Magnetic resonance imaging muscle lesions in presumptive canine fibrocartilaginous embolic myelopathy.

This retrospective cohort study reports the observation of magnetic resonance imaging (MRI) epaxial muscle hyperintensity in dogs diagnosed with presumptive fibrocartilaginous embolic myelopathy (FCEM) (n = 61). It further reports the observation of vertebral column hyperesthesia lasting > 12 hours. The hypothesis tested was that the finding of MRI epaxial muscle hyperintensity correlated with dogs presenting with hyperesthesia. Client-owned dogs diagnosed with presumptive FCEM by specific MRI criteria were included. Statistical analysis was performed using Fisher's exact test. Twenty-three percent (14/61) of MRIs displayed abnormal muscle hyperintensity and 43% (26/61) exhibited vertebral column hyperesthesia. No relationship was found between muscle hyperintensity and pain persisting beyond 12 hours. The muscle hyperintensity remains of unknown significance. That 43% of presumptive FCEM cases have prolonged signs of pain is a higher prevalence than previously reported, and may affect clinical differential diagnoses. This is especially significant in cases in which MRI is not possible and a presumptive diagnosis must be based on the clinical signs.

Imagerie par résonance magnétique des lésions des muscles dans la myélopathie embolique fibrocartilagineuse canine présumée. Cette étude rétrospective de cohorte signale les observations de l'imagerie par résonance magnétique (IRM) pour l'hyperintensité du muscle épaxial chez les chiens diagnostiqués avec une myélopathie embolique fibrocartilagineuse (MEFC) présumée (n = 61). Elle signale aussi l'observation de l'hyperesthésie de la colonne vertébrale durant > 12 heures. L'hypothèse qui a été testée était qu'il y avait une corrélation entre l'observation de l'hyperintensité du muscle épaxial par IRM et les chiens présentés avec de l'hyperesthésie. Les chiens appartenant à des clients pour lesquels un diagnostic présomptif de MEFC avait été posé à l'aide du critère spécifique de l'IRM ont été inclus. L'analyse statistique a été réalisée en utilisant le test exact de Fisher. Vingt-trois pour cent (14/61) des IRM affichaient une hyperintensité anormale du muscle et 43 % (26/61) présentaient de l'hypersthésie de la colonne vertébrale. Aucun lien n'a été trouvé entre l'hyperintensité musculaire et la douleur persistant au-delà de 12 heures. La signification de l'hyperintensité musculaire est toujours inconnue. Le taux de 43 % de cas présomptifs de MEFC affichant des signes de douleur prolongée représente une prévalence supérieure aux données déjà signalées et pourrait affecter les diagnostics cliniques différentiels. Ce fait revêt une importance particulière lorsque l'IRM n'est pas possible et qu'un diagnostic présomptif doit se baser sur les signes cliniques.(Traduit par Isabelle Vallières).

Juvenile cellulitis in a 7-week-old golden retriever dog.

A 7-week-old golden retriever puppy was presented with acute onset of marked facial inflammation and pustular dermatitis, markedly enlarged submandibular lymph nodes, and pyrexia. Treatment included high-dose corticosteroids and antibiotics. One week after presentation the puppy showed a significant decrease in inflammation and healing pustules.

Cellulite juvénile chez un chien Golden retriever âgé de 7 semaines. Un chiot Golden retriever âgé de 7 semaines a été présenté suite à l'apparition aiguë d'une inflammation faciale marquée et de dermatite pustuleuse, de ganglions lymphatiques sous-maxillaires significativement enflés et de pyrexie. Le traitement a inclus des fortes doses de corticostéroïdes et d'antibiotiques. Une semaine après la présentation, le chiot a manifesté une réduction significative de l'inflammation et des pustules en voie de guérison.(Traduit par Isabelle Vallières).

Structural investigation of protonated azidothymidine and protonated dimer.

Infrared multiple photon dissociation (IRMPD) spectroscopy experiments and quantum chemical calculations have been used to explore the possible structures of protonated azidothymidine and the corresponding protonated dimer. Many interesting differences between the protonated and neutral forms of azidothymidine were found, particularly associated with keto-enol tautomerization. Comparison of computational vibrational and the experimental IMRPD spectra show good agreement and give confidence that the dominant protonated species has been identified. The protonated dimer of azidothymidine exhibits three intramolecular hydrogen bonds. The IRMPD spectrum of the protonated dimer is consistent with the spectrum of the most stable computational structure. This work brings to light interesting keto-enol tautomerization and exocyclic hydrogen bonding involving azidothymidine and its protonated dimer. The fact that one dominant protonated species is observed in the gas phase, despite both the keto and enol structures being similar in energy, is proposed to be the direct result of the electrospray ionization process in which the dominant protonated dimer structure dissociates in the most energetically favorable way.

Consecutive fragmentation mechanisms of protonated ferulic acid probed by infrared multiple photon dissociation spectroscopy and electronic structure calculations.

Protonated ferulic acid and its principle fragment ion have been characterized using infrared multiple photon dissociation spectroscopy and electronic structure calculations at the B3LYP/6-311 + G(d,p) level of theory. Due to its extensively conjugated structure, protonated ferulic acid is observed to yield three stable fragment ions in IRMPD experiments. It is proposed that two parallel fragmentation pathways of protonated ferulic acid are being observed. The first pathway involves proton transfer, resulting in the loss of water and subsequently carbon monoxide, producing fragment ions m/z 177 and 149, respectively. Optimization of m/z 177 yields a species containing an acylium group, which is supported by a diagnostic peak in the IRMPD spectrum at 2168 cm(-1). The second pathway involves an alternate proton transfer leading to loss of methanol and rearrangement to a five-membered ring.

Tridentate ionic hydrogen-bonding interactions of the 5-fluorocytosine cationic dimer and other 5-fluorocytosine analogues characterized by IRMPD spectroscopy and electronic structure calculations.

Ionic hydrogen-bonding interactions have been found in several clusters formed by 5-fluorocytosine (5-FC). The chloride and trimethylammonium cluster ions, along with the cationic (proton-bound) dimer have been characterized by infrared multiple-photon dissociation (IRMPD) spectroscopy and electronic structure calculations performed at the B2PLYP/aug-cc-pVTZ//B3LYP/6-311+G(d,p) level of theory. IRMPD action spectra, in combination with calculated spectra and relative energetics, indicate that it is most probable that predominantly a single isomer exists in each experiment. For the 5-FC-trimethylammonium cluster specifically, the calculated spectrum of the lowest-energy isomer convincingly matches the experimental spectrum. Interestingly, the cationic dimer of 5-FC was found to have a single energetically relevant isomer (Cationic-IV) involving a tridentate ionic hydrogen-bonding interaction. The three sites of intermolecular ionic hydrogen bonds in this isomer interact very efficiently, leading to a significant calculated binding energy of 180 kJ/mol. The magnitude of the calculated binding energy for this species, in combination with the strong correlation between the simulated and IRMPD spectra, suggests that a tridentate-proton-bound dimer was observed predominantly in the experiments. Comparison of the calculated relative Gibbs free energies (298 K) for this species and several of the other isomers considered also supports the likelihood of the dominant protonated dimer existing as Cationic-IV.