Cutaneous mosaicism, in KRT1 pI479T patient, caused by the somatic loss of the wild-type allele, leads to the increase in local severity of the disease.

BACKGROUND: Epidermolytic ichthyosis (BCIE, OMIM 113800), is an autosomal dominant disorder of the skin caused by mutations in keratin genes KRT1 and KRT10. We present two sporadic patients showing a mild diffuse ichthyosis with palmoplantar keratoderma. Interestingly, one of them shows a significant hyperkeratosis of palms and soles similar to those present in the Meleda disease (OMIM 248300). OBJECTIVE: In this paper we would clarify the genetic difference between the two patients, giving rise to the different phenotype. METHODS: Clinical evaluation, followed by histological and molecular analysis has been established for these patients. RESULTS: We demonstrated the presence of a genetic cutaneous mosaicism. Both patients carry the KRT1 pI479T substitution, but in the palmoplantar areas of one of them, only the mutated allele is expressed (hemizygous). This leads to highlight a new type of cutaneous mosaic, the palmoplantar mosaicism.

Ischemic preconditioning prevents the impairment of hypoxic coronary vasodilatation caused by ischemia/reperfusion: role of adenosine A1/A3 and bradykinin B2 receptor activation.

We previously reported that hypoxic coronary vasodilatation (HCVD) is initiated by endothelial NO and sustained by adenosine. Prolonged ischemia/reperfusion impairs endothelium-dependent coronary vasodilatation, whereas transient ischemia (ie, preconditioning) protects the myocardium from subsequent ischemic events. Accordingly, we assessed whether prolonged ischemia/reperfusion impairs HCVD and whether preconditioning prevents this dysfunction. HCVD, elicited in isolated guinea pig hearts by a 1-minute exposure to 100% N2, consisted of an approximately 70% increase in coronary flow associated with enhanced nitrite/nitrate and adenosine overflow (+40% and 5-fold, respectively). After 30-minute global ischemia and 20-minute reperfusion, HCVD was decreased by approximately 60%, and the increases in nitrite/nitrate and adenosine overflow were abolished. Preconditioning (ie, three cycles of 5-minute global ischemia+5-minute reperfusion) prevented the impairment of HCVD and fully restored the increase in nitrite/nitrate overflow, but not that of adenosine. The protective effect of preconditioning was mimicked by perfusion with the adenosine A1 receptor agonist N6-cyclopentyladenosine and prevented by the A1 receptor antagonist N-0861. In addition, the A3 receptor agonist N6-(3-iodobenzyl)adenosine-5'-N-methyl-carboxamide had a similar protective effect. The bradykinin B2 receptor antagonist HOE 140 abolished the protective effect of preconditioning, whereas the NO synthase inhibitor N(omega)-methyl-L-arginine and the cycloxygenase inhibitor indomethacin did not. Our data indicate that preconditioning restores HCVD by a process that is triggered by activation of adenosine A1/A3 and bradykinin B2 receptors. The action of bradykinin is independent of NO and prostacyclin production. Once restored by preconditioning, HCVD is mediated by NO but no longer sustained by adenosine.

Three-dimensional spectral-spatial EPR imaging of free radicals in the heart: a technique for imaging tissue metabolism and oxygenation.

It has been hypothesized that free radical metabolism and oxygenation in living organs and tissues such as the heart may vary over the spatially defined tissue structure. In an effort to study these spatially defined differences, we have developed electron paramagnetic resonance imaging instrumentation enabling the performance of three-dimensional spectral-spatial images of free radicals infused into the heart and large vessels. Using this instrumentation, high-quality three-dimensional spectral-spatial images of isolated perfused rat hearts and rabbit aortas are obtained. In the isolated aorta, it is shown that spatially and spectrally accurate images of the vessel lumen and wall could be obtained in this living vascular tissue. In the isolated rat heart, imaging experiments were performed to determine the kinetics of radical clearance at different spatial locations within the heart during myocardial ischemia. The kinetic data show the existence of regional and transmural differences in myocardial free radical clearance. It is further demonstrated that EPR imaging can be used to noninvasively measure spatially localized oxygen concentrations in the heart. Thus, the technique of spectral-spatial EPR imaging is shown to be a powerful tool in providing spatial information regarding the free radical distribution, metabolism, and tissue oxygenation in living biological organs and tissues.

Histamine release by platelet aggregation.

Coincubation of rat serosal mast cells with human platelets leads to a significant release of histamine. which dose-dependently increases when platelet aggregation is induced by various concentrations of arachidonic acid. In turn, histamine enhances platelet aggregation induced by different agonists, this effect being mimicked by pyridyl-ethyl-amine (PEA), blocked by mepyramine and amplified by ranitidine. The data suggest the existence of a platelet-derived histamine releasing factor (PDHRF) and indicate the presence of platelet H1 and H2 receptors, capable of modulating platelet aggregation.

