261 research outputs found
2-Substituted-3-acylindoles through the Palladium-Catalysed Carbonylative Cyclization of 2-Alkynyltrifluoroacetanilides with Aryl Halides and Vinyl Triflates
No full textThe palladium-catalysed reaction of readily accessible 2-alkynyltrifluoroacetanilides with aryl hanides and vinyl triflates under a carbon monoxide atmosphere (1 or 7 atm) the presence of potassium carbonate produce s 2-substituted-3-acyl indoles in fair to good yield. The acidity of the nitrogen-hydrogen bond proved to be of primary importance for the success of the reaction. The methodology has been applied to the synthesis of pravadoline, a drug that shows analgesic activity against postoperative pain in man
Biological and physico-chemical processes influence cutin and suberin biomarker distribution in two Mediterranean forest soil profiles
No full textRecent investigations have shown macromolecules, such as cutins, and suberins as effective markers for above and belowground plant tissues. These biopolyesters contain structural units specific for different litter components and for root biomass. The aim of this work was to understand the fate of plant organic matter (OM) in Mediterranean forest soils by evaluating the incorporation of cutin and suberin by measuring specific biomarkers. Soil and plant tissue (leaves, woods and roots) samples were collected in two mixed Mediterranean forests of Quercus ilex (holm oak) in costal stands in Tuscany (central Italy), which have different ecological and edaphic features. Ester-bound lipids of mineral and organic horizons and the overlying vegetation were analysed using the saponification method in order to depolymerise cutins and suberins and release their specific structural units. Cutin and suberin specific aliphatic monomers were identified and quantified by gas chromatographic techniques. The distribution of cutin and suberin specific monomers in plant tissue suggested that mid-chain hydroxy acids can be used as leaf-specific markers and α,ω-alkanedioic acids and ωC18:1 as root-specific markers. Differences in the distributions of biomarkers specific for above and belowground plant-derived OM was observed in the two types of soils, suggesting contrasted degradation, stabilisation and transport mechanisms that may be related to soil physico-chemical properties. The acidic and dry soil appeared to inhibit microbial activity, favouring stabilization of leaf-derived compounds, while, in the more fertile soil, protection within aggregates appeared to better preserve root-derived compounds. © 2011 Springer Science+Business Media B.V
Forest humus forms in Italy: a research approach
No full textThe environmental factors driving humus form differentiation in Italian forest soils were investigated for Moder, Mull and Amphi models, highlighting the high relative weight of tree species as a predictor. Specific soil-plant-litter- nutrient flow effects were evidenced, representing a direct influence of tree species on humus form development. The effect of parent material on pedofauna activity and composition appeared to be fundamental with key role played by calcium and phosphorus. Specific pathways leading to the evolution of Amphi, a major humus form in Italy, were discussed
Palladium-catalysed cyclization of 2-alkynylanilines to 2-substituted indoles under an acidic two-phase system
No full textThe cyclization of 2-alkynylanilines in the presence of PdCl2 and nBu4NCl under an acidic CH2Cl2-HCI two-phase system affords 2-substituted indoles in good to high yield, at room temperature. The reaction is particularly suited to the one-flask preparation of 2-substituted indoles from 2-ethynylaniline
Modulation of sarcoplasmic reticulum calcium channel by adenosine: a PKC-dependent pathway
No full textModulation of cardiac sarcoplasmic reticulum calcium release by adenosine: a protein kinase C-dependent pathway
No full textWe have already reported that A(3) adenosine receptor stimulation reduces [(3)H]-ryanodine binding and sarcoplasmic reticulum Ca(2+) release in rat heart. In the present work we have investigated the transduction pathway responsible for this effect. Isolated rat hearts were perfused for 20 min in the presence of the following substances: 100 nM N(6)-(iodobenzyl)-adenosine-5'-N-methyluronamide (IB-MECA), an A(3) adenosine agonist; 10 muM U-73122, a phospholipase C inhibitor; 2 muM chelerythrine, a protein kinase C inhibitor. At the end of perfusion, the hearts were homogenized and [(3)H]-ryanodine binding was assayed. IB-MECA produced a significant decrease in ryanodine binding, which was abolished in the presence of chelerythrine but not in the presence of U-73122. RT-PCR experiments showed that ryanodine receptor gene expression was not affected by IB-MECA. In Western blot experiments, ryanodine receptor phosphorylation on serine 2809 was not modified after perfusion with IB-MECA. We conclude that modulation of SR Ca(2+) release channel by IB-MECA is dependent on protein kinase C activation. However, in this model protein kinase C activation is not due to phospholipase C activation. In addition, changes in ryanodine receptor gene expression or direct phosphorylation of the ryanodine receptor on serine 2809 residue do not appear to occur
Palaeosols in an Upper Pliocene fluvial to shallow marine succession (Valdelsa Basin, Central Italy): A sequence-stratigraphic perspective
