Cyclic DGR-peptidomimetic containing a bicyclic reverse turn inducer as a selective alpha(v)beta (5) integrin ligand.

3-Aza-6,8-dioxabicyclo[3.2.1]octane-based amino acids as reverse turn inducers have been introduced into cyclic peptidomimetics containing the RGD or DGR retro-sequence, in order to achieve a stereochemical scanning of the binding capability of the resulting molecules towards alpha(v)beta(3) and alpha(v)beta(5) integrins, resulting in retro-inverso DGR peptides as micromolar ligands. A comparative analysis between the conformational preferences of 4 and of its isomer 3, having the opposite RGD sequence, was reported with respect to the binding activity, giving insight into the factors affecting the preferential binding of 4 to the alpha(v)beta(5) integrin.

Time course of serum collagen types I and III metabolism products after reperfused acute myocardial infarction in patients with and without systemic hypertension.

We examined 55 consecutive patients successfully treated with primary percutaneous coronary intervention (PCI) for a first acute myocardial infarction with left ventricular (LV) systolic dysfunction. In all patients we performed echocardiographic examination, dosage of plasma brain natriuretic peptide, serum carboxy-terminal propeptide and telopeptide of procollagen type I and amino-terminal propeptide of procollagen type III at days 1 and 3, and at 1 and 6 months after index infarction. The hypertensive patients (group 1; n=30) differed for higher baseline blood pressure (133+/-4 mm Hg vs 118+/-4 mm Hg; P=0.03), greater LV mass index (108+/-5 vs 94+/-4 g m(-2), P=0.03) and lower mitral E/A wave peak (0.8+/-0.06 vs 1.1+/-0.12, P=0.02) with respect to non-hypertensive patients (group 2; n=25). From day 1 to month 6 carboxy-terminal propeptide of procollagen type I and amino-terminal propeptide of procollagen type III increased (P<0.005 and P<0.05, respectively) in both groups, whereas carboxy-terminal telopeptide of procollagen type I increased from day 1 to day 3 (P<0.01 in both groups, respectively) and then decreased from day 3 to month 6 (P<0.01 and P<0.05 in both groups, respectively). From day 1, brain natriuretic peptide decreased in both groups (P<0.005). There was no significant difference between the two groups in values of procollagens and natriuretic peptide. Finally, LV diastolic volume and function at 6 months were similar in the two groups. Thus, in patients with reperfused acute myocardial infarction and LV dysfunction, antecedent hypertension was not associated with a different pattern of serum procollagen release and ventricular remodelling at 6 months of follow-up.

Polydeoxyribonucleotides and nitric oxide release from guinea-pig hearts during ischaemia and reperfusion.

1. Two polydeoxyribonucleotides, produced by the controlled hydrolysis of DNA of mammalian lung (defibrotide and its lower molecular weight fraction, P.O. 085 DV), were studied for their ability to modify the release of nitrite and the coronary flow in perfusates collected from isolated, normally perfused hearts of guinea-pigs and from hearts subjected to regional ischaemia and reperfusion. 2. In guinea-pig normally perfused hearts, both defibrotide (DFT) and its fraction, P.O. 085 DV, increase the amount of nitrite appearing in perfusates in a concentration-dependent fashion. At the highest concentration studied (10(-6) M), P.O. 085 DV was more effective than DFT. A concomitant increase in the coronary flow was observed. 3. The increase in nitrite in perfusates and the increase in coronary flow induced by both DFT and P.O. 085 DV were significantly reduced by NG-monomethyl-L-arginine (L-NMMA, 10(-4) M), an inhibitor of nitric oxide synthase (NOS). 4. The endothelium-dependent vasodilator, acetylcholine (ACh), enhances the formation of nitrite and the coronary flow. Both the increase in coronary flow and in the formation of nitrite were significantly reduced by L-NMMA (10(-4) M). 5. In guinea-pig hearts subjected to ischaemia and reperfusion, the effect of both compounds in increasing the amount of nitrite in perfusates was more evident and more pronounced with P.O. 085 DV. 6. Reperfusion-induced arrhythmias were significantly reduced by both compounds to the extent of complete protection afforded by compound P.O. 085 DV. 7. The cardioprotective and antiarrhythmic effects of DFT and P.O. 085 DV are discussed.

