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Splitting of molecular hydrogen (H2) into bridging and terminal hydrides is a common step in transition metal chemistry. Herein, we propose a novel organometallic platform for cleavage of multiple H2 molecules, which combines metal centers capable of stabilizing multiple oxidation states, and ligands bearing positioned pendant basic groups. Using quantum chemical modeling, we show that low-valent, early transition metal diniobium(ii) complexes with diphosphine ligands featuring pendant amines can favorably uptake up to 8 hydrogen atoms, and that the energetics are favored by the formation of intramolecular dihydrogen bonds. This result suggests new possible strategies for the development of hydrogen scavenger molecules that are able to perform reversible splitting of multiple H2 molecules.

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ABSTRACT Fascial defects with muscular herniation are an uncommon, treatable cause of calf pain. Differential diagnosis includes deep vein thrombosis, compartment syndrome, soleus strain/tear, and muscle or subcutaneous tumour. In this case, sonography was more sensitive for diagnosis than magnetic resonance imaging.

RESUMEN Los defectos fasciales con herniación muscular son una causa poco frecuente y tratable del dolor de pantorrilla. El diagnóstico diferencial incluye trombosis venosa profunda, síndrome compartimental, distensión o desgarro del sóleo, y tumor subcutáneo o muscular. En este caso, la sonografía resultó más sensible para el diagnóstico que la tomografía por resonancia magnética.

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ABSTRACT Objective: Shoulder pain, a common cause of productivity loss and health-related expense, is commonly due to rotator cuff tears. Magnetic resonance (MR) imaging with intra-articular gadolinium, MR arthrography, is accepted internationally as an excellent modality for evaluating the rotator cuff. Ultrasound is cheaper and only slightly less sensitive in detecting rotator cuff tears, but MR is superior in detecting ancillary lesions. Magnetic resonance arthrography was introduced at the University Hospital of the West Indies (UHWI), Jamaica, in July 2003. This study aimed to evaluate our experience with MR arthrography and assess its accuracy. Methods: A retrospective study was carried out. All MR arthrography cases performed at UHWI between July 2003 and July 2006 were reviewed. Medical records were reviewed to determine surgical correlation. Results: A total of 140 MR arthrograms were performed; 55% of the patients were female. Ages ranged from the second to the ninth decade, having a distribution approaching but not attaining a normal distribution (p = 0.03) with clustering in the middle years. Magnetic resonance arthrography demonstrated torn rotator cuffs in 40 patients, none of whom was under the age of 40 years (p < 0.001). Fifteen patients had surgery which confirmed torn rotator cuffs in all 15. Conclusion: Magnetic resonance arthrography was found to be accurate in detecting rotator cuff tears. It should be considered in the evaluation of patients with suspected rotator cuff tears. For patients under the age of 40 years, sonography could be used as an alternative.

RESUMEN Objetivo: El dolor en el hombro, el cual es causa común de pérdida de productividad y gastos relacionados con la salud, se debe comúnmente a desgarros del manguito rotador. La imagen por resonancia magnética (IRM) con gadolinio intra-articular - conocida como artrografía RM - se acepta internacionalmente como una excelente modalidad para evaluar el manguito rotador. El ultrasonido es más barato y sólo ligeramente menos sensible a la hora de detectar desgarros del manguito rotador, pero la RM es superior en la detección de lesiones secundarias. La artrografía por resonancia magnética se introdujo en el Hospital Universitario de West Indies (HUWI), Jamaica, en julio de 2003. Este estudio tuvo como objetivo evaluar nuestra experiencia con la artrografía RM y evaluar su precisión. Métodos: Se realizó un estudio retrospectivo. Se revisaron todos los casos de artrografías RM realizadas en HUWI entre julio de 2003 y julio de 2006. Se revisaron las historias clínicas a fin de determinar la correlación quirúrgica. Resultados: Un total de 140 artogramas RM fueron realizados. El 55% de los pacientes eran mujeres. Las edades variaron del segundo al noveno decenio, con una distribución que se acercaba pero no llevaba a alcanzar una distribución normal (p = 0.03), concentrándose en los años intermedios. La artrografía de resonancia magnética mostró desgarros de los manguitos rotadores en 40 pacientes, ninguno de los cuales tenía menos de 40 años (p < 0.001). Quince pacientes tuvieron cirugía que confirmaba desgarros de los manguitos rotadores en los 15. Conclusión: Se halló que la artrografía por resonancia magnética era exacta a la hora de detectar los desagarros del manguito rotador. Debe considerarse en la evaluación de pacientes con sospecha de desgarros del manguito rotador. Para los pacientes menores de 40 años de edad, la sonografía podría ser utilizada como alternativa.

