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1.
Glob Chang Biol ; 27(11): 2537-2548, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33694271

RESUMEN

Climate-mediated species redistributions are causing novel interactions and leading to profound regime shifts globally. For species that expand their distribution in response to warming, survival depends not only on their physiological capacity, but also on the ability to coexist or be competitive within the established community. In temperate marine reefs from around the world, the range expansion of tropical species, known as 'tropicalization', has been linked to the disappearance of temperate habitat-forming kelps and shifts to dominance by low-biomass turfing algae. The consequences of these range expansions and habitat changes on resident fish communities are, however, unclear. Here, we use data derived from baited remote underwater video (BRUV) surveys to analyse changes in diversity and abundance of marine fishes over a 17-year period in warming reefs that have experienced kelp loss (occurring c. 2009). Despite the loss of kelp, we found that species richness and overall abundance of fishes (measured as probability of occurrence and relative abundance), including both tropical and temperate species, increased through time. We also found dramatic shifts in the trophic composition of fish assemblages. Tropical herbivorous fish increased most markedly through time, and temperate-associated planktivores were the only group that declined, a potential consequence of tropicalization not previously identified. At the species level, we identified 22 tropical and temperate species from four trophic guilds that significantly increased in occurrence, while only three species (all temperate associated) declined. Morphological trait space models suggest increases in fish diversity and overall occurrence are unlikely to be driven by uniqueness of traits among tropical range expanders. Our results show more winners than losers and suggest that pathways of energy flow will change in tropicalized systems, as planktonic inputs become less important and a higher proportion of algal productivity gets consumed locally by increasingly abundant herbivores.


Asunto(s)
Kelp , Animales , Biomasa , Arrecifes de Coral , Ecosistema , Peces , Herbivoria
2.
Crit Care ; 20: 100, 2016 Apr 12.
Artículo en Inglés | MEDLINE | ID: mdl-27072503

RESUMEN

BACKGROUND: Severe trauma continues to represent a global public health issue and mortality and morbidity in trauma patients remains substantial. A number of initiatives have aimed to provide guidance on the management of trauma patients. This document focuses on the management of major bleeding and coagulopathy following trauma and encourages adaptation of the guiding principles to each local situation and implementation within each institution. METHODS: The pan-European, multidisciplinary Task Force for Advanced Bleeding Care in Trauma was founded in 2004 and included representatives of six relevant European professional societies. The group used a structured, evidence-based consensus approach to address scientific queries that served as the basis for each recommendation and supporting rationale. Expert opinion and current clinical practice were also considered, particularly in areas in which randomised clinical trials have not or cannot be performed. Existing recommendations were reconsidered and revised based on new scientific evidence and observed shifts in clinical practice; new recommendations were formulated to reflect current clinical concerns and areas in which new research data have been generated. This guideline represents the fourth edition of a document first published in 2007 and updated in 2010 and 2013. RESULTS: The guideline now recommends that patients be transferred directly to an appropriate trauma treatment centre and encourages use of a restricted volume replacement strategy during initial resuscitation. Best-practice use of blood products during further resuscitation continues to evolve and should be guided by a goal-directed strategy. The identification and management of patients pre-treated with anticoagulant agents continues to pose a real challenge, despite accumulating experience and awareness. The present guideline should be viewed as an educational aid to improve and standardise the care of the bleeding trauma patients across Europe and beyond. This document may also serve as a basis for local implementation. Furthermore, local quality and safety management systems need to be established to specifically assess key measures of bleeding control and outcome. CONCLUSIONS: A multidisciplinary approach and adherence to evidence-based guidance are key to improving patient outcomes. The implementation of locally adapted treatment algorithms should strive to achieve measureable improvements in patient outcome.


Asunto(s)
Trastornos de la Coagulación Sanguínea/terapia , Manejo de la Enfermedad , Tratamiento de Urgencia/métodos , Guías como Asunto , Hemorragia , Europa (Continente) , Medicina Basada en la Evidencia/métodos , Hemorragia/terapia , Humanos , Heridas y Lesiones/complicaciones , Heridas y Lesiones/terapia
3.
J Am Chem Soc ; 137(17): 5730-40, 2015 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-25871450