Platelet Histamine: Characterization of the Proaggregatory Effect of Histamine in Human Platelets.

Minute amounts of histamine and a discrete histamine-forming capacity was present in quiescent human platelets. Aggregation of human platelets induced by thrombin was concomitant with the release of histamine. In platelets obtained from actively sensitized guinea pig, the exposure to the specific antigen results in aggregation and histamine release which was not reproduced by the exposure to an unspecific protein or in platelets taken from unsensitized animals. The present results lend further support to positioning platelets among the inflammatory cells.

First-pass cerebral extraction of benzamide-derivative radiotracers for SPECT.

Central dopaminergic receptors are widely studied for their importance in the pathophysiology of neurological and psychiatric diseases. We have investigated the cerebral delivery kinetics of three dopaminergic ligands in rats through the use of an indicator fractionation method to measure the tracer's regional influx rate constant with respect to regional blood flow. The aim is to collect the in vivo kinetic parameters of the radioligand cerebral distribution, which are necessary if, dealing with SPECT and "trapped" tracers, one wishes to analyse data using a graphical approach.

Generation of nitric oxide from nitrovasodilators modulates the release of histamine from mast cells.

The effect of organic and inorganic nitrovasodilators (sodium nitroprusside; 3-morpholinosydnonimine; glyceryl trinitrate; isosorbide dinitrate; sodium nitrite, was studied on the release of histamine evoked by compound 48/80 and calcium ionophore A 23187 in isolated purified rat serosal mast cells. All the compounds tested were capable of significantly reducing the release of histamine in a concentration-dependent fashion, at different levels of potency. This effect was reverted by oxyhaemoglobin. The inhibitory effect of glyceryl trinitrate on the release of histamine was potentiated in cells taken from animals pretreated with Escherichia coli lipopolysaccharide, and decreased by NG-nitro-L-arginine methyl ester. Glyceryl trinitrate and isosorbide dinitrate concentration-dependently increase the generation of nitric oxide by rat serosal mast cells. The inhibitory effect of glyceryl trinitrate and isosorbide dinitrate on the release of histamine from mast cells was potentiated by N-acetylcysteine, which significantly increases the generation of nitric oxide by mast cells. It is concluded that nitrovasodilators inhibit the release of mast cell histamine through the generation of nitric oxide. The effect may be relevant in considering the perivascular location of mast cells and the role played by these cells in cardiovascular pathophysiology.

Salmeterol inhibits anaphylactic histamine release from guinea-pig isolated mast cells.

Salmeterol (1 nM-100 microM) showed an inhibitory action on anaphylactic histamine release from mast cells, isolated from pleural and peritoneal cavities of actively sensitized guinea-pigs and stimulated by incubation with allergen. The effect is concentration-dependent and is reduced by the beta-adrenoceptor antagonist propranolol (1 microM). This study supports the hypothesis of an anti-inflammatory property of salmeterol, which concerns cells involved in the early phases of asthma.

[A syndrome caused by separating rags in textile industry: a new clinical entity?]. / La sindrome degli sfoderatori di stracci: una nuova entità clinica?

