Removal of a broken intramedullary femoral nail with an unusual pattern of breakage: a case report

To the best of our knowledge, only 3 cases, including the present case, have been reported with a three part broken pattern. However, this is the first case associated with a distal locking screw broken. We report the case of a 31-year-old patient who sustained an open femoral shaft fracture . The fracture was stabilized with a Kuntcher femoral nail. After 7 months of the initial surgery he presented with a three part broken intramedullary nail and the distal locking screw broken. We used a combined technique for the removal of the nail through the nonunion fracture site; we used a pull out technique for the middle fragment and a curved thin hook for the distal fragment. Then we applied bone allograft and stabilized with a cannulated intramedullary femoral nail (Synthes, Oberdorf, Switzerland). After 2 years of follow up the nonunion was consolidated and the patient presented a good clinical outcome. This is of particular interest because it is a unique case and the association with a broken distal locking screw is reported for the first time in this study. A combination of methods through the nonunion site approach and an alternative instrumental is a good method for the removal of a hollow femoral intramedullary nail with this unusual pattern of breakage

Cophenetic correlation analysis as a strategy to select phylogenetically informative proteins: an example from the fungal kingdom

<p>Abstract</p> <p>Background</p> <p>The construction of robust and well resolved phylogenetic trees is important for our understanding of many, if not all biological processes, including speciation and origin of higher taxa, genome evolution, metabolic diversification, multicellularity, origin of life styles, pathogenicity and so on. Many older phylogenies were not well supported due to insufficient phylogenetic signal present in the single or few genes used in phylogenetic reconstructions. Importantly, single gene phylogenies were not always found to be congruent. The phylogenetic signal may, therefore, be increased by enlarging the number of genes included in phylogenetic studies. Unfortunately, concatenation of many genes does not take into consideration the evolutionary history of each individual gene. Here, we describe an approach to select informative phylogenetic proteins to be used in the Tree of Life (TOL) and barcoding projects by comparing the cophenetic correlation coefficients (CCC) among individual protein distance matrices of proteins, using the fungi as an example. The method demonstrated that the quality and number of concatenated proteins is important for a reliable estimation of TOL. Approximately 40–45 concatenated proteins seem needed to resolve fungal TOL.</p> <p>Results</p> <p>In total 4852 orthologous proteins (KOGs) were assigned among 33 fungal genomes from the Asco- and Basidiomycota and 70 of these represented single copy proteins. The individual protein distance matrices based on 531 concatenated proteins that has been used for phylogeny reconstruction before <abbrgrp><abbr bid="B14">14</abbr></abbrgrp> were compared one with another in order to select those with the highest CCC, which then was used as a reference. This reference distance matrix was compared with those of the 70 single copy proteins selected and their CCC values were calculated. Sixty four KOGs showed a CCC above 0.50 and these were further considered for their phylogenetic potential. Proteins belonging to the cellular processes and signaling KOG category seem more informative than those belonging to the other three categories: information storage and processing; metabolism; and the poorly characterized category. After concatenation of 40 proteins the topology of the phylogenetic tree remained stable, but after concatenation of 60 or more proteins the bootstrap support values of some branches decreased, most likely due to the inclusion of proteins with lowers CCC values. The selection of protein sequences to be used in various TOL projects remains a critical and important process. The method described in this paper will contribute to a more objective selection of phylogenetically informative protein sequences.</p> <p>Conclusion</p> <p>This study provides candidate protein sequences to be considered as phylogenetic markers in different branches of fungal TOL. The selection procedure described here will be useful to select informative protein sequences to resolve branches of TOL that contain few or no species with completely sequenced genomes. The robust phylogenetic trees resulting from this method may contribute to our understanding of organismal diversification processes. The method proposed can be extended easily to other branches of TOL.</p

Purification and In Vitro Activity of Mitochondria Targeted Nitrogenase Cofactor Maturase NifB

Active NifB is a milestone in the process of engineering nitrogen fixing plants. NifB is an extremely O2-sensitive S-adenosyl methionine (SAM)?radical enzyme that provides the key metal cluster intermediate (NifB-co) for the biosyntheses of the active-site cofactors of all three types of nitrogenases. NifB and NifB-co are unique to diazotrophic organisms. In this work, we have expressed synthetic codon-optimized versions of NifB from the ?-proteobacterium Azotobacter vinelandii and the thermophilic methanogen Methanocaldococcus infernus in Saccharomyces cerevisiae and in Nicotiana benthamiana. NifB proteins were targeted to the mitochondria, where O2 consumption is high and bacterial-like [Fe-S] cluster assembly operates. In yeast, NifB proteins were co-expressed with NifU, NifS, and FdxN proteins that are involved in NifB [Fe?S] cluster assembly and activity. The synthetic version of thermophilic NifB accumulated in soluble form within the yeast cell, while the A. vinelandii version appeared to form aggregates. Similarly, NifB from M. infernus was expressed at higher levels in leaves of Nicotiana benthamiana and accumulated as a soluble protein while A. vinelandii NifB was mainly associated with the non-soluble cell fraction. Soluble M. infernus NifB was purified from aerobically grown yeast and biochemically characterized. The purified protein was functional in the in vitro FeMo-co synthesis assay. This work presents the first active NifB protein purified from a eukaryotic cell, and highlights the importance of screening nif genes from different organisms in order to sort the best candidates to assemble a functional plant nitrogenase