RESUMEN

Hydrogen bonds profoundly influence the architecture and activity of biological macromolecules. Deep appreciation of hydrogen bond contributions to biomolecular function thus requires a detailed understanding of hydrogen bond structure and energetics and the relationship between these properties. Hydrogen bond formation energies (ΔGf) are enormously more favorable in aprotic solvents than in water, and two classes of contributing factors have been proposed to explain this energetic difference, focusing respectively on the isolated and hydrogen-bonded species: (I) water stabilizes the dissociated donor and acceptor groups much better than aprotic solvents, thereby reducing the driving force for hydrogen bond formation; and (II) water lengthens hydrogen bonds compared to aprotic environments, thereby decreasing the potential energy within the hydrogen bond. Each model has been proposed to provide a dominant contribution to ΔGf, but incisive tests that distinguish the importance of these contributions are lacking. Here we directly test the structural basis of model II. Neutron crystallography, NMR spectroscopy, and quantum mechanical calculations demonstrate that O-H···O hydrogen bonds in crystals, chloroform, acetone, and water have nearly identical lengths and very similar potential energy surfaces despite ΔGf differences >8 kcal/mol across these solvents. These results rule out a substantial contribution from solvent-dependent differences in hydrogen bond structure and potential energy after association (model II) and thus support the conclusion that differences in hydrogen bond ΔGf are predominantly determined by solvent interactions with the dissociated groups (model I). These findings advance our understanding of universal hydrogen-bonding interactions and have important implications for biology and engineering.


Asunto(s)
Agua/química , Enlace de Hidrógeno , Espectroscopía de Resonancia Magnética , Estructura Molecular , Teoría Cuántica , Solventes/química , Termodinámica
4.
Artículo en Alemán | MEDLINE | ID: mdl-24563397

RESUMEN

The electroencephalogram (EEG) of wakefulness, sleep, and anaesthesia changes during childhood. Especially marked are the changes during the first year of life. In the second half of the first year, in most children EEG stages can be classified visually and automatically during anaesthesia which are similar to those observed in older children. In the first months of life, the EEG of anaesthesia is less differentiated, but it is still useful in patient monitoring during anaesthesia.


Asunto(s)
Anestesia/métodos , Monitoreo Intraoperatorio/métodos , Sueño/fisiología , Adolescente , Envejecimiento/fisiología , Niño , Preescolar , Monitores de Conciencia , Electroencefalografía/efectos de los fármacos , Humanos , Lactante , Recién Nacido , Vigilia
5.
Crit Care ; 17(2): R76, 2013 Apr 19.
Artículo en Inglés | MEDLINE | ID: mdl-23601765

RESUMEN

INTRODUCTION: Evidence-based recommendations are needed to guide the acute management of the bleeding trauma patient. When these recommendations are implemented patient outcomes may be improved. METHODS: The multidisciplinary Task Force for Advanced Bleeding Care in Trauma was formed in 2005 with the aim of developing a guideline for the management of bleeding following severe injury. This document represents an updated version of the guideline published by the group in 2007 and updated in 2010. Recommendations were formulated using a nominal group process, the Grading of Recommendations Assessment, Development and Evaluation (GRADE) hierarchy of evidence and based on a systematic review of published literature. RESULTS: Key changes encompassed in this version of the guideline include new recommendations on the appropriate use of vasopressors and inotropic agents, and reflect an awareness of the growing number of patients in the population at large treated with antiplatelet agents and/or oral anticoagulants. The current guideline also includes recommendations and a discussion of thromboprophylactic strategies for all patients following traumatic injury. The most significant addition is a new section that discusses the need for every institution to develop, implement and adhere to an evidence-based clinical protocol to manage traumatically injured patients. The remaining recommendations have been re-evaluated and graded based on literature published since the last edition of the guideline. Consideration was also given to changes in clinical practice that have taken place during this time period as a result of both new evidence and changes in the general availability of relevant agents and technologies. CONCLUSIONS: A comprehensive, multidisciplinary approach to trauma care and mechanisms with which to ensure that established protocols are consistently implemented will ensure a uniform and high standard of care across Europe and beyond.


