Silicon limitation facilitates virus infection and mortality of marine diatoms.

Diatoms are among the most globally distributed and ecologically successful organisms in the modern ocean, contributing upwards of 40% of total marine primary productivity1,2. By converting dissolved silicon into biogenic silica, and photosynthetically fixing carbon dioxide into particulate organic carbon, diatoms effectively couple the silicon (Si) and carbon cycles and ballast substantial vertical flux of carbon out of the euphotic zone into the mesopelagic and deep ocean3-5. Viruses are key players in ocean biogeochemical cycles6,7, yet little is known about how viral infection specifically impacts diatom populations. Here, we show that Si limitation facilitates virus infection and mortality in diatoms in the highly productive coastal waters of the California Current Ecosystem. Using metatranscriptomic analysis of cell-associated diatom viruses and targeted quantification of extracellular viruses, we found a link between Si stress and the early, active and lytic stages of viral infection. This relationship was also observed in cultures of the bloom-forming diatom Chaetoceros tenuissimus, where Si stress accelerated virus-induced mortality. Together, these findings contextualize viruses within the ecophysiological framework of Si availability and diatom-mediated biogeochemical cycling.

Influence of the cause of the revision on the outcome after revision knee arthroplasty with condylar constrained implant. / Influencia de la causa de revisión en el resultado tras revisión protésica de rodilla con implante varo-valgo constreñido.

INTRODUCTION: Revision total knee arthroplasty (TKA) is a common procedure with varying results depending on the cause. Our objective was to compare the clinical and radiological outcomes in patients undergoing aseptic revision versus revision due to prosthetic infection. MATERIAL AND METHODS: The study included 41 patients who underwent TKA revision with the same varus-valgus constrained implant. In all cases a clinical evaluation was performed including pain, range of motion (ROM), Knee Society Score (KSS), complications, as well as radiological study. A comparative analysis was performed on the pre- and postoperative results between septic and aseptic groups. The mean follow-up was 6 years. RESULTS: ROM had a mean increase of 17 degrees (p<.01). KSS and functional KSS improved significantly postoperatively. In the radiological study, joint interline and limb alignment were restored in all cases. Radiolucencies were found in 36.5% of cases; however they were unrelated to the appearance of loosening of the implant. There were complications in 29.2% of cases, mostly related to the surgical wound. Mobility, KSS, KSS functional and satisfaction at follow-up were better in the septic group. Implant survival was 95% at follow-up. CONCLUSION: Revision arthroplasty with constrained varus-valgus implant is safe, and has successful mid-term results despite the cause of the replacement procedure.

Early inflammatory response in polytraumatized patients: Cytokines and heat shock proteins. A pilot study.

INTRODUCTION: In the initial phases after polytrauma there is an hyperinflammatory state that sometimes leads to multiple organ dysfunction syndrome (MODS) and death, and that appears to be responsible for posttraumatic immunosuppression; among the trigger endogenous stimuli, heat shock proteins (HSPs) have been proposed. The objectives of this study were to analyze if some inflammatory mediators can be considered prognostic biomarkers of outcome, and the possible role of HSPA1A in posttraumatic immunosuppression. HYPOTHESIS: Cytokines and HSPs could be early prognostic biomarkers of inflammatory and immune response in polytrauma patients. MATERIALS AND METHODS: A prospective observational descriptive pilot study was carried out, evaluating the early inflammatory and stress response of 18 polytraumatized patients (ISS>16) on hospital admission, at 12hours, 24hours, and 48hours posttrauma. Variable means were compared using non-parametric tests; qualitative and quantitative variables were analyzed using a Spearman's correlation test. RESULTS: Seven patients met criteria for MODS. Statistically significant changes were recorded in leukocyte count, C-reactive-protein (CRP), IL-6, TNF-α, and IL-1ß concentrations. HSPA1A levels were significantly higher immediately after the accident followed by gradual lowering. Anti-Hsp70 antibodies showed a significant reduction in all the studied time-points. MODS did not influence either plasma levels of leukocytes, fibrinogen, RCP or anti-Hsp70, but patients with MODS had higher plasma levels of IL-6 and TNF-α and a slower decrease of HSPA1A concentrations. DISCUSSION: The higher serum concentrations of TNF-α and IL-6 found in patients with MODS, suggests a possible role as potential early predictive markers for systemic inflammatory response and clinical complications. The higher levels of HSPA1A in patients with MODS, allows proposing HSPA1A as a useful prognostic trauma biomarker early after severe injury and to consider a "damage control surgery". The significant reduction in the levels of anti-Hsp70 antibodies could reflect a part of posttraumatic immunosuppression and hydrocortisone treatment might be suggested. LEVEL III: case-control study.

