paralysis is not present, and a reliable observer with a flexible schedule is available, 2) impairment based scores (FS, YS, MIS) have little tendency to change during acute care, 3) function based scales (MBI, FIM) can be distorted by acute care phenomena which limit self care, 4) impairment-based and disability-based scales do not convert reliably, 5) none of these scales correlated strongly with common milestones for mobility or nutrition and 6) a good description of a population of ASCI patients can be made by a combination of two scales, one based on impairment and the other on disability.

Activities of Daily Living↗
PubMed1994

Thrombin generation in patients undergoing carotid endarterectomy: implications in acute vessel wall closure and antithrombotic therapy.

We determined the extent and duration of activation of coagulation during the first 24 hours after carotid endarterectomy. Serial blood samples were collected before, during and after surgery from 10 patients with severe stenosis (> 70%) undergoing carotid endarterectomy with heparinization. Platelet poor plasmas prepared from these samples, were analysed for activated prothrombin fragment F1 + 2 and thrombin-antithrombin III (TAT) levels, using commercially available ELISA kits. F1 + 2 and TATs were measured as indices of thrombin generation and inhibition respectively. Baseline F1 + 2 and TAT levels were 1.19 +/- 0.27 nMol/ml and 17 +/- 10 pMol/ml, respectively. Neither the F1 + 2 nor TAT level increased during surgery at a time when the patients were heparinized. However, both the F1 + 2 and TAT levels increased significantly within 3 hours after surgery and after the heparin had been neutralized with protamine, (p < 0.01). Moreover, both the F1 + 2 and TAT levels remained elevated in 75% of the patients for at least 24 hours, p < 0.01. We conclude that i) thrombin generation is significant post surgery in patients undergoing carotid endarterectomy despite their receiving heparin during surgery; ii) heparin may not be the ideal anticoagulant for carotid endarterectomy; and iii) persistent thrombin generation may contribute to early post-endarterectomy ischemic events.

Acute Disease↗
PubMed1994

Effects of loratadine on cytosolic Ca2+ levels and leukotriene release: novel mechanisms of action independent of the anti-histamine activity.

Loratadine, a non-sedating anti-histamine drug, displays in vitro potential anti-allergic properties not related to its interaction with the histamine H1 receptor. In a search for the mechanisms of these actions, we have found that loratadine induces an elevation of cytosolic calcium ion, [Ca2+]i, in rat peritoneal macrophages or human platelets. The mechanism of this elevation resides in the ability of loratadine to discharge intracellular Ca2+ stores, similarly to thapsigargin. This in turn brings about the inhibition of [Ca2+]i rise induced by physiological activators (platelet activating factor and ADP), as well as by thapsigargin. One of the active metabolites of loratadine, descarbo-ethoxy-loratadine, and another anti-histamine, namely terfenadine, exhibit the same effects. In addition, loratadine partially inhibits antigen-induced leukotriene release from human bronchi, but is unable to inhibit the concomitant contraction. We conclude that loratadine can interfere with the mechanisms controlling Ca2+ release, thus inhibiting the cell activation elicited by various agonists through [Ca2+]i elevation. This might be the mechanism underlying its anti-allergic actions in vitro. Furthermore, loratadine might represent an interesting tool in the study of Ca2+ homeostasis.

Animals↗
PubMed1994

Functional glucocorticoid receptor modulates pancreatic carcinoma growth through an autocrine loop.

Several peptide hormones have been shown to influence growth and function in pancreatic carcinoma and have given evidence for an autocrine feedback loop governing the proliferation of these malignant cells. Conversely, steroid hormones including glucocorticoids have been shown to inhibit the growth of pancreatic cancer cells; however, the prevalence of the glucocorticoid receptor or its mechanism of growth suppression in these tumors is unknown. The ability of growth factors thought to be active in this autocrine loop to reverse the glucocorticoid-induced growth inhibition was studied in vitro in a human pancreatic adenocarcinoma (HPAC) cell line with a well-characterized glucocorticoid receptor (GR). The glucocorticoid dexamethasone (DEX) inhibited growth in a dose-dependent manner as measured by a [3H]thymidine incorporation assay as well as an MTT cell proliferation assay. Maximal effects were seen within 48 hr at a concentration of 100 nM DEX, suppressing growth to approximately 18% of control. When the maximally suppressed DEX-treated cells were exposed to exogenous growth factors, they rapidly attained or exceeded the growth rate of control cells: insulin-like growth factor = 106%, transforming growth factor-alpha = 134%, insulin = 151%, and epidermal growth factor = 187% (all P < 0.05, Student's t test). In order to determine the frequency of the GR in pancreatic cancer and the clinical relevance of our findings, immunohistochemical staining for the GR was performed on 20 human tumors. Twelve (60%) of all cancers, as well as all normal pancreatic tissues (n = 4), stained positively for cytoplasmic and/or nuclear GR with expression correlating highly with degree of tumor differentiation (Kruskal-Wallis test, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoma↗
PubMed1994

Lower efficacy: interaction with an inhibitory receptor or partial agonism?