Asunto(s)
Trastornos de la Coagulación Sanguínea/terapia , Manejo de la Enfermedad , Hemorragia/terapia , Traumatismo Múltiple/terapia , Guías de Práctica Clínica como Asunto/normas , Trastornos de la Coagulación Sanguínea/diagnóstico , Trastornos de la Coagulación Sanguínea/epidemiología , Monitoreo de Drogas/métodos , Monitoreo de Drogas/normas , Europa (Continente)/epidemiología , Hemorragia/diagnóstico , Hemorragia/epidemiología , Humanos , Traumatismo Múltiple/diagnóstico , Traumatismo Múltiple/epidemiología , Ensayos Clínicos Controlados Aleatorios como Asunto/métodos , Ensayos Clínicos Controlados Aleatorios como Asunto/normas
6.
Crit Care ; 17(2): 136, 2013 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-23635083

RESUMEN

According to the World Health Organization, traumatic injuries worldwide are responsible for over 5 million deaths annually. Post-traumatic bleeding caused by traumatic injury-associated coagulopathy is the leading cause of potentially preventable death among trauma patients. Despite these facts, awareness of this problem is insufficient and treatment options are often unclear. The STOP the Bleeding Campaign therefore aims to increase awareness of the phenomenon of post-traumatic coagulopathy and its appropriate management by publishing European guidelines for the management of the bleeding trauma patient, by promoting and monitoring the implementation of these guidelines and by preparing promotional and educational material, organising activities and developing health quality management tools. The campaign aims to reduce the number of patients who die within 24 hours after arrival in the hospital due to exsanguination by a minimum of 20% within the next 5 years.


Asunto(s)
Concienciación , Promoción de la Salud/métodos , Hemorragia/terapia , Hemostasis/fisiología , Trastornos de la Coagulación Sanguínea/diagnóstico , Trastornos de la Coagulación Sanguínea/epidemiología , Trastornos de la Coagulación Sanguínea/terapia , Exsanguinación/diagnóstico , Exsanguinación/epidemiología , Exsanguinación/terapia , Promoción de la Salud/tendencias , Hemorragia/diagnóstico , Hemorragia/epidemiología , Mortalidad Hospitalaria/tendencias , Humanos
7.
Inorg Chem ; 51(13): 7025-31, 2012 Jul 02.
Artículo en Inglés | MEDLINE | ID: mdl-22694272

RESUMEN

Terminal oxo complexes of the late transition metals Pt, Pd, and Au have been reported by us in Science and Journal of the American Chemical Society. Despite thoroughness in characterizing these complexes (multiple independent structural methods and up to 17 analytical methods in one case), we have continued to study these structures. Initial work on these systems was motivated by structural data from X-ray crystallography and neutron diffraction and (17)O and (31)P NMR signatures which all indicated differences from all previously published compounds. With significant new data, we now revisit these studies. New X-ray crystal structures of previously reported complexes K(14)[P(2)W(19)O(69)(OH(2))] and "K(10)Na(3)[Pd(IV)(O)(OH)WO(OH(2))(PW(9)O(34))(2)]" and a closer examination of these structures are provided. Also presented are the (17)O NMR spectrum of an (17)O-enriched sample of [PW(11)O(39)](7-) and a careful combined (31)P NMR-titration study of the previously reported "K(7)H(2)[Au(O)(OH(2))P(2)W(20)O(70)(OH(2))(2)]." These and considerable other data collectively indicate that previously assigned terminal Pt-oxo and Au-oxo complexes are in fact cocrystals of the all-tungsten structural analogues with noble metal cations, while the Pd-oxo complex is a disordered Pd(II)-substituted polyoxometalate. The neutron diffraction data have been re-analyzed, and new refinements are fully consistent with the all-tungsten formulations of the Pt-oxo and Au-oxo polyoxometalate species.

8.
Arch Orthop Trauma Surg ; 132(9): 1363-70, 2012 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-22660797

RESUMEN

INTRODUCTION: The aim of our study was to investigate in vitro and in a new in vivo rat model for impaired bone healing whether a low dose BMP-2 preparation in fibrin would be equivalent or better than the combination of collagen and a high dose of BMP-2 which is currently in clinical use. MATERIALS AND METHODS: In a 14 day period we compared the in vitro release kinetics of an absorbable collagen sponge (ACS) with 72 µg rhBMP-2 in the BMPC group and fibrin matrix with 10 µg rhBMP-2 in the BMPF group. In our in vivo experiment a critical sized osteotomy was performed in the rat femur, which was filled with a spacer, inhibiting bone formation for a period of 4 weeks. In a second operation this spacer was removed and the test item was applied into the defect. We compared the BMPF and BMPC groups with the ACS alone, FIBRIN alone and the EMPTY (4w/8w) control groups. 4 and 8 weeks after the second operation, specimens were analysed by X-ray and µCT imaging. Mechanically stable femurs were biomechanically evaluated. RESULTS: Cumulative BMP-2 release was five times higher in the BMPF group than in the BMPC group during the observation period. µCT analysis revealed that both the extent of bone union and the bone volume were significantly higher in the group with a lower dose of BMP-2 in fibrin matrix than in the groups without BMP-2 treatment. However there was no statistically significant difference between the BMPF and BMPC groups. CONCLUSION: We conclude that fibrin matrix is an excellent carrier for BMP-2 and that it provides equivalent results with a sevenfold lower dose of BMP-2 compared with ACS.