Histamine release from rat mast cells induced by metabolic activation of polyunsaturated fatty acids into free radicals.

Polyunsaturated fatty acids (PUFA: arachidonic and linoleic acid) release histamine from isolated purified rat serosal mast cells only in the presence of oxidizing systems such as phenobarbital-induced rat liver microsomes, prostaglandin-H-synthetase (PHS) or soybean lipoxygenase. The release of mast cell histamine by activated PUFA has a long time-course and the electron microscopical features are consistent with an exocytotic secretion in the case of arachidonic acid and cell lysis in the case of linoleic acid. The phenomenon is associated with a significant increase in malonyldialdehyde (MDA) and conjugated diene generation, suggesting a relationship between histamine release and membrane lipid peroxidation. The secretion of histamine was inhibited by anti-free radical interventions such as D-mannitol, reduced glutathione and alpha-tocopherol. Some cyclooxygenase and lipoxygenase inhibitors, cimetidine and carnitine derivatives, are differentially active in the inhibition of mast cell histamine release by activated arachidonic acid. These results suggest that free radical derivatives of PUFA, generated by metabolic activation, trigger mast cell histamine release.

The production of reactive oxygen species by dietary flavonols.

Flavonols are a group of naturally occurring compounds which are widely distributed in nature where they are found glycosylated primarily in vegetables and fruits. A number of studies have found both anti- and prooxidant effects for many of these compounds. The most widely studied because of their ubiquitous nature have been quercetin, a B-dihydroxylated and myricetin, a B-trihydroxylated flavonol. Some of their prooxidant properties have been attributed to the fact that they can undergo autooxidation when dissolved in aqueous buffer. Studying a number of factors affecting autooxidation, we found the rate of autooxidation for both quercetin and myricetin to be highly pH dependent with no autooxidation detected for quercetin at physiologic pH. Both the addition of iron for the two flavonols and the addition of iron followed by SOD for quercetin at physiologic pH. Both the addistantially. Neither kaempferol, a monohydroxylated flavonol nor rutin, a glycosylated quercetin showed any ability to autooxidize. The results with rutin differ from what we expected based on the B-ring structural similarity to quercetin. The autooxidation of quercetin and myricetin was further studied by electron spin resonance spectroscopy (ESR). Whereas quercetin produced a characteristic DMPO-OH radical, it was not detected below a pH of 9. However, the addition of iron allowed the signal to be detected at a pH as low as 8.0. On the other hand, myricetin autooxidation yielded a semiquinone signal which upon the addition of iron, converted to a DMPO-OH signal detected at a pH of 7.5. In a microsome-NADPH system, quercetin produced an increase in oxygen utilization and with ESR, an ethanol-derived radical signal which could be completely suppressed by catalase indicating the dependence of the signal on hydrogen peroxide. These studies demonstrate that the extracellular production of active oxygen species by dietary flavonols is not likely to occur in vivo but the potential for intracellular redox cycling may have toxicologic significance.

Vidian nerve resection, histamine turnover and mucosal mast cell function in patients with chronic hypertrophic non-allergic rhinitis.

Parasympathetic innervation of the respiratory tract of nasal mucosa plays an important role in the pathogenesis of chronic hypertrophic non-allergic rhinitis (C.H.N.A.R.), the vidian nerve providing the main parasympathetic nerve supply to respiratory mucosa. The present study investigates the effect of vidian nerve resection in 22 patient with intractable C.H.N.A.R. on histamine content and formation and on the number of mast cells and their degranulation in the respiratory tract. Samples were taken from respiratory mucosa for histamine and histidine-decarboxylase assay, and for microscopic observations for mast cell density and degranulation index, before and 12-24 months after vidian nerve resection. Neurectomy of the vidian nerve completely cured the clinical symptomatology, evaluated by rhinoreomanometry, and also significantly decreased both the high histamine levels and histidine-decarboxylase activity in patients with C.H.N.A.R. The density and degranulation index of mast cells were also significantly lower after surgery. These data suggest a relationship between cholinergic activity and the secretory response of mast cells and indicates a correlation between the parasympathetic nerve supply and chronic hyperthrophic non-allergic rhinitis. The significant reduction in mast cell density, histamine levels and histidine-decarboxylase activity also lends support to the hypothesis that the parasympathetic nerve supply plays a role in the regulation of mast cell histamine.

Ischemia-reperfusion injury and histamine release in isolated guinea-pig heart: the role of free radicals.