No full textThe present study provides an example of how palaeopedology and facies analysis may be integrated for the interpretation of a cyclothemic succession in the Upper Pliocene (Piacenzian) of the Valdelsa Basin (central Italy). The stacking of facies and intervening bounding surfaces, including palaeosols, outline a hierarchy of elementary (EDS) and composite (CDS) depositional sequences within the unconformity-bounded stratigraphic units (S4-S6 synthems) which compose the succession. The focus of the study is on synthem S4 and the transition to synthem S5. Synthem S4 records the development of a distal alluvial plain dominated by floodbasin mudstone with subordinated channelized sandstone (S41), followed by the incision of a fluvial valley aggraded by the cyclical stacking of braided and low sinuosity channelized conglomerate and sandstone (S42). Synthem S5 includes lower shoreface sandstone and inner shelf mudstone related to a major transgression which affected the study area during the late Piacenzian. Evidence of soil-forming processes is well preserved within sub-unit S41 where five palaeosols (PS4a-e) are stacked within the facies architecture of EDS1c-d, both being defined as transgressive to high stand tracts. Increasing palaeosol development was observed within both EDSs, while palaeosols were generally thicker and more closely stacked within EDS1d. Palaeosols were interpreted as marking minor cycles of accommodation space creation within EDS1c, while marking a better defined high stand tract in EDS1d. Increasing upward soil development was observed within each EDS, with generally better developed soils in EDS S41d. The unconformable transition from S4 to S5 is marked by a thin veneer of slope deposits, bearing pedogenic carbonates reworked from a missing PS4f palaeosol, formed during the shaping of the erosional surface separating sub-units S41 and S42. The results of this study indicate that: 1) the sedimentary and pedogenic processes recorded in the channelized facies and palaeosols in the floodbasin facies of sub-unit S41, are coherent with a palaeoenvironmental setting dominated by seasonal climate; 2) the facies-palaeosol architecture of S4 synthem corresponds to those described in sequence-stratigraphic models applied to continental successions. The pedo-sedimentary signature of the major sea-level fluctuation recorded in the transition between S4 and S5 synthem differs from these models. In this case a well-developed and drained palaeosol, expected to record the maximum regressive surface shaped during the falling stage of sea level, is missing. This difference is related to a rapid fall and subsequent rise of relative sea level which marked the transition between S4 and S5 synthems
Jet lag syndrome and circadian disorders of the sleep-wake cycle
No full textCircadian rhythm sleep disorders (CRSDs) are related to alterations in circadian timekeeping system or misalignment between endogenous circadian rhythm and exogenous factors, such as desidered or socially required time schedules, that affect sleep timing or duration. The most commonly observed are jet lag disorder, advanced and delayed sleep phase disorder, free-running disorder, and irregular sleep-wake disorder. The clinical picture may include sleep loss, fatigue, cognitive and vigilance deterioration and hormonal and gastrointestinal distress. Therapeutic management involves interventions aimed at mitigating symptoms affecting sleep and vigilance, and facilitating adaptation to the desired circadian schedule. Appropriately, scheduled bright and dim light exposure and melatonin administration are the main therapeutic tools together with sleep hygiene and chronotherapy. Excessive daytime sleepiness may benefit from short strategic naps and caffeine, whereas bedtime hypnotics may have favorable effect on sleep latency and maintenance. Melatonin and appropriately timed bright light exposure are effective in enhancing new time zone adaption, particularly for stays longer than 3-5 days, whereas short stopover may not benefit
Short-term effects of pressure overload on the expression of genes involved in calcium homeostasis
No full textWe investigated whether in the isolated perfused rat heart acute pressure overload may affect the expression of genes involved in calcium homeostasis, namely sarcolemmal L-type Ca2+ channel, Na+/Ca2+ exchanger, sarcoplasmic reticulum Ca2+-ATPase, phospholamban, and ryanodine receptor. Hearts were subjected to 210 min of perfusion under the following conditions: (i) standard working heart perfusion with preload and afterload set at 20 and 100 cm, respectively; (ii) working heart perfusion at high afterload (180 cm); (iii) retrograde infusion of St. Thomas' Hospital cardioplegic solution. In all models gene expression was determined by RT-PCR. Significant decrease in the expression of the sarcoplasmic reticulum Ca2+-ATPase gene was observed in the high afterload group. No significant change in the expression of any other gene was observed in any group. The reported effect was not detected after 60 min of perfusion, and it was blunted in the presence of the protein kinase C inhibitor chelerythrine, while the calcineurin inhibitor cyclosporin A was ineffective. In conclusion, the sarcoplasmic reticulum Ca2+-ATPase gene is downregulated after short-term (210 min) perfusion at high afterload, possibly through a protein kinase C-dependent pathway. This mechanism might play a relevant pathophysiological role in the response to pressure overload and in the development of hypertrophy
Microbial activity and organic matter composition in Mediterranean humus forms
No full textThe aim of this study was to characterise humus forms, intended as organic profile morphologies, and the associated soil chemical, biochemical (β-glucosidase, phosphatase and urease activities) and organic matter (SOM) properties in Mediterranean forest soils. Samples were collected from the organic layers (OF. +. OH) and the mineral topsoil (M01) in 31 Quercus spp. sites. To highlight the differences in soil organic matter (SOM) composition among humus forms, pyrolysis-gas chromatography (Py-GC) was used and the ratios of specific pyrolysis products were calculated. The main results achieved were that humus forms can be clearly separated according to enzyme activities and SOM pyrolytic fragments of the first mineral layer (M01). Humus forms showed a progression from mull macro, which was the richest in soil nutrients and with the highest enzyme activities, across amphi macro and amphi meso to an opposite end represented by mull meso and moder. This trend was also observed in the qualitative changes of SOM composition. In particular, the high ratios of pyrrole to phenol suggested that in macrostructured humus forms soil organic matter is more degraded, whereas high values of acetic acid and of the aliphatic to aromatic compounds ratio in moder and mull meso forms, indicate accumulation of fresh and biodegradable material. This study points to the high potential of humus forms as indicators of forest soil processes. © 2013 Elsevier B.V
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