Management of complications of mega-implants following treatment of primary and periprosthetic fractures of the lower extremities.

In recent years, indications for implanting mega-implants were established in managing major bone defects linked to revision arthroplasty due to loosening, periprosthetic fractures, re-implantation following periprosthetic joint infection, non-union following fractures as well as complex intraarticular primary fractures. This study was conducted to discuss and analyze the strategy of diagnosis and management of complications following the use of mega-implants in treating primary and periprosthetic fractures of the lower extremities. This is a monocentric retrospective study. Patients aged ≥ 18 years who underwent implantation of a megaendoprosthesis due to periprosthetic or primary fractures of the lower extremity between January 2010 and February 2023 were identified from the authors' hospital information system. We identified 96 patients with equal numbers of fractures (71 periprosthetic fractures and 25 primary fractures). 90 cases out of 96 were investigated in this study. The drop-out rate was 6.25% (six cases). The average follow-up period was 22 months (1 to 8 years) with a minimum follow-up of 1 year. The diagnosis of complications was provided on the basis of subjective symptoms, clinical signs, radiological findings and laboratory investigations such as C-reactive protein, leucocyte count and the microbiological findings. The indications for implantations of modular mega-implants of the lower extremities were periprosthetic fractures (65 cases/72.22%) and primary fractures (25 cases/27.78%). Pathological fractures due to malignancy were encountered in 23 cases (25.56%), in one case due to primary tumor (1.11%) and 22 cases due to metastatic lesions (24.44%). Two cases (2.22%) presented with primary intraarticular fractures with severe osteoporosis and primary arthrosis. In all cases with malignancy staging was performed. Regarding localization, proximal femur replacement was encountered in 60 cases (66.67%), followed by distal femur replacement (28 cases/31.11%) and total femur replacement (2 cases/2.22%). The overall complication rate was 23.33% (21 complications in 21 patients). The most common complication was dislocation which was encountered in nine cases (10%), all following proximal femoral replacement (9 cases out of 60, making 15% of cases with proximal femoral replacement). The second most common complication was infection (six cases, 6.67%), followed by four aseptic loosenings (4.44%), further intraoperative periprosthetic fracture in one case (1.11%) and a broken implant in one case (1.11%). We noticed no cases with wear and tear of the polyethylene components and no cases of disconnections of the modular components. Mega-endoprostheses enable versatile management options in the treatment of primary and periprosthetic fractures of the lower extremities. The rate of complications such as loosening, implant failure, dislocation and infection are within an acceptable range in this preliminary analysis. However, implantation of mega-endoprostheses must be strictly indicated due the limited salvage options following surgery.

Butyrate supplementation in the liquid diet of dairy calves leads to a rapid recovery from diarrhea and reduces its occurrence and relapses in the preweaning period.

The present study aimed to evaluate the effect of continuous butyrate administration in dairy calves' liquid diet considering diarrhea, metabolic profile, gastrointestinal development, and corporal growth. Immediately after birth, calves were randomly allocated into 2 groups of 62 calves (50 females and 12 males), with access to water and a solid feed ad libitum. The butyrate group (BG) received 4 g/d of sodium butyrate (Admix Easy, Adisseo) diluted in the whole milk, and the control group (CG) received whole milk with no supplementation. Sodium butyrate was administered from d 1 of life until the weaning at 90 d. Feces consistency was assessed daily for the first 30 d of life and characterized by scores from 0 to 4 (0 and 1 for normal, and 2, 3, and 4 for abnormal feces). Diarrhea was diagnosed when the animals had abnormal feces and fever. Morbidity, recurrence, mortality, and lethality data were recorded and compared between the groups. Average daily gain (ADG) and corporal growth (body weight, thoracic perimeter, height at the withers, and croup width) were evaluated weekly, from the first day to d 30, and later at 45, 60, and 90 d of life. Blood samples were taken weekly for up to 30 d to determine the circulating levels of total calcium, phosphorus, chloride, bicarbonate, glucose, ß-hydroxybutyrate, and nonesterified fatty acids. The males were euthanized at 15 (n = 6 per group) and 30 d (n = 6 per group) for morphometric, histological, and gene expression analysis of the gastrointestinal tract. The results showed that the BG had a lower rate of morbidity (BG = 30% vs. CG = 50%) and recurrence (BG = 26.7% vs. CG = 60%) of diarrhea than the CG. In addition, the BG had abnormal feces for a shorter period (BG = 4.64 ± 0.47 d vs. CG = 8.6 ± 0.65 d). The ADG tended to be higher in BG than CG up to 30 and 60 d. Metabolic evaluations showed the lowest levels of glucose and highest levels of nonesterified fatty acids in BG. On d 30 of life, rumen papillae length, papilla area, duodenum villus length, and crypt depth were higher in BG than in CG. The duodenal gene expression at 30 d showed that animals with diarrhea episodes that did not receive butyrate had the highest levels of transcripts for the LCT and GLP2 genes. In addition, in different ways, both butyrate and neonatal diarrhea affected the gene expression of IGF1, SLC5A1, and AQP3. These results allow us to conclude that continuous supplementation with sodium butyrate improves gastrointestinal development, reduces the occurrence of diarrhea, and makes clinical conditions milder with faster recovery, favoring a higher ADG in the first 30 and 60 d of life. Based on these results, we conclude that sodium butyrate can be indicated for liquid diet supplementation to accelerate gastrointestinal tract development and prevent severe cases of neonatal diarrhea, tending to improve average daily gain until weaning.