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Behavioural responses of lemon sharks Negaprion brevirostris to a fin-mounted tag package (CEFAS G6A tri-axial accelerometer with epoxied Sonotronics PT4 acoustic transmitter) were measured in a controlled captive environment (n = 10, total length, LT range 80-140 cm) and in free-ranging sharks upon release (n = 7, LT range 100-160 cm). No changes were detected in behaviour (i.e. swimming speed, tailbeat frequency, time spent resting and frequency of chafing) between control and tagged captive shark trials, suggesting that the tag package itself does not alter behaviour. In the free-ranging trials, an initial period of elevated swimming activity was found in all individuals (represented by overall dynamic body acceleration). Negaprion brevirostris, however, appeared to recover quickly, returning to a steady swimming state between 2 and 35 min after release. Post-release tracking found that all sharks swim immediately for the shoreline and remain within 100 m of shore for prolonged periods. Hence, although N. brevirostris are capable of quick adaptation to stressors and demonstrate rapid recovery in terms of activity, tracking data suggest that they may modify their spatial use patterns post release. This research is important in separating deviation in behaviour due to environmental stressors from artefacts caused by experimental techniques.

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The authors present a case of a 42-year-old lady who visited her gynaecologist with dysuria and a sensation of incomplete voiding for 2 weeks. Urine culture grew Escherichia coli and blood studies were normal. Pelvic ultrasound revealed a smooth well-defined mass arising from the bladder wall. She was referred to the urologist who requested CT and MRI for further evaluation. These modalities confirmed an intramural bladder mass with normal overlying mucosa. The mass was deemed contributory to her symptoms and a decision was made to excise the mass surgically. Via a transurethral approach, cystoscopy revealed a smooth well-circumscribed intramural mass. This was partially excised. The mass was found to be a leiomyoma. Except for an uncomplicated urinary tract infection, her postoperative course has been uneventful.

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A CSF leak results from a defect in the dura and skull base. Due to the risk of potentially devastating central nervous system infection, it is an important entity. Timely diagnosis of CSF leaks is crucial. Laboratory testing of nasal or aural fluid drainage for the presence of the protein Beta(β)-2 transferrin plays a key role in establishing the presence of a CSF leak. Such assays are not always available, making imaging pivotal in the diagnosis of this entity. The development of minimally invasive endoscopic repair further underscores the importance of imaging as precise anatomic localization is important for repair. In this article, we review the literature and make suggestions for the appropriate radiological investigation ofpatients with suspected CSF leaks.

Las pérdidas de fluido cerebroespinal (FCE) son el resultado de un defecto en la dura y la base craneal. Debido a que tales pérdidas presentan el riesgo de infecciones capaces de devastar potencialmente el sistema nervioso central, las mismas constituyen una entidad importante. El diagnóstico a tiempo de pérdidas del FCE es crucial. Las pruebas de laboratorio realizadas al drenaje del fluido de la nariz y los oídos a fin de detectar la proteína Beta (β) 2 transferrina, desempeñan un papel clave a la hora de determinar la presencia de pérdida de FCE. Estos ensayos no se hallan siempre a disposición, con lo cual la imagen médica se hace fundamental para el diagnóstico de esta entidad. El desarrollo de reparaciones endoscópicas mínimamente invasivas subraya aún más la importancia de la imagen médica, por cuanto se requiere una localización anatómica precisa para realizar la reparación. En el presente artículo, se revisa la literatura y se hacen sugerencias a fin de lograr una investigación radiológica adecuada de los pacientes con sospecha de pérdida de FCE.

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A CSF leak results from a defect in the dura and skull base. Due to the risk of potentially devastating central nervous system infection, it is an important entity. Timely diagnosis of CSF leaks is crucial. Laboratory testing of nasal or aural fluid drainage for the presence of the protein Beta (beta)-2 transferrin plays a key role in establishing the presence of a CSF leak. Such assays are not always available, making imaging pivotal in the diagnosis of this entity. The development of minimally invasive endoscopic repair further underscores the importance of imaging as precise anatomic localization is important for repair In this article, we review the literature and make suggestions for the appropriate radiological investigation of patients with suspected CSF leaks.

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Chondro-epiphyseal separation of the distal humerus is a rare injury, and when it occurs in the newborn, it may be difficult to diagnose and is easily mistaken for a dislocation of the elbow. The unimpressive clinical appearance of such an injury of the elbow in an infant, as well as the absence of ossific nuclei of the distal humerus in the newborn, are responsible for the dilemma in making the diagnosis. Ultrasonography, a readily available, non-invasive technique, can be used to evaluate the non-ossified epiphysis about the elbow of infants to demonstrate dislocations, fractures, and physeal separations. Closed reduction with or without percutaneous Kirschner wire fixation is the treatment of choice for these injuries. In this article, we report on a case of complete epiphyseal separation in a neonate and discuss the problems arising in its diagnosis

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Chondro-epiphyseal separation of the distal humerus is a rare injury, and when it occurs in the newborn, it may be difficult to diagnose and is easily mistaken for a dislocation of the elbow. The unimpressive clinical appearance of such an injury of the elbow in an infant, as well as the absence of ossific nuclei of the distal humerus in the newborn, are responsible for the dilemma in making the diagnosis. Ultrasonography, a readily available, non-invasive technique, can be used to evaluate the non-ossified epiphysis about the elbow of infants to demonstrate dislocations, fractures, and physeal separations. Closed reduction with or without percutaneous Kirschner wire fixation is the treatment of choice for these injuries. In this article, we report on a case of complete epiphyseal separation in a neonate and discuss the problems arising in its diagnosis.

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