170,059 research outputs found
Ossidazione di legami C-H catalizzata da complessi non-eme imminici del Ferro
No full textNonheme iron complexes are emerging as promising tools in the field of C-H bond activation. During the last decade several ligands have been synthesized and the catalytical activity of the corresponding iron complexes in aliphatic C-H oxidation was tested.[1] It was shown that ligand architecture have a great impact on catalyst’s activity and selectivity, with the more elaborated ligands usually performing better than the simple ones. However, this feature often leads to expensive and difficult to obtain ligands, thus hampering the diffusion of this synthetic methodology.[2]
In this context, we prepared a simple nonheme iron complex (3) assembled directly in the reaction vessel from cheap and commercially available reagents (Figure 1). Complex 3 is formed immediately and quantitatively and shows good activity in C-H bond oxidation, at least comparable to those reported in literature for other Fe(II) complexes, albeit with a simpler structure and at catalyst loading as low as 1%.[3]
The results of some hydrocarbon oxidations together with the full characterization of complex 3 will be presented. Some preliminary studies on the catalytic activity displayed by other imine-based nonheme iron complexes will be also disclosed.
[1] L. Que, Jr. and W. B. Tolman Nature, 2008, 455, 333-340.
[2] M. Cantà, D. Font, L. Gómez, X. Ribas, M. Costas Adv. Synth. Cat., 2014, 356, 818-830.
[3] G. Olivo, G. Arancio, L. Mandolini, O. Lanzalunga, S. Di Stefano, submitted
Ossidazione di legami C-H alifatici catalizzata da complessi non-eme imminici del Ferro
No full textMettere a punto un metodo di ossidazione di legami C-H non attivati al contempo efficiente e selettiva è una delle grandi sfide aperte nel campo della chimica organica. L’elevata stabilità dei legami C-H rende questa trasformazione chimica estremamente difficile. Nell’ultimo decennio, ispirandosi alla natura, numerosi gruppi di ricerca hanno sviluppato complessi non-eme del ferro quali modelli sintetici delle ossigenasi, riuscendo a mimare l’attività di tali enzimi nell’ossidazione di legami C-H non attivati in condizioni blande (temperatura ambiente, all’aria, con sali di ferro e H2O2 come ossidante). [1]
Dopo i primi promettenti risultati sono stati sintetizzati diversi complessi con attività catalitiche sempre più elevate. Per migliorare la selettività dell’ossidazione si è spesso fatto ricorso a leganti con strutture sempre più complesse con procedure sintetiche laboriose che limitano le potenzialità applicative di questi processi catalitici.[2]
Il nostro contributo allo stato dell’arte in questo settore di ricerca consiste nella preparazione di un ferro complesso (3) dalla struttura molto semplice, che si auto-assembla direttamente nell’ambiente di reazione a partire da reagenti commercialmente disponibili a basso costo: 2-piridincarbossaldeide 1, 2-picolilammina 2 e un sale di ferro (II) (Schema 1). Il complesso 3 è in grado di catalizzare l’ossidazione di una serie di idrocarburi con numeri di turnover elevati, paragonabili con quelli dei catalizzatori più efficienti preparati finora con bassi rapporti catalizzatore/substrato. [3]
Schema 1: Formazione del complesso 3.
Complessi imminici del ferro con diversa struttura sono in preparazione allo scopo di migliorare l’attività catalitica e la selettività nella ossidazione di idrocarburi e di altre classi di composti organici.
[1] Decker A., Rohde J.-U., Que L., Jr, Solomon E. I.; J. Am. Chem. Soc. 2004, 126, 5378-5379.