Beam-pointing verification using x-ray pinhole cameras on the 60-beam OMEGA laser.

On the OMEGA laser system, the beam-pointing accuracy is verified by irradiating a 4 mm diameter Au-coated spherical target with ∼23 kJ of laser energy. Up to ten x-ray pinhole cameras record the x-ray emission from all 60-beam spots. A new set of algorithms has been developed to improve the accuracy of the pointing evaluation. An updated edge-finding procedure allows one to infer the center of the sphere with subpixel accuracy. A new approach was introduced to back-propagate the pixel locations on the 2D image to the 3D surface of the sphere. A fast Fourier transform-based de-noising method significantly improves the signal-to-noise of the data. Based on the beam-pointing analysis, hard-sphere calculations of the laser-drive illumination uniformity on the target surface and the decomposition of the illumination distribution into lower order modes (1-10) are evaluated.

3D Simulations Capture the Persistent Low-Mode Asymmetries Evident in Laser-Direct-Drive Implosions on OMEGA.

Spherical implosions in inertial confinement fusion are inherently sensitive to perturbations that may arise from experimental constraints and errors. Control and mitigation of low-mode (long wavelength) perturbations is a key milestone to improving implosion performances. We present the first 3D radiation-hydrodynamic simulations of directly driven inertial confinement fusion implosions with an inline package for polarized crossed-beam energy transfer. Simulations match bang times, yields (separately accounting for laser-induced high modes and fuel age), hot spot flow velocities and direction, for which polarized crossed-beam energy transfer contributes to the systematic flow orientation evident in the OMEGA implosion database. Current levels of beam mispointing, imbalance, target offset, and asymmetry from polarized crossed-beam energy transfer degrade yields by more than 40%. The effectiveness of two mitigation strategies for low modes is explored.

Dispersão da lidocaína administrada por via epidural em cães posicionados em decúbito lateral ou esternal / [Dispersion of lidocaine epidurally administered to dogs positioned on lateral or external decubitus]

O objetivo do estudo foi verificar clinicamente a dispersão da lidocaína no espaço epidural de cães posicionados em diferentes decúbitos. Foram utilizados 16 cães, com peso médio de 17,5 quilogramas. Esses foram tranquilizados com acepromazina, anestesiados com propofol e alocados em dois grupos, conforme o decúbito de posicionamento: decúbito esternal (GE) e decúbito lateral direito (GLD). Ambos os grupos receberam lidocaína a 2%, no volume de 0,25mL/kg, e permaneceram no mesmo decúbito por 20 minutos. Em seguida, avaliou-se o bloqueio dos membros pélvicos e a extensão do bloqueio, a partir da sétima vértebra lombar, por meio de pinçamento interdigital e do panículo paravertebral. Foi, então, realizada cirurgia de orquiectomia. Após tal procedimento, avaliou-se o tempo total de bloqueio dos membros pélvicos. Todos os cães apresentaram bloqueio bilateral, sem diferenças quanto à extensão cranial entre os grupos, sendo a mediana de 7,5 (1-14) vértebras para GE e de 4 (1-14) para GLD. O tempo de bloqueio dos membros direito e esquerdo foi de 123 ± 26 e 130 ± 20 minutos, para GE, e de 120 ± 21 e 121 ± 20 minutos, para GLD, sem diferenças entre os grupos ou entre os membros. Conclui-se que o decúbito não interfere na distribuição da lidocaína administrada por via epidural.(AU)