Asunto(s)
Proteína Morfogenética Ósea 2/farmacología , Regeneración Ósea/efectos de los fármacos , Colágeno/farmacología , Fibrina/farmacología , Factor de Crecimiento Transformador beta/farmacología , Animales , Fenómenos Biomecánicos , Modelos Animales de Enfermedad , Matriz Extracelular , Fémur/efectos de los fármacos , Fémur/fisiopatología , Técnicas In Vitro , Masculino , Osteotomía , Ratas , Ratas Sprague-Dawley , Proteínas Recombinantes/farmacología
9.
J Am Chem Soc ; 132(26): 8998-9006, 2010 Jul 07.
Artículo en Inglés | MEDLINE | ID: mdl-20552958

RESUMEN

The cubic intermetallic phase Y(4)Mn(1-x)Ga(12-y)Ge(y) (x = 0-0.26, y = 0-4.0) has been isolated from a molten gallium flux reaction. It presents a rare example of a system where ferromagnetism can be induced by controlling the vacancies of the magnetic centers. The Y(4)PdGa(12) type crystal structure is made up of a corner-sharing octahedral network of Ga and Ge atoms with Mn atoms at the centers of half the octahedra and Y atoms in the voids. At the highest Ge concentration, y = 4.0, the Mn site is nearly fully occupied, x = 0.05, and the samples are paramagnetic. At a lower Ge concentration, y = 1.0, Mn deficiency develops with x = 0.10. Surprisingly, strong ferromagnetism is observed with T(c) = 223 K. When Ge is excluded, y = 0, Mn is substantially deficient at x = 0.26 and ferromagnetism is maintained with a T(c) of approximately 160 K. In addition, a 6-fold modulated superstructure appears owing to an ordered slab-like segregation of Mn atoms and vacancies. Corresponding bond distortions propagate throughout the octahedral Ga network. Structure-property relationships are examined with X-ray and neutron diffraction, magnetic susceptibility, and electrical resistivity measurements.

10.
Crit Care ; 14(2): R52, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-20370902

RESUMEN

INTRODUCTION: Evidence-based recommendations are needed to guide the acute management of the bleeding trauma patient, which when implemented may improve patient outcomes. METHODS: The multidisciplinary Task Force for Advanced Bleeding Care in Trauma was formed in 2005 with the aim of developing a guideline for the management of bleeding following severe injury. This document presents an updated version of the guideline published by the group in 2007. Recommendations were formulated using a nominal group process, the Grading of Recommendations Assessment, Development and Evaluation (GRADE) hierarchy of evidence and based on a systematic review of published literature. RESULTS: Key changes encompassed in this version of the guideline include new recommendations on coagulation support and monitoring and the appropriate use of local haemostatic measures, tourniquets, calcium and desmopressin in the bleeding trauma patient. The remaining recommendations have been reevaluated and graded based on literature published since the last edition of the guideline. Consideration was also given to changes in clinical practice that have taken place during this time period as a result of both new evidence and changes in the general availability of relevant agents and technologies. CONCLUSIONS: This guideline provides an evidence-based multidisciplinary approach to the management of critically injured bleeding trauma patients.


Asunto(s)
Fluidoterapia , Técnicas Hemostáticas , Choque Hemorrágico/terapia , Heridas y Lesiones/complicaciones , Tratamiento de Urgencia , Europa (Continente) , Medicina Basada en la Evidencia , Humanos , Choque Hemorrágico/diagnóstico , Índices de Gravedad del Trauma , Heridas y Lesiones/terapia
11.
J Trauma ; 66(4): 1140-5, 2009 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-19359927