It is very common in practice to find that some concentration-response curves are 'bell shaped', and this phenomenon also applies to partial agonist curves. On the basis of these considerations, a mathematical model has been developed for the interaction of a ligand with two different receptors that mediate opposite effects (one stimulatory and one inhibitory), and is discussed in this article by Enrico Rovati and Simonetta Nicosia. This model can account for both an apparent reduction in efficacy and the curvature of the upper plateau of some concentration-response curves. Therefore, under certain conditions, an agonist that also interacts with an inhibitory receptor might be mistaken for a partial agonist, unless the concentration-response curves are performed over the widest possible range of concentrations.

Adenylyl Cyclases↗
PubMed1994

[Does aortic insufficiency influence Doppler-derived calculation of the valvular area in patients with mitral stenosis?].

BACKGROUND: The evaluation of mitral valve area (MVA) in patients with mitral stenosis represents the main purpose of any diagnostic method, provided that MVA is a key parameter to indicate the need for valve surgery. The aim of this study was to assess whether the presence of aortic regurgitation associated with mitral stenosis affects the MVA measurement by left atrial pressure half time (PHT). METHODS: Eighty-nine patients with mitral valve stenosis (68 females and 21 males, mean age 53.6 +/- 12.1 years), were studied. Fourty-eight patients (36 females and 12 males) had a concomitant aortic regurgitation (AR group), whereas 41 patients (32 females and 9 males) did not reflect any aortic valve involvement (no-AR group). Aortic regurgitation was graded on the basis of color flow analysis. The majority of patients had a slight to moderate regurgitation. MVA determination was carried out using both Hatle formula (220/PHT) and planimetric measurement in parasternal short axis view. RESULTS: Statistical analysis demonstrated a good correlation between the 2 MVA measurement in both groups (IA group: r = 0.9, p < 0.0001, SSE = 0.21 cm2, y = 0.91x + 0.05; no-IA group r = 0.92, p < 0.0001, SSE = 0.22 cm2, y = 0.92x + 0.04). The concomitant aortic valve disease did not affect in any way the MVA measurement by means of the PHT method. CONCLUSIONS: The Doppler derived method appears to be reliable for estimating the mitral valve area in patients with mitral stenosis even in the presence of aortic regurgitation.

Adult↗
PubMed1994

Stereochemical analysis and biological activity of 3-hydroxy-leukotriene B4: a metabolite from ethanol-treated rat hepatocytes.

Leukotriene B4 (LTB4), a biologically active metabolite derived from arachidonic acid by the 5-lipoxygenase cascade, is inactivated by cytochrome P-450-dependent omega-hydroxylation followed by second oxidation into a omega-carboxyl group. In many tissues, this second step is mediated by alcohol dehydrogenase. Isolated rat hepatocytes metabolized LTB4 in the presence of ethanol and ethoxyresorufin into substantial quantities of 3-hydroxy-LTB4 as determined by mass spectrometry. The absolute configuration of this metabolite was found to be greater than 98% 3(S)-hydroxy-LTB4 by comparison to synthetic standards. Investigation of the pharmacologic properties of the 3(S)- and 3(R)-hydroxy-LTB4 revealed that both caused a significant increase in intracellular free calcium in human neutrophils at 1 microM. Both enantiomers also induced thromboxane A2 release from the isolated guinea pig lung in a dose-dependent manner. This activity was fully blocked by a specific LTB4 receptor antagonist, LY223982, with an IC50 of 0.21 microM for LTB4. These results suggested that activation of the LTB4 receptor does not involve significant recognition of the carbon atoms close to the carboxyl moiety of LTB4. The failure of the hepatocyte to metabolically inactivate LTB4 in the presence of ethanol may be of importance to humans, particularly because the bioactive metabolite 3(S)-hydroxy-LTB4 was further metabolized by human neutrophils significantly more slowly than LTB4.

Animals↗