A polytrauma patient with an unusual posterior fracture-dislocation of the femoral head: a case report

We report a case of a 27-year-old man who was involved in a high-speed car accident. He sustained multiple organ damage including multiple brain petechiae suggesting diffuse axonal damage, aortic dissection, retroperitoneal haematoma and a fracture-dislocation of the right hip with a femoral head fracture and an ipsilateral intertrochanteric fracture. Due to the general condition of the patient, physiological stabilisation was prioritized, and at 2 weeks the fracture-dislocation of the hip was treated with a proximal femoral nail for the intertrochanteric fracture and Herbert screws for the femoral head fracture. Postoperatively, two episodes of recurrent hip dislocation occurred, and this was stabilized eventually with a Steinman pin inserted across the hip joint and taken out 1 month later. Weight-bearing was allowed according to clinical and radiographical assessments. Heterotopic ossification developed around the hip joint, but without evidence of AVN or osteoarthritis. At 18-months follow-up, the fractures had healed and the patient had a Harris Hip score of 79.1. Anatomical reduction and stable fixation of fracture-dislocations of the hip are important for achieving an acceptable result

Sequential and Differential Interaction of Assembly Factors During Nitrogenase MoFe Protein Maturation

Nitrogenases reduce atmospheric nitrogen, yielding the basic inorganic molecule ammonia. The nitrogenase MoFe protein contains two cofactors, a [7Fe-9S-Mo-C-homocitrate] active-site species, designated FeMo-cofactor, and a [8Fe-7S] electron-transfer mediator called P-cluster. Both cofactors are essential for molybdenum-dependent nitrogenase catalysis in the nitrogen-fixing bacterium Azotobacter vinelandii. We show here that three proteins, NafH, NifW, and NifZ, copurify with MoFe protein produced by an A. vinelandii strain deficient in both FeMo-cofactor formation and P-cluster maturation. In contrast, two different proteins, NifY and NafY, copurified with MoFe protein deficient only in FeMo-cofactor formation. We refer to proteins associated with immature MoFe protein in the following as “assembly factors.” Copurifications of such assembly factors with MoFe protein produced in different genetic backgrounds revealed their sequential and differential interactions with MoFe protein during the maturation process. We found that these interactions occur in the order NafH, NifW, NifZ, and NafY/NifY. Interactions of NafH, NifW, and NifZ with immature forms of MoFe protein preceded completion of P-cluster maturation, whereas interaction of NafY/NifY preceded FeMo-cofactor insertion. Because each assembly factor could independently bind an immature form of MoFe protein, we propose that subpopulations of MoFe protein–assembly factor complexes represent MoFe protein captured at different stages of a sequential maturation process. This suggestion was supported by separate isolation of three such complexes, MoFe protein–NafY, MoFe protein–NifY, and MoFe protein–NifW. We conclude that factors involved in MoFe protein maturation sequentially bind and dissociate in a dynamic process involving several MoFe protein conformational states