[2] Gòmez L., Garcia-Bosch I., Company A., Benet-Bucholz J., Polo A., Sala X., Ribas X., Costas M.; Angew. Chem. Int. Ed. 2009, 48, 5720-5723
[3] Olivo G., Arancio G., Mandolini L., Lanzalunga O., Di Stefano S., submitted
Growth hormone response to growth hormone-releasing hormone stimulation in obsessive-compulsive disorder
No full textTwo groups of 30 patients with obsessive-compulsive disorder and 30 age and sex-matched healthy control subjects were given a growth hormone-releasing hormone (GHRH) stimulation test to determine: (1) whether the downstream function of the somatotropic axis (growth hormone = GH, somatomedin-C = SMD-C) was impaired; (2) what might be the central alteration responsible for such impairment; and (3) whether alterations might be linked to the etiopathogenesis of the disease. Basal values of GH and SMD-C were the same in patients and control subjects, but GH responses to GHRH stimulation were significantly lower in patients than in control subjects. The absence of a pathology of basal GH and SMD-C concentrations indicates that the blunted GH responses to GHRH stimulation are not due to a negative feedback mechanism and suggests that a central neurotransmitter-neuropeptide pathology might be involved in the phenomenon. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved
C-H Bond Oxidation Catalysed by Nonheme Imine-based Fe(II) Complexes
No full textNonheme iron complexes are emerging as promising tools in the field of C-H bond activation, as they catalyze selective hydroxylation of non-activated C-H bonds using environmentally benign hydrogen peroxide as the terminal oxidant under mild conditions. During the last decade several ligands and the corresponding iron complexes have been prepared and tested as catalysts.1 It was shown that ligand properties are crucial for catalytic activity and reaction selectivity. The more sterically encumbered is the ligand, the more selective is the catalyst. However, this feature often leads to expensive and highly elaborated ligand structures, thus hampering the diffusion of this synthetic methodology.2
In this context, we prepared a simple nonheme iron complex (3) assembled directly in the reaction vessel from cheap and commercially available reagents (2-picolylamine 1, 2-picolinaldehyde 2 and an iron salt). Complex 3 is formed immediately and quantitatively in CH3CN solution and shows good activity in aliphatic C-H bond oxidation, comparable to those reported in literature for other Fe(II) complexes, albeit with a simpler structure and at low catalyst loading.3
The results of some hydrocarbon oxidations together with the full characterization of complex 3 will be presented. Some preliminary studies on the catalytic activity displayed by other imine-based nonheme iron complexes will be also disclosed.
(1) L. Que, Jr., W. B. Tolman, Nature 2008, 455, 333-340.
(2) Gòmez L., Garcia-Bosch I., Company A., Benet-Bucholz J., Polo A., Sala X., Ribas X., Costas M.; Angew. Chem. Int. Ed. 2009, 48, 5720-5723; Gorminsky P. E., White M. C.; J. Am. Chem. Soc. 2013, 135, 14052-14055; Cantà, M., Font D., Gòmez L., Ribas X., Costas M.; Adv. Synth. Cat. 2014, 356, 818-830.
(3) Olivo G., Arancio G., Mandolini L., Lanzalunga O., Di Stefano S., submitte
Dopamine function in obsessive-compulsive disorder: Growth hormone response to apomorphine stimulation
No full textIndirect observations suggest that the dopaminergic system may be involved in the pathophysiology of obsessive-compulsive disorder (OCD). The dopaminergic function of 15 patients with OCD and 15 age/sex-matched controls was evaluated by measuring the growth hormone (GH) responses to stimulation with the dopaminergic agonist apomorphine (APO), which increases growth hormone-releasing hormone (GHRH), GH, and somatomedine C (SMD-C) secretions, Therefore, we measured basal plasma GH and SMD-C concentrations and GH responses to GHRH stimulation to exclude that a downstream pathology of the somatotropic axis could obscure the significance of the results of the APO rest. The response of prolactin (PRL) to APO inhibition were also measured. Basal plasma levels of GH, SMD-C, and PRL, GH responses to GHRH stimulation and PRL responses to APO inhibition did not differ in the two groups of subjects. GH responses to APO stimulation were blunted in obsessive-compulsive (OC) patients. The emetic response to the same stimulation was stronger in patients than in controls. These responses suggest that in our OC patients there is a dysregulation of the dopaminergic system, which is possibly expressed in different ways in the various areas of the central nervous system. (C) 1997 Society of Biological Psychiatry
[Role of NGF in the development of primary sensory neurons in the rat]
No full textTwo populations of neurons are present in the dorsal root ganglia: i) the first which is connected with the neuromuscular spindles is localized in the mediodorsal (MD) part of the ganglion; ii) the second which is connected with the cutaneous receptors is localized in the ventrolateral (VL) part of the ganglion. The growth of MD but not of VL neurons in vitro is dependent upon the presence of the NGF. In order to study the presence in vivo of such differential effect of the NGF on the two neuronal populations, we have injected rat embryos with NGF antiserum (AS-NGF) and recorded the compound action potentials of different hindlimb nerves. We found that the sensory component, in the studied muscular nerves of the hindlimb, is seriously depressed in treated animals. These results indicate that the animals treated with AS-NGF suffer of a depression of activity in the afferents from the muscle spindles. This is probably due to a decrease in the number of these fibers in their muscle nerves