A group of 104 workers were examined. They were employed in selecting rags and separating the lining from wollen fabrics to be used again as thread waste in the textile industry. The aim of the study was to point out tendon and joint related disorders of the upper limb due to repetitive and forced movements. Twenty-eight (26.9%) workers complained of hand and wrist echography and thermography. In 19 patients (67.8%) clinical carpal tunnel syndrome was diagnosed. Eight workers (28.5%) had Dupuytren's contracture. Swelling of the fingers was found in 23 (82.1%). 14.2% and 28.5% of the workers showed respectively acro-osteolysis and acrosclerosis. The textile industry of Prato shows peculiar characters: the workers employed in selecting rags out a manual job which causes soft tissues and skeletal disorders in a great number of them. The acro-osteolytic and acrosclerotic changes of the fingers seem alike the bone disorders of chronic inflammatory rheumatic diseases as seronegative spondyloarthritis.

[Contribution of glutathione to detoxification in alcoholism. Biochemical-clinical studies]. / L'apporto di glutatione nella detossificazione dell'alcolismo. Indagini biochimico-cliniche.

The effects of reduced glutathione (GSH) administration (1.2 g/day and 2.4 g/day intravenously) on erythrocyte glutathione levels, serum gamma-glutamyl transpeptidase activity (GGTP) and urinary glucaric acid elimination were studied in a population of 24 chronic alcoholics voluntarily admitted to a 30 day detoxification protocol in comparison to a 12 patient control group treated only with chlordiazepoxide (initial dose 75-100 mg/day). Glutathione treatment increases dose-dependently and in a significant way erythrocyte glutathione levels and hastens the recovery of serum GGTP and urinary glucaric acid elimination. The relationship between glutathione, GGTP and glucaric acid is discussed, suggesting the possible role of GSH against the oxidative damage of alcohol.

False serum calcitonin high levels using a non-competitive two-site IRMA.

Dual site antibody-base immunoassays are commonly used in clinical laboratories to quantify the CT serum concentrations as a specific and sensitive marker of medullary thyroid carcinoma (MTC). Heterophile antibodies can interfere with these assays, however, and cause erroneous results. In order to avoid this interference, immobilized and conjugated antibodies from two different animal species or immunoreactive antibody fragments, as well as the addition of non-immune globulins, are generally included among the assay reagents. We describe the case of a 73-year-old man affected by a multinodular goiter, who showed high basal CT plasma levels as measured by a monoclonal antibody based IRMA. The finding of negative results for the presence of MTC at fine needle aspiration (FNA) and the mild increase observed in plasma CT during a pentagastrin (Pg) stimulation test, suggested that the high CT levels might depend on a cross-reaction with heterophilic antibodies. In fact, after the addition of the heterophilic blocking tube (HBT) to each specimen, the CT levels markedly decreased by more than 80% (average decrease+/-SE= 87.6+/-2.668%). Such a decrease strongly suggests that in our case the routinely used F(ab')2 fragments were unable to eliminate all of the interference and that the elevated serum CT levels might have been caused by human heterophilic antibodies. In conclusion, these results indicate a novel cause of CT false positivity, suggesting that high serum CT levels, when combined with a slight increase during Pg stimulation, should be critically interpreted in view of the possible presence of heterophilic antibodies in the specimens.

Definition of platelet-derived histamine-releasing factor and histaminergic receptors modulating platelet aggregation.

Endogenous and exogenous free radical scavengers significantly decrease mast cell histamine release induced by coincubation with resting, activated platelets or with platelet-derived supernatant. Histamine and pyridylethylamine dose-dependently enhance platelet aggregation; the effect is potentiated by ranitidine and blocked by mepyramine. Histamine increases also cytosolic calcium concentration in platelets stimulated with thrombin, and binding sites for [3H]-mepyramine are present on platelet membranes.

A place for free radicals in platelet-derived histamine releasing factor (PDHRF) and evidence that histaminergic receptors modulate platelet aggregation.

The release of histamine from rat serosal mast cells induced by coincubation with resting and activated human platelets, or by exposure of mast cells to supernatants obtained from activated platelets, is significantly reduced by anti-free radical interventions, and is coupled with the generation of membrane lipid peroxidation products. These results suggest free radical participation in the activity of PDHRF. Human platelets possess specific binding sites for an H1-receptor antagonist, suggesting that H1-receptors could modulate the intracellular calcium levels in a pro-aggregatory fashion.