RESUMEN

BACKGROUND: Interlocking nailing is a standard procedure in the surgical treatment of tibial fractures. Despite it has been described to be a safe technique with excellent functional results compared with conservative treatment, a common problem is the development of anterior knee pain. The anatomic relation of Hoffa's fat pad with its nociceptors to the nail entry point has not been investigated, yet. METHODS: Eighteen formalin-fixed lower cadaver extremities of 11 cadavers (five females, six males) were matched into three groups: three approaches (medial paratendinous, transligamentous, and lateral paratendinous) were performed and the anterosuperior tibial cortex was opened with a cheese cutter. To investigate the relationship of the nail entry point and Hoffa's fat pad, the joint capsule was incised, and Hoffa's fat pad was exposed and then dissected carefully. Damage to the fat pad was recorded as well as meniscal lesions, cartilage lesions, and ligamentous lesions. After full extension and flexion of the knee joint, the motion of Hoffa's fat pad (millimeter) was recorded with a measuring gauge. The zone for safe nail insertion (millimeter square) without any lesion to intra-articular structures was recorded. RESULTS: Violation of Hoffa's fat pad was recorded if the lateral and transligamentous approach were used. With the medial approach, no damage of the fat pad was recorded. Total mean lateralization of the fat pad from extension to flexion over 90 degrees was 18.5 mm compared with its location in the fully extended knee. The safe zone for nail insertion without violation of menisci, cartilage, or ligaments was a triangle in the posteromedial aspect of the Hoffa with a mean dimension of 19.4 mm2. CONCLUSION: On the basis of our results, we can recommend the nail insertion via a medial paratendinous surgical approach to avoid injuries to the Hoffa fat pad and to menisci, cartilage, and ligaments.


Asunto(s)
Tejido Adiposo/anatomía & histología , Clavos Ortopédicos , Fijación de Fractura/métodos , Articulación de la Rodilla/anatomía & histología , Fracturas de la Tibia/cirugía , Tejido Adiposo/lesiones , Diseño de Equipo , Femenino , Humanos , Masculino
12.
Arch Orthop Trauma Surg ; 129(2): 207-19, 2009 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-19009303

RESUMEN

INTRODUCTION: Both fractures of the lumbar spine and at the thoracolumbar junction are quite common. The treatment of these fracture types is discussed controversially. Some authors advocate surgical treatment even in fractures without neurologic compromise while other series report good results after non-operative treatment. MATERIALS AND METHODS: Between January 1997 and April 2004, 324 patients with spinal fractures were admitted to our institution. Hundred and thirty-six patients with compression and burst type fractures treated by closed reduction and casting were available for follow-up. Their medical records, radiographs and computer tomography scans were reviewed and their functional status was assessed. RESULTS: 94 male (69.1%) and 42 female (30.9%) patients with a mean age of 48.6 years (range 17-81) at time of injury were included. The thoracolumbar junction (T11-L1) was affected in 104 patients (76.5%). 23.5% had lumbar fractures. All of the burst type fractures with involvement of the posterior column affection were type A3.3. fractures according to the Magerl classification. Significant correction of radiographic parameters was achieved in the early postreduction period (P < 0.0001). Reduction could not be maintained at the final follow-up but still showed slight improvement compared to the initial presentation. Reduction could be maintained better in the thoracolumbar region than in the lumbar spine. Neurologic function was restored in all patients with unilateral radicular pain but only one patient recovered fully after cauda equina-syndrome. Patients after lumbar spine indicated a higher level of pain when compared to patients with fractures at the thoracolumbar junction. DISCUSSION: Closed reduction and casting is a safe and effective method for treatment of compression and burst type fractures at the thoracolumbar junction and can restore neurologic function in patients with unilateral radicular pain. It is of limited value in lumbar fractures and in burst type fractures with posterior column involvement.


Asunto(s)
Moldes Quirúrgicos , Fijación de Fractura/métodos , Vértebras Lumbares , Fracturas de la Columna Vertebral/terapia , Vértebras Torácicas , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Radiografía , Estudios Retrospectivos , Fracturas de la Columna Vertebral/diagnóstico por imagen , Adulto Joven
13.
Biomed Tech (Berl) ; 54(2): 76-82, 2009 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-19290850