Free radicals produced by the occlusion and opening of the left anterior descending coronary artery and/or by perfusion of isolated guinea-pig heart with FeCl3/ADP (10 microM/100 microM) induce a differential release of histamine and lactate dehydrogenase (LDH) in the perfusates with a preferential liberation of histamine in the reperfusion phase, associated with an increase of ventricular arrhythmias. The release of histamine has been correlated with malonyldialdehyde (MDA) production and tissue calcium content in left ventricular tissue. MDA increased during ischemia, while the calcium content increased when the tissue was reperfused. Under these conditions, N-t-butyl-alpha-phenylnitrone (BPN), a molecule capable of forming spin adducts with free radicals, and D-mannitol are active in preventing reperfusion-induced arrhythmias.

Histamine release by free radicals: the relationship with the signal transduction system.

In isolated rat serosal mast cells exposed to free radical-generating systems, the release of histamine was associated with a significant increase in malonyldialdehyde (MDA) production suggesting a relationship between histamine release and membrane lipid peroxidation. Under these circumstances, an increase in cytosolic calcium was observed, uncoupled with any stimulation of inositol phospholipid (PtdIns) breakdown. The data suggest similarities between the release of histamine induced by calcium ionophores and by free radical-generating systems.

Free radicals induce ischemia-reperfusion injury and histamine release in the isolated guinea pig heart.

Free radicals are produced by perfusion of isolated guinea pig heart with FeCl3/ADP (10 microM/100 microM) and/or occlusion and opening of the left anterior descending coronary artery. Cardiac histopathology was correlated with histamine and lactate dehydrogenase release and with malondialdehyde production. A differential release of histamine and lactate dehydrogenase in the perfusate was detected, showing a preferential liberation of histamine in the reperfusion phase. The increase in lipid peroxidation product in left ventricular tissues after left coronary artery occlusion was maximal at the end of ischemia.

Prostaglandin H synthetase activates xenobiotics into free radicals: histamine release and biochemical characteristics.

In isolated rat serosal mast cells, studies with the fluorescent Ca2+ indicator, quin 2, and with [3H]-myoinositol to label endogenous polyphosphoinositides have established that an increase in cytosol Ca2+ levels was obligatory for histamine release by free radicals. No substantial breakdown of phosphatidylinositol and related polyphosphoinositides was associated with generation of the Ca2+ signal and histamine release, suggesting that the release of histamine by free radicals entails different pathways than the calcium-mobilizing receptors linked to polyphosphoinositides as second messengers.

Histamine release from nasal mucosal mast cells in patients with chronic hypertrophic non-allergic rhinitis, after parasympathetic nerve stimulation.

The vidian nerve provides the main parasympathetic nerve supply to nasal respiratory and maxillary sinus mucosa, and its electrical stimulation causes apparent secretory and vasodilatatory effects in animals. The present investigation was carried out in 8 patients with chronic hypertrophic non-allergic rhinitis (C.H.N.A.R.) undergoing therapeutic vidian nerve resection. The vidian nerve was electrically stimulated before the resection. Samples were taken from nasal sinus mucosa for histamine determination and microscopical observation before and after the stimulation period. Vidian nerve stimulation causes a significant decrease in histamine content and mast cell density in the mucosa sample, differentially influenced by eserine and atropine pretreatment.

Pathophysiological significance of the distribution of histamine receptor sub-types: a proposed dual role for histamine in inflammation and type I hypersensitivity reactions.

The pathophysiological significance of histaminergic receptors located on the membranes of immunocompetent cells is reviewed. H2-receptor agonists decrease the immunological histamine release from isolated serosal mast cells and from isolated hearts taken from actively sensitised guinea-pigs. Histamine and H2-receptor agonists inhibit the generation of superoxide anion from human neutrophils activated by FMLP and by substance P. These observations lend further support to the hypothesis of an immunodepression exerted by the activation of H2-receptors, which can be converted to immunostimulation by treatment with H2-receptor antagonists.

Modulation of anaphylactic histamine release by calcium channel agonists and antagonists.

Calcium antagonists have been reported to exert protective effects in hypersensitivity reactions in man and animals. However, their effect on anaphylactic histamine release is highly variable and controversial. In the present paper we evaluate the effect of calcium entry blockers and BAY K 8644 on the response to specific antigen in isolated hearts taken from actively sensitized guinea-pigs and from isolated rat and guinea-pig mast cells, actively or passively sensitized. Verapamil, diltiazem, nifedipine and prenylamine dose-dependently decreased anaphylactic histamine release in isolated actively sensitized guinea-pig mast cells. BAY K 8644 was found to be ineffective. In isolated, passively sensitized rat mast cells, verapamil showed a highly significant inhibitory effect, while prenylamine (10(-4) M) was able to evoke a histamine releasing effect. In cardiac anaphylaxis verapamil, diltiazem, prenylamine, but not nifedipine, were active in reducing the release of histamine without modifying the antigen-induced arrhythmias and positive chronotropic and inotropic effects.

