101,939 research outputs found
Assessing the orbital contribution in the “spodium bond” by natural orbital for chemical valence–charge displacement analysis
No full textThe term "spodium bond"(SpB) has been recently proposed to describe the noncoordinative interaction that can be established between a polarized group 12 metal and a mild Lewis base (LB). Most of the systems showing short metal-donor distances compatible with SpB are characterized by the coexistence of multiple weak interactions, including hydrogen and halogen bonding, making the assessment of real importance of SpB difficult. Here, we show that the relative importance of each contribution can be probed by dissecting the orbital component of the interaction through the extended transition state-natural orbital for chemical valence-charge displacement analysis (ETS-NOCV-CD). The latter gives useful information about relative energies and electrons involved, for model systems ([(thiourea)2MX2]···LB; M = Zn, Cd, and Hg; X = Cl and I; and LB = CH2S, CH2O, CH3CN, and CO) and a variety of structures extracted from experimentally characterized adducts, allowing us to demonstrate the lack of a direct correlation between a favorable metal-base distance and the presence of an orbital contribution for the SpB
Adenosquamous carcinoma of the upper eyelid in a dog
No full textPurpose: To describe an adenosquamous carcinoma of the upper eyelid in a dog. Methods: A 12-year-old, male mongrel dog with a 6-month history of a progressive eyelid mass of the right upper eyelid was evaluated. Long-term bilateral topical application of 0.03% tacrolimus for third eyelid plasmoma and treatment cycles with systemic corticosteroids for a long-standing atopic dermatitis were reported by medical history. Complete physical and ophthalmologic examination of the dog as well as CBC, serum biochemical analysis, urinalysis, thoracic radiographs, and abdominal ultrasonography were performed. The mass was surgically removed and the eyelid was restored using a semicircular rotational flap from the periocular region. The removed mass was routinely processed, and 4 μm-thick sections were stained with haematoxylin and eosin. An additional immunohistochemistry with the streptavidin-biotin peroxidase method, using an anti-pan cytokeratin antibody, was also performed. Results: Clinical staging did not show any abnormality. Histological examination showed an invasive proliferation of malignant epithelial cells with intermixing of both adenocarcinomatous and malignant squamous cell components. A diagnosis of eyelid adenosquamous carcinoma was made. No evidence of local recurrence or distance metastases was identified during the 12-month follow-up period. Conclusions: To the authors’ knowledge, this is the first report on an adenosquamous carcinoma of the eyelid in the dog. Immunosuppression was found to be a significant clinical risk factor for cutaneous adenosquamous carcinoma in humans and it was considered a possible risk factor in this dog
Synthesis, Characterization, Interionic Structure, and Self-Aggregation Tendency of Zirconaaziridinium Salts Bearing Long Alkyl Chains
No full textZirconaaziridinium inner sphere ion pairs (ISIPs) bearing alkyl chains of different lengths, [Cp2Zr(eta(2)-(CH2NRR2)-R-1)(+)center dot center dot center dot X-] (R-1 = Me, R-2 = C2H5, X- = MeB(C6F5)(3)(-), (ZrBN)-B-NC2; R-1 = me, R-2 = C16H33, X- = MeB(C6F5)(3)(-), (ZrBN)-B-NC16; R-1 = R-2 = C18H37, X- = MeB(C6F5)(3)(-), (ZrBN)-B-NC18; R-1 = Me, R-2 = Ph, X- = MeB(C6F5)(3)(-), (ZrBN)-B-NPh; R-1 = R-2 = C18H37, X- = B(C6F5)(4)(-), (ZrBT)-B-NC18; R-1 = Me, R-2 = Ph, X- = B(C6F5)(4)(-), (ZrBT)-B-NPh), have been synthesized by the reaction of [Cp2ZrMe+center dot center dot center dot MeB(C6F5)(3)(-)] or [CP2ZrMe+center dot center dot center dot B(C6F5)(4)(-)] with the suitable tertiary amine followed by selective C-H activation of one Me group of the coordinated amine and methane elimination. Subsequent reaction of ISIPs with THF afforded the corresponding outer-sphere ion pairs (OSIPs) ([(ZrTHF)-T-NC2][BN], [(ZrTHF)-T-NC16][BN], [(ZrTHF)-T-NC18][BN], [(ZrTHF)-T-NPh][BN], [(ZrTHF)-T-NC18][BT], [(ZrTHF)-T-NPh][BT]) in which the anion has been displaced into the second coordination sphere. The interionic structure in solution (i.e., the relative cation-anion position) and the self-aggregation level of both ISIPs and OSIPs have been investigated by means of H-1 NOESY, F-19, H-1 HOESY, and diffusion PGSE NMR methods, in low polar solvents. It is found that, independent of the nature or length of the alkyl chains, the anion prefers to pair with the cation from the side of the nitrogen atom and THF in ISIPs and OSIPs, respectively. Self-aggregation of ion pairs into higher aggregates is also weakly influenced by the nature of the alkyl chains, but it is strictly connected with the nature of the counterion: ISIPs and OSIPs bearing B(C6F5)(4)(-) showed an increased tendency to form higher aggregates with respect to those containing MeB(C6F5)(3)(-). The