RESUMEN

Gender-related differences in the pharmacology of drugs used in anaesthesiology have been reported by different authors. The aim of this study was to compare propofol dosages in a greater number of male and female patients who had received electroencephalogram (EEG) monitoring to maintain a defined depth of anaesthesia. Data from an EEG-controlled study were analysed with regard to gender differences in the consumption of the short-acting hypnotic propofol during maintenance of total intravenous anaesthesia and with regard to recovery times. The 656 patients (239 male, 417 female) were 15 to 97 years old, underwent different surgical procedures, and received propofol in combination with remifentanil, a short-acting opioid. During the steady-state of anaesthesia the EEG stage D(2)/E(0), which corresponds to deep hypnosis, was the target level (EEG monitor: Narcotrend). Propofol dosages were calculated as mg/kg body weight/h and as mg/kg lean body mass/h. Significantly higher propofol dosages were observed in female patients compared to male patients, especially with lean body mass as a reference parameter. The dosages were characterised by a high interindividual variability. The time from stop of propofol until extubation was significantly shorter in women than in men. The propofol dosage for maintenance of anaesthesia at the EEG level D(2)/E(0) decreased with increasing age.


Asunto(s)
Anestésicos Intravenosos/administración & dosificación , Encéfalo/efectos de los fármacos , Encéfalo/fisiología , Electroencefalografía/efectos de los fármacos , Propofol/administración & dosificación , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Relación Dosis-Respuesta a Droga , Femenino , Humanos , Inyecciones Intravenosas , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Factores Sexuales , Adulto Joven
14.
J Am Chem Soc ; 130(10): 3127-36, 2008 Mar 12.
Artículo en Inglés | MEDLINE | ID: mdl-18271587

RESUMEN

The characterization of a new five-coordinate derivative of (2-methylimidazole)(tetraphenylporphinato)iron(II) provides new and unique information about the effects of forming a hydrogen bond to the coordinated imidazole on the geometric and electronic structure of iron in these species. The complex studied has two crystallographically distinct iron sites; one site has an axial imidazole ligand modified by an external hydrogen bond, and the other site has an axial imidazole ligand with no external interactions. The iron atoms at the two sites have distinct geometric features, as revealed in their molecular structures, and distinct electronic structures, as shown by Mössbauer spectroscopy, although both are high spin (S = 2). The molecule with the external hydrogen bond has longer equatorial Fe-N(p) bonds, a larger displacement of the iron atom out of the porphyrin plane, and a shorter axial bond compared to its counterpart with no hydrogen bonding. The Mössbauer features are distinct for the two sites, with differing quadrupole splitting and isomer shift values and probably differing signs for the quadrupole splitting as shown by variable-temperature measurements in applied magnetic field. These features are consistent with a significant change in the nature of the doubly populated d orbital and are all in the direction of the dichotomy displayed by related imidazole and imidazolate species where deprotonation leads to major differences. The results points out the possible effects of strong hydrogen bonding in heme proteins.


Asunto(s)
Compuestos Ferrosos/química , Metaloporfirinas/química , Cristalografía por Rayos X , Electrones , Compuestos Ferrosos/síntesis química , Enlace de Hidrógeno , Metaloporfirinas/síntesis química , Modelos Moleculares , Conformación Molecular , Temperatura
15.
J Am Chem Soc ; 130(32): 10812-20, 2008 Aug 13.
Artículo en Inglés | MEDLINE | ID: mdl-18642912

RESUMEN

Reaction of NaBH4 with (tBuPOCOP)IrHCl affords the previously reported complex (tBuPOCOP)IrH2(BH3) (1) (tBuPOCOP = kappa(3)-C6H3-1,3-[OP(tBu)2]2). The structure of 1 determined from neutron diffraction data contains a B-H sigma-bond to iridium with an elongated B-H bond distance of 1.45(5) A. Compound 1 crystallizes in the space group P1 (Z = 2) with a = 8.262 (5) A, b = 12.264 (5) A, c = 13.394 (4) A, and V = 1256.2 (1) A(3) (30 K). Complex 1 can also be prepared by reaction of BH3 x THF with (tBuPOCOP)IrH2. Reaction of (tBuPOCOP)IrH2 with pinacol borane gave initially complex 2, which is assigned a structure analogous to that of 1 based on spectroscopic measurements. Complex 2 evolves H2 at room temperature leading to the borane complex 3, which is formed cleanly when 2 is subjected to dynamic vacuum. The structure of 3 has been determined by X-ray diffraction and consists of the (tBuPOCOP)Ir core with a sigma-bound pinacol borane ligand in an approximately square planar complex. Compound 3 crystallizes in the space group C2/c (Z = 4) with a = 41.2238 (2) A, b = 11.1233 (2) A, c = 14.6122 (3) A, and V = 6700.21 (19) A(3) (130 K). Reaction of (tBuPOCOP)IrH2 with 9-borobicyclononane (9-BBN) affords complex 4. Complex 4 displays (1)H NMR resonances analogous to 1 and exists in equilibrium with (tBuPOCOP)IrH2 in THF solutions.