Purification and characterization of NifB from Chloroflexi

NifB tiene un papel crucial en la biogénesis de la nitrogenasa, enzima responsable de la fijación del nitrógeno atmosférico (N2) a amonio (NH3), proceso conocido como Fijación Biológica del Nitrógeno. NifB es una proteína que pertenece a una familia de proteínas conocida como ?SAM-radical proteins? y cataliza la síntesis del cofactor metálico NifB-co, [Fe8-S9-C] a partir de dos ?clusters? sulfo-férricos del tipo [Fe4-S4] y dos moléculas de SAM. NifB-co sirve como intermediario en la biosíntesis de los sitios activos (cofactores metálicos) de todas las nitrogenasas conocidas, donde la más común es la nitrogenasa de molibdeno, cuyo cofactor, conocido como FeMo-co, consiste en [Fe7-S9-C-Mo-Homocitrato]. Inicialmente, NifB fue purificado a partir de microorganismos diazotrofos como Azotobacter vinelandii o Klebsiella oxytoca. Ambas especies son ?-proteobacterias mesofílicas de vida libre, distribuidas en suelos cuyo NifB presenta una arquitectura con dos dominios, el dominio SAM-radical y el dominio NifX. Sin embargo, en estudios recientes se ha purificado satisfactoriamente NifBs procedentes de metanógenos termofílicos que presentan únicamente el dominio SAM-radical en su estructura, expresados de forma heteróloga en E. coli. En el trabajo presentado en el congreso ENFC 2018, se ha purificado y caracterizado NifB de una bacteria perteneciente al filo Chloroflexi, Roseiflexus sp. RS.1. Este NifB termorresistente, es estructuralmente similar a NifBs procedentes de arqueas y únicamente presenta el dominio SAM. En este estudio se muestras las propiedades bioquímicas de NifB de Roseiflexus y su capacidad para sintetizar NifB-co en ensayos de síntesis e inserción de FeMo-co in vitro, para la activación de la enzima nitrogenasa. NifB de Roseiflexus es termorresistente, llega a alcanzar un total de 9 átomos de hierro por monómero y presenta propiedades espectroscópicas compatibles con la presencia de tres clusters [Fe4-S4] tal y como se ha reportado para su homólogo NifB de Methanocalcococcus infernus. ----------ABSTRACT---------- NifB has a crucial role in the biogenesis of active nitrogenase, the enzyme responsible of fixing atmospheric N2 to NH3 in a process known as biological nitrogen fixation (BNF). NifB is a SAM-radical protein that catalyzes the synthesis of a metal cluster, NifB-co [Fe8-S9-C], from two [Fe4-S4] cluster units and a molecule of SAM. NifB-co serves as intermediate in the biosynthesis of the active-site cofactors of all known nitrogenases(1,2). NifB has been purified from mesophilicγ–proteobacteria, having dual domain architectures based on a SAM-radical domain and a NifX-like domain(3). However, recent studies have successfully used NifB proteins from thermophillic methanogens that present a SAM-radical-domain-only architecture(4,5). In this work, NifB from Roseiflexus sp. RS-1 was heterologously expressed in Escherichia coli and purified to be used as adiitional model to further understand how NifB proteins synthesize NifB-co. Roseiflexus sp. RS-1 is a filamentous bacterium that belongs to the phylum Chloroflexi. It has thermophilic lifestyle, growing at 60ºC. This phylum is found near the most primitive branches of the phylogenetic tree, constituting an interesting candidate to study the most primitive forms of NifB and its co-evolution with the nitrogenase complex

Distal tibial fracture below a total knee arthroplasty: retrograde intramedullary nailing as an alternative method of treatment: a case report

An 85-year-old woman with a history of insulin-dependent diabetes mellitus, hypertension, and chronic venous insufficiency with underlying venous stasis who sustained a fall in her house presented to the emergency room with a displaced distal diaphyseal tibial fracture and a stable total knee arthroplasty. At her third day of admission, an intramedullary nail was inserted in a retrograde fashion through the calcaneus and talus into her tibial shaft to stabilize the fracture; there were no postoperative complications. Three years after surgery, the patient remains pain-free, the fracture had united, and her functional status is the same as it was before the fracture. There are different options for solving these types of fractures. Nonoperative, external fixation, conventional or locking plates and antegrade and retrograde intramedullary nailing could be used; however, they should be weighed against the particular issues of the patient involved. We think that a retrograde nailing technique through the calcaneotalotibial axis could be an alternative method for these types of fractures in a fragile patient with important comorbidities with few complications and good functional outcome

Biosynthesis of Nitrogenase Cofactors

48 Pág.Nitrogenase harbors three distinct metal prosthetic groups that are required for its activity. The simplest one is a [4Fe-4S] cluster located at the Fe protein nitrogenase component. The MoFe protein component carries an [8Fe-7S] group called P-cluster and a [7Fe-9S-C-Mo-R-homocitrate] group called FeMo-co. Formation of nitrogenase metalloclusters requires the participation of the structural nitrogenase components and many accessory proteins, and occurs both in situ, for the P-cluster, and in external assembly sites for FeMo-co. The biosynthesis of FeMo-co is performed stepwise and involves molecular scaffolds, metallochaperones, radical chemistry, and novel and unique biosynthetic intermediates. This review provides a critical overview of discoveries on nitrogenase cofactor structure, function, and activity over the last four decades.This work has been funded by the Bill & Melinda Gates Foundation Grant No. OPP1143172 and by FEDER / Ministerio de Ciencia, Innovación y Universidades – Agencia Estatal de Investigación / Proyecto 2017-88475-R.Peer reviewe

Medial complex elbow dislocation: an unusual pattern of injury

A 47-year-old man sustained a medial complex dislocation of the right elbow. After initial evaluation, closed reduction was performed. On examination under general anesthesia, the elbow was unstable under varus and valgus stress. Computed tomography scan showed a medial epicondyle and a coronoid fracture. Both medial and lateral approaches were used to fix the epicondylar fragment, the coronoid fragment, and the complex damage to the soft tissues. Immobilization in a cast for 1 week followed by early motion in a dynamic orthosis resulted in a good outcome. Follow up at 2 years showed a range of motion of 110 degrees of flexion-extension and 170 degrees of pronation-supination. Radiographs showed no significant arthritis or heterotopic ossifications