level of the self-aggregation in benzene-d(6) and cyclohexane-d(12) has been quantified by fitting the hydrodynamic volumes obtained from NMR diffusion experiments with several models of indefinite self-association. The IK model, in which the equilibrium constants slightly increase on increasing the aggregation step, best describes the experimental trends in all cases. The standard Gibbs free energy of self-association at 297 K (Delta G(0)) for (ZrBN)-B-NC18 is -6.7 +/- 0.2 kJ mol(-1) and -12.6 +/- 0.7 kJ mol(-1) in benzene-d(6) and cyclohexane-d(12), respectively. In the same solvents, the values of Delta G(0) are -17.9 +/- 0.5 kJ mol(-1) and -25.0 +/- 0.3 kJ mol(-1) for [(ZrTHF)-T-NC18][BT]. At room temperature, 80% and 4% of [(ZrTHF)-T-NC18][BT]are present in the form of ion pairs in cyclohexane-d(12) at analytical concentrations of 10(-5) and 10(-3) M, respectively. The self-aggregation of [(ZrTHF)-T-NC18][BN] in cyclohexane-d(12) is strongly depressed by increasing the temperature
Night‐time symphony: lunar effects on the activity patterns of the wolf and its prey in a Mediterranean protected area
No full textEnvironmental drivers can influence animal behaviour, affecting movement patterns and spatial dynamics with a cascading effect. Furthermore, most species adapt their behaviour to ecological factors, such as predation risk. In human-dominated landscapes, most medium-to-large terrestrial mammals are crepuscular or nocturnal, limiting their opportunities for other temporal changes. However, the role of nocturnal illumination and the lunar cycle in these spatiotemporal patterns remains understudied. We used camera trapping data, kernel density estimation, and generalized additive models to analyse the effects of the lunar cycle and moonlight on activity patterns of wolves Canis lupus and their ungulate prey in a Mediterranean area, accounting for cloudiness and habitat. Our results give no support to spatial avoidance by prey, and wolves were spatially synchronized with them. Additionally, we found no evidence of changes in animal activity modulated by moon brightness. Instead, we identified more refined mechanisms driving the relationships between wolves and their prey. Specifically, wolves seemed to exploit darker nights in areas more frequently used by their main prey (i.e. wild boar Sus scrofa and fallow deer Dama dama). Wild boar were more active during the brightest nights in the sites most used by the predator, whereas fallow deer were more active in the sites used in an intermediate way by the wolf and during nights with a middle nocturnal light intensity. Roe deer Capreolus capreolus were slightly more active during darker nights and in more concealed sites. These outcomes suggest that animal activity patterns reflect a trade-off between species-specific physiological features (e.g. poor nocturnal visual acuity in wild boars), the need for foraging, prey availability, vigilance, predation risk, human disturbances, and ambient light levels. Our results contribute to shed light on the underexplored effects of lunar illumination on predator and prey activities and relationships, particularly in ecosystems experiencing the return of apex predators
Correlation Between Cyclo-oxygenase-2 and Vascular Endothelial Growth Factor Expression in Canine and Feline Squamous Cell Carcinomas
No full textOverexpression of cyclo-oxygenase (COX)-2 is involved in tumour growth and spread by modulating the production of angiogenic factors such as vascular endothelial growth factor (VEGF). Expression of COX-2 and VEGF was investigated immunohistochemically in 51 canine and feline cutaneous and non-cutaneous squamous cell carcinomas (SCCs) and the correlation between expression of these molecules and clinicopathological variables was evaluated. COX-2 and VEGF expression was not observed in normal skin keratinocytes. COX-2 overexpression occurred in 53% and 61% of the canine and feline SCCs, respectively. The expression of both markers was higher in cutaneous compared with non-cutaneous SCCs. In both species COX-2 and VEGF expression was correlated with the progression of the disease, but not with the presence of lymphatic invasion, tumour grading or tumour classification in the cutaneous tumours. Further study will be required to understand the role of the COX-2 pathway in angiogenesis in SCC
Probing the association of frustrated phosphine-borane Lewis pairs in solution by NMR spectroscopy
No full text19F,1H HOESY, diffusion, and temperature-dependent 19F and 1H NMR studies allowed us to unequivocally probe the association between the frustrated PR3/B(C6F 5)3 (1, R = CMe3; 2, R = 2,4,6-Me 3C6H2) Lewis pairs in aromatic solvents. No preferential orientation is favored, as deduced by combining 19F,1H HOESY and DFT results, suggesting association via weak dispersion rather than residual acid/base interactions. The association process is slightly endoergonic [K = 0.5 M-1, ΔG 0(298 K) = +0.4 kcal/mol for 2], as derived from diffusion NMR measurements. © 2013 American Chemical Society