Histamine release in acute coronary occlusion-reperfusion in isolated guinea-pig heart.

It has been shown that plasma histamine significantly increases during myocardial infarction in the dog. Histamine is also released when the isolated guinea-pig heart is reperfused after 30 minutes of low flow perfusion. The release of histamine and lactate dehydrogenase (LDH) after left anterior descending coronary artery ligation and release were investigated in the present study and related to the changes in electrocardiographic parameters and to a computer-aided analysis of left ventricular mast cell metachromasia. Spontaneous release of histamine was unchanged during ischemia and increased after the release of the ligature, while we observed a steady increase of LDH overflow. In parallel, a significant diminution of mast cell granule metachromasia was observed in left ventricular samples. The perfusion of the heart with FeCl3/ADP (10 microM/100 microM), a free radical-generating system, significantly enhanced both the basal and ischemic-reperfusion release of histamine, while perfusion with N-t-butyl-phenyl-nitrone (BPN/100 microM) a "spin-trapper" molecule, significantly decreased histamine and LDH release and the loss in metachromasia of left ventricular mast cells induced by reperfusion. Inhibitors of xanthine oxidase (allopurinol, 10 microM) and of calcium-activated proteases (leupeptin, 10 microM) modified the kinetics of histamine and LDH release.

Histamine release from serosal mast cells by intermediate products of arachidonic acid metabolism.

In the present paper we report the results of experiments carried out to measure the release of histamine from isolated rat mast cells during the metabolic activation of arachidonic acid. Arachidonic acid (10(-8)-10(-4) M) and the terminal products (10(-6) M) of the arachidonic acid pathways were devoid of any significant histamine releasing properties. A substantial amount of histamine was released from rat mast cells by low concentrations of arachidonic acid during incubation with prostanoid generating systems, such as guinea-pig lung microsomes, rat serosal macrophages and polymorphonuclear cells and prostaglandin-H-synthase from calf seminal vesicles. The release of histamine was not accompanied by a leakage of lactate dehydrogenase and was blocked by D-mannitol and by lipoxygenase and cyclooxygenase pathway inhibitors. The data are consistent with the hypothesis that free radical derivatives of arachidonic acid, originating from hydroperoxy fatty acids, are generated during catalysis, causing mast cell histamine release.

Histamine and lactate dehydrogenase (LDH) release in ischemic myocardium of the guinea-pig.

Histamine has been proved to be released during myocardial infarction and ischemic arrhythmias in dogs. The aim of the present experiments was to evaluate if ischemia and reperfusion modify histamine and lactate dehydrogenase (LDH) release in isolated guinea-pig heart. The results obtained show a steady increase of LDH release both in the ischemic and reperfusion phases. The release of histamine was reduced during the ischemic phase and increased significantly during reperfusion. A significant diminution of mast cell granule metachromasia was observed in the right auricles at the end of the reperfusion period. D-mannitol and reduced glutathione (GSH) modified the kinetics of histamine and LDH release. Cimetidine was able to decrease significantly the release of histamine during the ischemic and reperfusion phases and also reduced the release of LDH; triprolidine was completely ineffective. The results suggest that oxygen-derived free radicals may be involved in the pathogenesis of myocardial dysfunction after ischemia and reperfusion.

The antianaphylactic action of histamine H2-receptor agonists in the guinea-pig isolated heart.

The effects of histamine and of H1- and H2-receptor agonists on the response to specific antigen were studied in isolated hearts taken from actively sensitized guinea-pigs. Histamine and H2-receptor agonists (dimaprit, impromidine) dose-dependently decrease the positive chronotropic and inotropic effects, and the severity of arrhythmias evoked by the challenge of sensitized hearts with specific antigen. Nordimaprit and the selective H1-receptor agonist 2-pyridyl-ethyl-amine (2-PEA) did not modify the patterns of cardiac anaphylaxis. The positive inotropic and chronotropic responses of the isolated heart to exogenous histamine appear to be partly reduced in the presence of dimaprit. The H2-receptor agonists decrease the amount of histamine released during cardiac anaphylaxis which is increased by cimetidine, while nordimaprit and PEA were ineffective, indicating an inhibitory function afforded by H2-receptors in cardiac anaphylaxis.