The aim of this study was to clinically verify the dispersion of lidocaine in the epidural space of dogs placed in different positions. Sixteen dogs with an average weight of 17.5 kilograms were used. These were tranquilized with acepromazine, anesthetized with propofol and allocated to two groups: sternal decubitus (GE) and right lateral decubitus (GLD). Both groups received 2% of lidocaine in the volume of 0.25mL/kg and remained in the same position for 20 minutes. The blocking of the pelvic limbs and the extension of it from the seventh lumbar vertebra were evaluated by means of interdigital and paravertebral panniculus clamping. Orchiectomy surgery was then performed. Afterwards, the total blocking time of the pelvic limbs was evaluated. All dogs presented bilateral blocking, with no differences in cranial extension between groups, with a median of 7.5 (1-14) vertebrae for GE and 4 (1-14) for GLD. The blocking time of the right and left limbs were 123 ± 26 and 130 ± 20 minutes for GE, and 120 ± 21 and 121 ± 20 minutes for GLD with no difference between groups or between limbs. It is concluded that the decubitus does not interfere with the epidural lidocaine distribution.(AU)

Investigation of an apodized imaged Hartmann wavefront sensor.

Quantitative wavefront measurements are demonstrated using a Hartmann mask re-imaged onto a camera. The wavefront is reconstructed using standard algorithms applied to the difference of beamlet centroids determined from fluence distributions obtained for two different longitudinal locations of the mask. The wavefront of the optical wave in the object plane is measured independently of imaging-system collimation. Apodization obtained with spatially dithered distributions of small transparent or opaque pixels improves the measurement accuracy by reducing the spatial-frequency content of the mask holes. Simulations and experiments demonstrate the excellent accuracy of this diagnostic over a wide range of parameters, making it suitable, for example, to characterize laser systems.

Single-shot high-resolution characterization of optical pulses by spectral phase diversity.

The concept of spectral phase diversity is proposed and applied to the temporal characterization of optical pulses. The experimental trace is composed of the measured power of a plurality of ancillary optical pulses derived from the pulse under test by adding known amounts of chromatic dispersion. The spectral phase of the pulse under test is retrieved by minimizing the error between the experimental trace and a trace calculated using the known optical spectrum and diagnostic parameters. An assembly composed of splitters and dispersive delay fibers has been used to generate 64 ancillary pulses whose instantaneous power can be detected in a single shot with a high-bandwidth photodiode and oscilloscope. The diagnostic is experimentally shown to accurately characterize pulses from a chirped-pulse-amplification system when its stretcher is detuned from the position for optimal recompression. Pulse-shape reconstruction for pulses shorter than the photodetection impulse response has been demonstrated. Various investigations of the performance with respect to the number of ancillary pulses and the range of chromatic dispersion generated in the diagnostic are presented.

Prevention of neonatal oxygen-induced brain damage by reduction of intrinsic apoptosis.

Within the last decade, it became clear that oxygen contributes to the pathogenesis of neonatal brain damage, leading to neurocognitive impairment of prematurely born infants in later life. Recently, we have identified a critical role for receptor-mediated neuronal apoptosis in the immature rodent brain. However, the contribution of the intrinsic apoptotic pathway accompanied by activation of caspase-2 under hyperoxic conditions in the neonatal brain still remains elusive. Inhibition of caspases appears a promising strategy for neuroprotection. In order to assess the influence of specific caspases on the developing brain, we applied a recently developed pentapeptide-based group II caspase inhibitor (5-(2,6-difluoro-phenoxy)-3(R,S)-(2(S)-(2(S)-(3-methoxycarbonyl-2(S)-(3-methyl-2(S)-((quinoline-2-carbonyl)-amino)-butyrylamino)propionylamino)3-methylbutyrylamino)propionylamino)-4-oxo-pentanoic acid methyl ester; TRP601). Here, we report that elevated oxygen (hyperoxia) triggers a marked increase in active caspase-2 expression, resulting in an initiation of the intrinsic apoptotic pathway with upregulation of key proteins, namely, cytochrome c, apoptosis protease-activating factor-1, and the caspase-independent protein apoptosis-inducing factor, whereas BH3-interacting domain death agonist and the anti-apoptotic protein B-cell lymphoma-2 are downregulated. These results coincide with an upregulation of caspase-3 activity and marked neurodegeneration. However, single treatment with TRP601 at the beginning of hyperoxia reversed the detrimental effects in this model. Hyperoxia-mediated neurodegeneration is supported by intrinsic apoptosis, suggesting that the development of highly selective caspase inhibitors will represent a potential useful therapeutic strategy in prematurely born infants.