The 35% CO2 challenge test in patients with social phobia
No full textPanic disorder (PD) and social phobia (SP) share many clinical, demographic and biological characteristics. To investigate the relationships between the two disorders, the responses to inhalation of a 35% carbon-dioxide (CO2) and 65% oxygen (O-2) gas mixture were assessed. Sixteen patients with PD, 16 patients with SP, 13 patients with both SP and PD, seven patients with SP who experienced sporadic unexpected panic attacks and 16 healthy control subjects inhaled one vital capacity of 35% CO2 or compressed air. A double-blind, randomized, crossover design was used. PD patients and SP patients showed similar anxiogenic reactions to 35% CO2, both stronger than seen in control subjects. Patients with both disorders and SP patients with sporadic unexpected panic attacks reacted similarly to subjects with PD or SP alone. These results suggest that PD and SP share a common hypersensitivity to CO2 and thus might belong to the same spectrum of vulnerability. (C) 1997 Elsevier Science ireland Ltd
Panic attacks: A twin study
No full textThe role of genetic factors in panic disorder (PD) and sporadic panic attacks (SPAs) was investigated. A total of 120 twins recruited from the general population were interviewed for the presence of anxiety disorders and SPAs. A significantly higher concordance among MZ than DZ twins was found for PD (73% vs. 0%) but not for SPAs (57% vs. 43%). These results confirm a significant role of genetic factors in PD but suggest that genetic factors might not be crucial for the development of SPAs. (C) 1997 Elsevier Science Ireland Ltd
Central dopaminergic function in Anorexia and Bulimia Nervosa: a psychoneuroendocrine approach
No full textData on central dopamine (DA) function in patients with Anorexia Nervosa (AN) and Bulimia Nervosa (BN) are contradictory. To tentatively clarify the brain secretory state of the amine and its relationship with the nutritional impairments and/or the psychopathological aspects of the two disorders, we measured the responses of growth hormone (GH) to acute stimulation with apomorphine (APO), a selective D-1 and D-2 receptor agonist, in 16 AN patients, 8 restricted (AN-R) and 8 bingeing-purging (AN-BP), in 7 BN patients and in 8 healthy controls (CTR). Interference of impairment of the somatotropic axis in the GH response to APO stimulation was excluded by measuring the GH and insulin-like growth factor-1 (IGF-1) basal levels and GH responses to growth hormone-releasing hormone (GHRH) stimulation. Psychological aspects of patients and controls were investigated by the rating scales Eating Disorder Inventory (E.D.I.), Bulimic Investigation Test Edinburgh (B.I.T.E)., and Yale-Brown Cornell Eating Disorder Scale (YBC-ED). Basal GH levels were significantly higher and those of IGF-1 lower in AN-R than in AN-BP, BN and CTR subjects. GH responses to GHRH stimulation were significantly higher in AN-R than in AN-BP and BN patients and in CTR. GH responses to APO stimulation were significantly lower in AN-R and AN-BP than in BN and CTR subjects, suggesting that at the hypothalamic level there is a subsensitivity of postsynaptic D-2 receptors and possibly a presynaptic DA hypersecretion. The altered GH responses to APO stimulation did not correlate with the Body Mass Index, while they correlated negatively with E.D.I. scores. (C) 2001 Elsevier Science Ltd. All rights reserved. Z8 0 ZR 0 ZS 0 ZB 2
A ceRNA analysis on LMNA gene focusing on the Hutchinson-Gilford progeria syndrome
No full textBackground: Hutchinson-Gilford progeria syndrome is a rare dominant human disease of genetic origin. The
average life expectancy is about 20 years, patients’ life quality is still very poor and no efficient therapy has yet been
developed. It is caused by mutation of the LMNA gene, which results in accumulation in the nuclear membrane of
a particular splicing form of Lamin-A called progerin. The mechanism by which progerin perturbs cellular
homeostasis and leads to the symptoms is still under debate.
Micro-RNAs are able to negatively regulate transcription by coupling with the 3’ UnTranslated Region of messenger
RNAs. Several Micro-RNAs recognize the same 3’ UnTranslated Region and each Micro-RNA can recognize multiple
3’ UnTranslated Regions of different messenger RNAs. When different messenger RNAs are co-regulated via a similar
panel of micro-RNAs, these messengers are called Competing Endogenous RNAs, or ceRNAs.
The 3’ UnTranslated Region of the longest LMNA transcript was analysed looking for its ceRNAs. The aim of this
study was to search for candidate genes and gene ontology functions possibly influenced by LMNA mutations that
may exert a role in progeria development.
Results: 11 miRNAs were isolated as potential LMNA regulators. By computational analysis, the miRNAs pointed to
17 putative LMNA ceRNAs. Gene ontology analysis of isolated ceRNAs showed an enrichment in RNA interference
and control of cell cycle functions.
Conclusion: This study isolated novel genes and functions potentially involved in LMNA network of regulation that
could be involved in laminopathies such as the Hutchinson-Gilford progeria syndrom
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