An NMR study on the reaction of substituted dimethyl zirconocenes with dimethylanilinium borate
No full textThe reaction of a series of dimethyl zirconocenes [Me2Si(Cp)2ZrMe2, 1; Cpt−bu2ZrMe2, 2; Cpn−bu2ZrMe2, 3; Ind2ZrMe2, 4; CpMe42ZrMe2, 5; Cp∗2ZrMe2, 6] with [HNMe2Ph][B(C6F5)4] was investigated by means of NMR spectroscopy. It was found that protonolysis of a Zr–Me group occurred generating a coordinative vacancy at the metal center and methane. Cations coming from 1–4 dimethyl precursors bound NMe2Ph, liberated from the protonation process, and formed zirconaaziridinium ion pairs {[Me2Si(Cp)2Zr(η2–CH2NMePh)][B(C6F5)4], 7; [Cpt−bu2Zr(η2–CH2NMePh)][B(C6F5)4], 8; [Cpn−bu2Zr(η2–CH2NMePh)][B(C6F5)4], 9; [Ind2Zr(η2–CH2NMePh)][B(C6F5)4], 10}, reasonably as a consequence of CH activation of one Me group of coordinated NMe2Ph and methane elimination. The intramolecular/interionic structures and dynamics of 7–10 ion pairs were investigated by 1H, 13C and 19F 1D-and 2D-NMR techniques. The reactions of 7 and 10 ion pairs with 2-methyl-1-heptene afforded stable diastereoisomeric ion pairs bearing a five-member azametallacycle
Neospora caninum oocyst shedding in a naturally infected dog from Italy
No full textAlthough the seroprevalence of Neospora caninum infection in dogs can be relatively high, there are few reports of dogs naturally shedding N. caninum oocysts. Worldwide, the prevalence of Neospora excretion in canine faeces ranges from 0.03% to 4.9%. A mixed-breed male household dog of about 8 years in age living in the district of Pisa (Tuscany, Central Italy) was referred for dysorexia, weakness and general lymph node enlargement. Clinical pathology demonstrated mild normocytic and normochromic anemia, thrombocytopenia and hypoproteinemia with hypoalbuminemia. Serology for Leishmania, Ehrlichia canis and Anaplasma phagocytophilum was negative. From lymph node and bone marrow analysis, T cell lymphoma, high grade, pleomorphic type, clinical stage V, was diagnosed. The dog was treated with a chemotherapy induction protocol with vincristine, cyclophosphamide, and prednisone for 8 weeks. A faecal sample collected from the dog 7 days after the beginning of the treatment and analysed by flotation test and a McMaster method, revealed the presence of 300 OPG N. caninum-like unsporulated oocysts of about 10–11 μm in diameter. An aliquot of the same faecal sample analysed by PCR with species-specific primer pairs Np6 +/Np21 + was positive for N. caninum DNA, while specific serology performed on sera collected at the first visit and a month later by IFAT, were positive with a titer of 1: 50 and 1:400, respectively. Soon after the dog died. Naturally occurring systemic illness or iatrogenic immunosuppression may predispose dogs to proliferation of the parasite. The dog was receiving chemo-immunosuppressive treatment for T cell lymphoma. For this reason it is possible to suppose that emission of Neospora oocysts in this dog was caused by reactivation of a latent infection
Low-temperature kinetic NMR studies on the insertion of a single olefin molecule into a Zr-C bond: Assessing the counterion-solvent interplay
No full textSticky counterions: Low-temperature kinetic NMR studies were performed to determine ΔH ≠ and ΔS ≠ values for the insertion of a single 2-methyl-1-heptene molecule into a Zr-C bond of [Cp 2Zr(η 2-CH 2NMePh)][X] (1a: X -=MeB(C 6F 5) 3 -, 1b: B(C 6F 5) 4 -) in [D 8]toluene and a 1:1 mixture of [D 8]toluene and [D 5]chlorobenzene. Both activation parameters critically depend on the interplay of the counterion and the solvent. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Multicentric molecular and pathologic study on canine adenovirus type 1 in red foxes (Vulpes vulpes) in three European countries
No full textCanine adenovirus type 1 (CAdV-1) is the agent of infectious canine hepatitis, a severe frequently fatal disease affecting primarily dogs (Canis lupus familiaris). The virus has been detected in many wild carnivore species. Our aim was to evaluate the prevalence and genetic and histopathologic features of CAdV-1 in wild red foxes (Vulpes vulpes). Kidney and liver samples were obtained from 86 subjects, coming from the UK (n¼21), Italy (n¼36), and Germany (n¼29). We used PCR, targeting the viral E3 gene and flanked regions, to detect the presence of the virus; viral E3, fiber, and E4 genes were sequenced and their sequences were compared with published sequences. Kidneys and liver from foxes in Italy and Great Britain (n¼57) were prepared for histologic and immunohistochemical examination for CAdV-1. Viral DNA was detected in 22% (19 of 86) kidney samples, with E3 and E4 genes showing reported and unreported single nucleotide changes. No pathologic changes or viral immunopositive signals were detected in the examined tissues. Our study suggests that red foxes could be considered potential shedders of CAdV-1, as they showed a relatively high prevalence without related pathologic changes in the organs examined
- …