Demonstration of large-aperture tiled-grating compressors for high-energy, petawatt-class, chirped-pulse amplification systems.

Two large-aperture tiled-grating (1.5 m) compressors, each consisting of four sets of tiled-grating assemblies, have been built for the OMEGA EP high-energy petawatt-class laser system. The techniques used for tiling individual tiled-grating assemblies and for optimizing the overall performance of a tiled-grating compressor are described. Both compressors achieved subpicosecond pulse duration without tiling-induced temporal degradation. A ray-tracing model predicted that the static wavefront of the grating tiles dominated focal-spot degradations when submicroradian tiling accuracy is achieved. The tiled-grating compressors delivered a tighter focal spot compared with subaperture grating compressors with single central tiles.

Large-aperture grating tiling by interferometry for petawatt chirped-pulse-amplification systems.

A tiled-grating assembly with three large-scale gratings is developed with real-time interferometric tiling control for the OMEGA EP Laser Facility. An automatic tiling method is achieved and used to tile a three-tile grating assembly with the overall wavefront reconstructed. Tiling-parameters sensitivity and focal-spot degradation from all combined tiling errors are analyzed for a pulse compressor composed of four such assemblies.

The 15-K neutron structure of saccharide-free concanavalin A.

The positions of the ordered hydrogen isotopes of a protein and its bound solvent can be determined by using neutron crystallography. Furthermore, by collecting neutron data at cryo temperatures, the dynamic disorder within a protein crystal is reduced, which may lead to improved definition of the nuclear density. It has proved possible to cryo-cool very large Con A protein crystals (>1.5 mm3) suitable for high-resolution neutron and x-ray structure analysis. We can thereby report the neutron crystal structure of the saccharide-free form of Con A and its bound water, including 167 intact D2O molecules and 60 oxygen atoms at 15 K to 2.5-A resolution, along with the 1.65-A x-ray structure of an identical crystal at 100 K. Comparison with the 293-K neutron structure shows that the bound water molecules are better ordered and have lower average B factors than those at room temperature. Overall, twice as many bound waters (as D2O) are identified at 15 K than at 293 K. We note that alteration of bound water orientations occurs between 293 and 15 K; such changes, as illustrated here with this example, could be important more generally in protein crystal structure analysis and ligand design. Methodologically, this successful neutron cryo protein structure refinement opens up categories of neutron protein crystallography, including freeze-trapped structures and cryo to room temperature comparisons.

Dynamics in the Mn2+ binding site in single crystals of concanavalin A revealed by high-field EPR spectroscopy.

EPR spectroscopy at 95 GHz was used to characterize the dynamics at the Mn(2+) binding site in single crystals of the saccharide-binding protein concanavalin A. The zero-field splitting (ZFS) tensor of the Mn(2+) was determined from rotation patterns in the a-c and a-b crystallographic planes, acquired at room temperature and 4.5 K. The analysis of the rotation patterns showed that while at room temperature there is only one type of Mn(2+) site, at low temperatures two types of Mn(2+) sites, not related by any symmetry, are distinguished. The sites differ in the ZFS parameters D and E and in the orientation of the ZFS tensor with respect to the crystallographic axes. Temperature-dependent EPR measurements on a crystal oriented with its crystallographic a axis parallel to the magnetic field showed that as the temperature increases, the two well-resolved Mn(2+) sextets gradually coalesce into a single sextet at room temperature. The line shape changes are characteristic of a two-site exchange. This was confirmed by simulations which gave rates in the range of 10(7)-10(8) s(-1) for the temperature range of 200-266 K and an activation energy of 23.8 kJ/mol. This dynamic process was attributed to a conformational equilibrium within the Mn(2+) binding site which freezes into two conformations at low temperatures.