16.
J Phys Chem A ; 112(29): 6667-77, 2008 Jul 24.
Artículo en Inglés | MEDLINE | ID: mdl-18593102

RESUMEN

Single crystal neutron diffraction data have been collected on a sample of enolized 3,4-diacetyl-2,5-hexanedione (tetraacetylethane, TAE) at five temperatures between 20 and 298 K to characterize the temperature-dependent behavior of the short, strong, intramolecular hydrogen bond. Upon decreasing the temperature from 298 K to 20 K, the O2-H1 distance decreases from 1.171(11) to 1.081(2) A and the O1...H1 distance increases from 1.327(10) to 1.416(6) A. The convergence of the C-O bond lengths from inequivalent distances at low temperature to identical values (1.285(4) A) at 298 K is consistent with a resonance-assisted hydrogen bond. However, a rigid bond analysis indicates that the structure at 298 K is disordered. The disorder vanishes at lower temperatures. Short intermolecular C-H...O contacts may be responsible for the ordering at low temperature. The intramolecular O...O distance (2.432 +/- 0.006 A) does not change with temperature. X-ray data at 20 K were measured to analyze the charge density and to gain additional insight into the nature of the strong hydrogen bond. Quantum mechanical calculations demonstrate that periodic boundary conditions provide significant enhancement over gas phase models in that superior agreement with the experimental structure is achieved when applying periodicity. One-dimensional potential energy calculations followed by quantum treatment of the proton reproduce the location of the proton nearer to the O2 site reasonably well, although they overestimate the O-H distance at low temperatures. The choice of the single-point energy calculation strategy for the proton potential is justified by the fact that the proton is preferably located nearer to O2 rather than being equally distant to O1 and O2 or evenly distributed (disordered) between them.


Asunto(s)
Acetileno/análogos & derivados , Electrones , Etano/análogos & derivados , Difracción de Neutrones , Temperatura , Acetileno/química , Etano/química , Enlace de Hidrógeno , Teoría Cuántica , Termodinámica , Rayos X
17.
J Trauma ; 64(2): 456-61, 2008 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-18301215

RESUMEN

BACKGROUND: Treatment of traumatic liver and spleen rupture is a major challenge for the surgeon. Because of their excellent blood supply and tissue structure, rupture of the liver and spleen is often associated with massive abdominal hemorrhage. Frequently the surgeon's only feasible option is partial or total resection of the organ. The purpose of this study was to test the hemostatic efficacy of gelatin thrombin granules (FloSeal) in a standardized severe traumatic liver and spleen rupture model in swine (representing a grade IV-V rupture) during severe hemorrhagic shock and coagulation disorder. METHODS: Standardized combined penetrating liver and spleen rupture was inflicted in 10 anesthetized swine. Hemorrhagic shock was induced after heparinization. Gelatin thrombin granules were used to treat both the ruptured liver and the ruptured spleen. Blood loss, hemostasis, and 48 hours survival rate were quantified. Cardiorespiratory parameters, activated clotting time, and plasma fibrinogen level were monitored. After 1 hour and 48 hours a second look evaluation was performed to detect any postoperative hemorrhage. Ruptures were then examined macroscopically and histologically. RESULTS: Hemostasis was achieved with FloSeal in all swine. The mean amount of FloSeal used was 14 mL +/- 2.5 mL. Macroscopic and histologic findings after 48 hours showed excellent clot integration into the surrounding tissue without any adverse effects. CONCLUSION: Gelatin thrombin granules (FloSeal) are effective in treating severe penetrating rupture of the liver and spleen even during hemorrhagic shock, retransfusion conditions, and coagulation disorder.