Platelet aggregation and histamine release by immunological stimuli.

Platelet aggregation and histamine release were evaluated in normal and IgE pretreated human platelets exposed in vitro to IgE, anti-IgE and thrombin. The response of platelets from atopic donors directly stimulated with anti-IgE was also evaluated. Histamine release was measured by fluorimetric analysis of histamine content in platelets and in supernatants. The morphology of platelets exposed to immunological and non-immunological stimuli was recorded using an electron microscope. A detectable amount of histamine was measured in quiescent platelets. Their exposure to varying concentrations of thrombin produces a progressive aggregation which runs parallel to histamine release. The effects were significantly enhanced in platelets pretreated with IgE. Incubation of normal platelets with increasing concentrations of IgE myeloma protein, or with anti-human IgE antibody was ineffective on both aggregation and histamine release. However, incubation of platelets passively sensitized with IgE-myeloma protein with different concentrations of anti-human IgE antibody produces a concentration-dependent increase both in aggregation and histamine release. The same effects were obtained using platelets from atopic donors directly stimulated with anti-IgE. The electron microscopic pattern of platelet aggregation induced by thrombin was indistinguishable from that evoked by anti-IgE in IgE pretreated platelets. Loratadine, a non-sedative H1-receptor blocker, significantly abated platelet aggregation and histamine release induced by anti-IgE in IgE pretreated platelets.

Nitric oxide modulates cardiac and mast cell anaphylaxis.

Anaphylaxis in the isolated guinea-pig heart was associated with a sudden release of histamine with a long-lasting release of nitrite (NO2-), an oxidation product of NO. NG-monomethyl-L-arginine (MeArg, 300 microM) increased the severity of cardiac anaphylaxis, as shown by the decrease in the coronary flow and by a prolonged duration of antigen-induced arrhythmias. Concomitantly, MeArg increased the release of histamine while decreasing the release of nitrite. Sodium nitroprusside (NaNP, 10(-5)-10(-4) M) reduced the severity of cardiac anaphylaxis by increasing coronary flow and shortening the duration of antigen-induced arrhythmias. Concomitantly, NaNP decreased the release of histamine while increasing the release of nitrite. In mast cells isolated from actively sensitized guinea-pigs, the release of histamine elicited by specific antigen was increased by MeArg and decreased by NaNP. In conclusion, endogenous and exogenous NO antagonizes the effect of vasoconstrictor mediators released after antigen challenge and plays a protective role in anaphylactic reactions "in vitro".

Synthesis and preliminary biological characterization of a new potential (125)I-radioligand for dopamine and serotonin receptors.

The synthesis and a preliminary biological characterization of a new class of N-benzyl-aminoalcohols which have serotonin (5-HT(2)) and dopamine (D(2)) receptor affinity is described. In vitro competition binding studies were conducted with the new molecules and (3)H-spiperone on crude membrane preparation from rat striatum and frontal cortex. One of these compounds, 3-benzylamino-1-(4-fluoro-2-iodophenyl)-propan-1-ol (6f), whose IC(50) values are in the micromolar range for both the D(2) and 5-HT(2) receptors, was prepared in iodine-125 labelled form (6i) by nucleophilic substitution of the bromine atom of 3-benzylamino-1-(2-bromo-4-fluorophenyl)-propan-1-ol (6d). In the in vivo studies, conducted on rats, the radiolabelled molecule 6i shows a good capacity to cross the blood-brain barrier (BBB) with a mean value of first pass cerebral extraction (E) of ca. 50% when the regional cerebral blood flow, measured with microsphere technique, is in the experimental animal's physiologic range (0.8-1 mL/min/g). A preliminary in vitro autoradiographic distribution on coronal rat brain slices of the radioiodinated molecule showed that it was preferentially localized in the striatum and in the cerebral regions rich in dopamine- and serotonin receptors, even if a high non-specific binding was observed.