Direct determination of the positions of the deuterium atoms of the bound water in -concanavalin A by neutron Laue crystallography.

The correct positions of the deuterium (D) atoms of many of the bound waters in the protein concanavalin A are revealed by neutron Laue diffraction. The approach includes cases where these water D atoms show enough mobility to render them invisible even to ultra-high resolution synchrotron-radiation X-ray crystallography. The positions of the bound water H atoms calculated on the basis of chemical and energetic considerations are often incorrect. The D-atom positions for the water molecules in the Mn-, Ca- and sugar-binding sites of concanavalin A are described in detail.

Structure of a monoclinic crystal from of cyctochrome b1 (Bacterioferritin) from E. coli.

Crystals of E. coli cytochrome b1, alias bacterioferritin, were grown fr om a low ionic strength solution. The resulting monoclniic P21 structure was solved by molecular replacement and refined using noncrystallographi c symmetries applied to the fundamental unit, consisting of two protein subunits and a single haem. From the Patterson self-rotation results it was shown that the asymmetric unit of the monoclinic crystal consists of 12 such dimers and corresponds to a complete, nearly spherical, molecule of bacterioferritin (M4 = 450 kDa) of 432 point-group symmetry. It is thus the most symmetrical cytochrome. As previously determined for the tetragonal form, the haem is located in a special position on a local twofold axis of the dimer. A bimetal centre is also observed within the four-helix bundle of each monomer; a metal-binding site is located on the fourfold axis.

Tumor necrosis factor receptors (Tnfr) in mouse fibroblasts deficient in Tnfr1 or Tnfr2 are signaling competent and activate the mitogen-activated protein kinase pathway with differential kinetics.

To dissect tumor necrosis factor receptor (Tnfr)-1 (CD120a) and Tnfr2 (CD120b)-dependent signal transduction pathways, primary fibroblasts isolated from inguinal adipose tissue of wild type (wt), tnfr1(o), tnfr2(o), and tnfr1(o)/tnfr2(o) mice were studied. The mitogen-activated protein kinases Erk1 and Erk2 were found to be tyrosine-phosphorylated and activated by Tnf treatment in all wt, tnfr1(o), and tnfr2(o) fibroblasts; the activation was down-regulated 60 min after the start of steady state Tnf treatment. Distinct kinetics of Erk1 and Erk2 activation were detected; the Tnfr1-mediated activation of Erk1 and Erk2 started more slowly and persisted for more prolonged times as compared with Tnfr2 activation. Raf-1, Raf-B, Mek-1, Mek kinase, and p90(rsk) kinases were also shown to be activated independently in a distinct time-dependent pattern through the two Tnf receptors. In addition, both Tnfr1 and Tnfr2 mediated independently the activation of the transcription factor Ap-1 albeit with parallel activation kinetics. In contrast, Tnfr1 exclusively mediated activation of NF-kappaB and fibroblast proliferation; however, Tnfr2 enhanced proliferation triggered through Tnfr1. These findings indicate distinct but also overlapping roles of Tnfr1 and Tnfr2 in primary mouse fibroblasts and suggest different regulation mechanisms of signal transduction pathways under the control of both Tnf receptors.

Crystalline alcohol dehydrogenases from the mesophilic bacterium Clostridium beijerinckii and the thermophilic bacterium Thermoanaerobium brockii: preparation, characterization and molecular symmetry.

Two tetrameric NADP(+)-dependent bacterial secondary alcohol dehydrogenases have been crystallized in the apo- and the holo-enzyme forms. Crystals of the holo-enzyme from the mesophilic Clostridium beijerinckii (NCBAD) belong to space group P2(1)2(1)2(1) with unit-cell dimensions a = 90.5, b = 127.9, c = 151.4 A. Crystals of the apo-enzyme (CBAD) belong to the same space group with unit-cell dimensions a = 80.4, b = 102.3, c = 193.5 A. Crystals of the holo-enzyme from the thermophilic Thermoanaerobium brockii (NTBAD) belong to space group P6(1(5)) (a = b = 80.6, c = 400.7 A). Crystals of the apo-form of TBAD (point mutant GI98D) belong to space group P2(1) with cell dimensions a = 123.0, b = 84.8, c = 160.4 A beta = 99.5 degrees. Crystals of CBAD, NCBAD and NTBAD contain one tetramer per asymmetric unit. They diffract to 2.0 A resolution at liquid nitrogen temperature. Crystals of TBAD(GI98D) have two tetramers per asymmetric unit and diffract to 2.7 A at 276 K. Self-rotation analysis shows that both enzymes are tetramers of 222 symmetry.