Asunto(s)
Esponja de Gelatina Absorbible/uso terapéutico , Hígado/lesiones , Choque Hemorrágico/terapia , Rotura del Bazo/terapia , Animales , Trastornos de la Coagulación Sanguínea/etiología , Trastornos de la Coagulación Sanguínea/terapia , Modelos Animales de Enfermedad , Femenino , Hemoglobinas/metabolismo , Hemostáticos , Hepatopatías/complicaciones , Hepatopatías/terapia , Masculino , Rotura/complicaciones , Rotura/terapia , Choque Hemorrágico/etiología , Rotura del Bazo/complicaciones , Sus scrofa , Trombina/uso terapéutico
19.
EJNMMI Res ; 8(1): 11, 2018 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-29404708

RESUMEN

BACKGROUND: 15O-Water positron emission tomography (PET) enables functional imaging of the auditory system during stimulation via a promontory electrode or cochlear implant, which is not possible using functional magnetic resonance imaging (fMRI). Although PET has been introduced in this context decades ago, its feasibility when performed during general anesthesia has not yet been explored. However, due to a shift to earlier (and bilateral) auditory implantation, the need to study children during general anesthesia appeared, since they are not able to cooperate during scanning. Therefore, we evaluated retrospectively results of individual SPM (statistical parametric mapping) analysis of 15O-water PET in 17 children studied during general anesthesia and compared them to those in 9 adults studied while awake. Specifically, the influence of scan duration, smoothing filter kernel employed during preprocessing, and cut-off value used for statistical inferences were evaluated. Frequencies, peak heights, and extents of activations in auditory and extra-auditory brain regions (AR and eAR) were registered. RESULTS: It was possible to demonstrate activations in auditory brain regions during general anesthesia; however, the frequency and markedness of positive findings were dependent on some of the abovementioned influence factors. Scan duration (60 vs. 90 s) had no significant influence on peak height of auditory cortex activations. To achieve a similar frequency and extent of AR activations during general anesthesia compared to waking state, a lower cut-off for statistical inferences (p < 0.05 or p < 0.01 vs. p < 0.001) had to be applied. However, this lower cut-off was frequently associated with unexpected, "artificial" activations in eAR. These activations in eAR could be slightly reduced by the use of a stronger smoothing filter kernel during preprocessing of the data (e.g., [30 mm]3). CONCLUSIONS: Our data indicate that it is feasible to detect auditory cortex activations in 15O-water PET during general anesthesia. Combined with the improved signal to noise ratios of modern PET scanners, this suggests reasonable prospects for further evaluation of the method for clinical use in auditory implant users. Adapted parameters for data analysis seem to be helpful to improve the proportion of signals in AR versus eAR.

20.
Crit Care ; 11(1): R17, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-17298665

RESUMEN

INTRODUCTION: Evidence-based recommendations can be made with respect to many aspects of the acute management of the bleeding trauma patient, which when implemented may lead to improved patient outcomes. METHODS: The multidisciplinary Task Force for Advanced Bleeding Care in Trauma was formed in 2005 with the aim of developing guidelines for the management of bleeding following severe injury. Recommendations were formulated using a nominal group process and the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) hierarchy of evidence and were based on a systematic review of published literature. RESULTS: Key recommendations include the following: The time elapsed between injury and operation should be minimised for patients in need of urgent surgical bleeding control, and patients presenting with haemorrhagic shock and an identified source of bleeding should undergo immediate surgical bleeding control unless initial resuscitation measures are successful. A damage control surgical approach is essential in the severely injured patient. Pelvic ring disruptions should be closed and stabilised, followed by appropriate angiographic embolisation or surgical bleeding control, including packing. Patients presenting with haemorrhagic shock and an unidentified source of bleeding should undergo immediate further assessment as appropriate using focused sonography, computed tomography, serum lactate, and/or base deficit measurements. This guideline also reviews appropriate physiological targets and suggested use and dosing of blood products, pharmacological agents, and coagulation factor replacement in the bleeding trauma patient. CONCLUSION: A multidisciplinary approach to the management of the bleeding trauma patient will help create circumstances in which optimal care can be provided. By their very nature, these guidelines reflect the current state-of-the-art and will need to be updated and revised as important new evidence becomes available.


Asunto(s)
Antifibrinolíticos/uso terapéutico , Transfusión Sanguínea , Hemorragia/terapia , Técnicas Hemostáticas , Heridas y Lesiones/complicaciones , Trastornos de la Coagulación Sanguínea , Sustitutos Sanguíneos/uso terapéutico , Embolización Terapéutica , Tratamiento de Urgencia , Hemorragia/diagnóstico , Hemorragia/etiología , Humanos , Resucitación , Choque Hemorrágico/diagnóstico , Choque Hemorrágico/etiología , Choque Hemorrágico/terapia , Factores de Tiempo , Heridas y Lesiones/diagnóstico , Heridas y Lesiones/cirugía
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