Histamine release from rat mast cells induced by the metabolic activation of drugs of abuse into free radicals.

BACKGROUND: The metabolic activation of morphine, cocaine and methadone into free radicals could have pathophysiological relevance in the organic injuries of drug addiction. METHODS: Isolated purified rat serosal mast cells were incubated with morphine, cocaine and methadone (10(-7) M-10(-4) M) with oxidative enzymes (prostaglandin-H-synthetase, 25 mU; rat liver homogenate fraction S 10-mix, 400 microl), and with the drugs of abuse in the presence of oxidative enzymes. Histamine and lactate dehydrogenase (LDH) were analysed with a fluorimetric and spectrophotometric assay, respectively; the generation of malonyldialdehyde (MDA) was measured by a spectrophotometric assay. RESULTS: The release of mast cell histamine and the generation of MDA are present only when mast cells were incubated with the drugs of abuse in the presence of oxidative enzymes. This release was dependent on the concentration of the drug in question and showed a maximum value at 10(-4) M. Moreover, in parallel experiments we demonstrated that, under the same experimental conditions, the release of LDH was always less than 20% of the total, suggesting that this effect is due to a selective exocytotic process. Histamine release and MDA generation were abated by the free radical scavengers: reduced glutathione, 10(-4) M GSH and alpha-tocopherol, 10(-4) M and by the spin trapper 5.5-dimethyl-1-pyrroline-N-oxide, 10(-4) M DMPO. The light and electron microscopic features are consistent with exocytotic secretion in the cases of morphine and methadone and with cell lysis in the case of cocaine. CONCLUSION: These results suggest that morphine, cocaine and methadone are activated into free radicals which produce membrane lipid perturbation and histamine release, suggesting that a massive release of mast cell histamine could be an additional risk factor in heroin and cocaine overdoses.

The role of histamine in platelet aggregation by physiological and immunological stimuli.

BACKGROUND: Platelets participate in allergic and inflammatory processes beside their role in haemostasis and thrombosis. This paper reports the level, the uptake, the metabolism and the release of histamine in human platelets. The effects of exogenous histamine, as well as the receptor and signal transduction of these effects, are also described. METHODS: Purified suspensions of platelets, prepared from healthy volunteers and from atopic patients, were exposed in vitro to physiological and immunological stimuli. Platelet aggregation was measured by the increase in light transmission; histamine content and release, as well as cytosolic free Ca2+ concentration, were measured fluorimetrically. Platelet histamine forming capacity, and the uptake of exogenous histamine, were measured with a radioisotopic method. RESULTS: Human platelets contain 72.5 +/- 9.6pmoles of histamine x 10(9) platelets, and their capacity to form histamine is 18.7 +/- 3.5pmoles h(-1)g(-1) protein, which is reduced by alpha-fluoromethylhistidine (10(-5) M) a selective inhibitor of the specific histidine decarboxylase. Human platelets take up the preformed amine by a calcium and energy-dependent process, and the uptake of histamine is reduced by mepyramine, an H1-receptor antagonist, and N,N-diethyl-2-[4-(phenylmethyl) phenoxyl] ethanamine (10(-6) M), a blocker of intracellular histamine receptors. Histamine is also metabolized by human platelets. The exposure of platelets to thrombin (10-60 mUml(-1)) produced a progressive aggregation, associated with histamine release. The same is observed in platelets isolated from atopic patients exposed to anti-IgE antibodies. Exogenous histamine dose-dependently potentiates the aggregation induced by physiological and immunological stimuli. In resting platelets cytosolic calcium level (207 +/- 4.2 nM/10(8) platelets) is increased by thrombin as well as by anti-IgE; this effect is potentiated by 10(-5) M histamine. CONCLUSIONS: The synergistic effect between histamine and other monoamines on platelet aggregation may explain some aspects of allergic vasculitis in which platelet aggregation is present.