Structure solution of a cubic crystal of concanavalin A complexed with methyl alpha-D-glucopyranoside.

The solution of the cubic crystal form (a = 167.8 A) of concanavalin A complexed with the monosaccharide methyl alpha-D-glucopyranoside is described. The space group has been determined as I2(1)3 rather than I23. The use of cadmium to replace cobalt at the transition metal-ion binding site and to replace calcium at its binding site proved to be crucial to the successful solution of the crystal structure. The relatively small isomorphous signals of 21 e(-) for the replacement of cobalt and 28 e(-) for the replacement of calcium, yielded interpretable difference Patterson maps. The electron-density map calculated in space group I2(1)3 at 5.4 A resolution, based on phases derived from single- and double-substituted cadmium differences, revealed a classical concanavalin A tetramer of 222 point symmetry, as seen in all the known crystal structures of concanavalin A. Rigid-body refinement at 3.6 A using the refined coordinates of saccharide-free concanavalin A converged to an R factor of 27.4%. A molecular-replacement analysis, consistent with this crystal structure, and initial experiences in the incorrect space group I23 are described as these also prove to be instructive.

Properties of a crystal of the complex of methyl D-arabinofuranoside with concanavalin A.

The complex of methyl alpha-D-arabinofuranoside with concanavalin A crystallizes in the orthorhombic space group P2(1)22(1) with cell dimensions a = 97.5, b = 87.0 and c = 61.5 A. The asymmetric unit contains one dimer and the unit cell consists of two tetrahedral clusters of point-group symmetry 222. The crystals diffract to 2.0 A resolution.

Refined structure of concanavalin A complexed with methyl alpha-D-mannopyranoside at 2.0 A resolution and comparison with the saccharide-free structure.

The three-dimensional structure of the complex between methyl alpha-D-mannopyranoside and concanavalin A has been refined at 2.0 A resolution. Diffraction data were recorded from a single crystal (space group P2(1)2(1)2(1), a = 123.7, b = 128.6, c = 67.2 A) using synchrotron radiation at a wavelength of 1.488 A. The final model has good geometry and an R factor of 19.9% for 58 871 reflections (82% complete), within the resolution limits of 8 to 2 A, with F > 1.0sigma(F). The asymmetric unit contains four protein subunits arranged as a dimer of dimers with approximate 222 point symmetry. Each monomer binds one saccharide molecule. Each sugar is bound to the protein by hydrogen bonds and van der Waals contacts. Although the four subunits are not crystallographically equivalent, the protein-saccharide interactions are nearly identical in each of the four binding sites. The differences that do occur between the four sites are in the structure of the water network which surrounds each saccharide; these networks are involved in crystal packing. The structure of the complex is compared with a refined saccharide-free concanavalin A structure. The saccharide-free structure is composed of crystallographically identical subunits, again assembled as a dimer of dimers, but with exact 222 symmetry. In the saccharide complex the tetramer association is different in that the monomers tend to separate resulting in fewer intersubunit interactions. The average temperature factor of the mannoside complex is considerably higher than that of the saccharide-free protein. The binding site in the saccharide-free structure is occupied by three ordered water molecules and the side chain of Asp71 from a neighbouring molecule in the crystal. These occupy positions similar to those of the four saccharide hydroxyls which are hydrogen bonded to the site. Superposition of the saccharide-binding site from each structure shows that the major changes on binding involve expulsion of these ordered solvents and the reorientation of the side chain of Tyrl00. Overall the surface accessibility of the saccharide decreases from 370 to 100 A(2) when it binds to the protein. This work builds upon the earlier studies of Derewenda et al. [Derewenda, Yariv, Helliwell, Kalb (Gilboa), Dodson, Papiz, Wan & Campbell (1989). EMBO J. 8, 2198-2193] at 2.9 A resolution, which was the first detailed study of lectin-saccharide interactions.