[Removal due to cut-out effect in pertrochanteric femoral fractures: what is the rescue treatment of choice?]. / Desmontaje por efecto cut-out en el enclavado de fracturas pertrocantéreas de fémur: ¿cuál es el tratamiento de rescate de elección?

OBJECTIVE: The goal of the study was to compare functional results in different treament options in cutting-out, and analize factors associated to failure. MATERIAL AND METHODS: Retrospective cohort study in 56 patients diagnosed with cutting-out between 2000-2010. Groups were based on rescue treatment: arthroplasty versus alternative treatment. Demographics, fracture characteristics, osteosynthesis, tip to apex distance (TAD), follow-up, complications, and final functional capacity were analyzed. RESULTS: Rescue treatment: 36 (64.28%) hip replacement (arthroplasty group), and 20 (35.72%) alternative treatment preserving femoral head (alternative group). Groups comparable on demographic parameters, fracture pattern and osteosynthesis characteristics. Radiography analysis: low inter-observer variability (k=0.83, 95% CI 0.78-0.88), mean TAD 28.66mm (arthroplasty group 32.9mm, 21.5mm control group; p=0.01), insufficient fracture reduction 39.3% (p=0.001). Cutting-out diagnosis median 60 days (arthroplasty group 90 days, 18 days alternative group; p=0.001). Follow up at least 12 months from rescue treatment. Similar complications rate in both groups (p=0.16). Re-operation rate 3.57% (11.7% arthroplasty group, alternative group 0%; p=0.01). Better final functional capacity in arthroplasty group (p=0.004). DISCUSSION: Hip arthroplasty offers better results, being considered the gold standard in geriatric patients, although re-operation rate is higher. We recommend new nailing before arthroplasty in early failure (4 weeks) in patients with femoral head integrity. An insufficient fracture reduction is the main short term factor predicting failure; and TAD higher than 20mm is a middle-long term one.

[SECOT consensus on painful knee replacement]. / Consenso SECOT sobre artroplastia de rodilla dolorosa.

The opinions of 21 experts in knee surgery were evaluated in this study, using a DELPHI questionnaire method in two successive rounds, on 64 controversial scenarios that covered both the diagnosis and possible treatment of painful knee replacements. The level of consensus was significantly unanimous in 42 items and of the design in 5, with no agreement in 17 of the questions presented. light of the published scientific evidence, the surgeons who took part showed to have a notable level of information on the most effective diagnostic tests, although, it should be pointed out that there was a lack of confidence in the possibility of ruling out an infection when the erythrocyte sedimentation rate and the C-reactive protein were within normal values, which have been demonstrated in the literature to have a high negative predictive value As regards the treatments to employ in the different situations, the responses of the expert panel were mainly in agreement with the data in the literature. The conclusions of this consensus may help other surgeons when they are faced with a painful knee prosthesis.

The patellar thinning osteotomy in patellofemoral arthritis: four to 18 years' follow-up.

Isolated patellofemoral osteoarthritis can be a disabling disease. When conservative treatment fails, surgical options can be unpredictable and may be considered too aggressive for middle-aged and active people. We analysed the clinical and radiological results of a new coronal osteotomy involving thinning of the patella in a selected group of patients with isolated patellofemoral osteoarthritis. Since 1991, 31 patients (35 knees) have been treated, of whom 34 were available for follow-up at a mean of 9.1 years. The Knee Society Score, the Patellar score and the Short-form-36 questionnaire were used for clinical evaluation. We also examined the radiological features to confirm bone consolidation and assess the progression of osteoarthritis. A significant improvement in the functional scores and radiological parameters was noted. All patients except one were satisfied with the operation. Radiological progression of the patellofemoral osteoarthritis was slowed but radiological femorotibial osteoarthritis progressed in 23 (65%) cases, with a total knee replacement becoming necessary in four cases without technical problems in resurfacing the patella. We compared the results with other forms of surgical treatment reported in the literature. This treatment offers good clinical and radiological results, presenting an alternative method of managing patellofemoral osteoarthritis.

[Tumor necrosis factor as a biomarker of infection in total knee arthroplasty]. / El factor de necrosis tumoral alpha como biomarcador de infección en las artroplastias totales de rodilla.

BACKGROUND: Thanks to defense mechanisms, organisms have had to adapt themselves to an adverse natural setting that causes acute and chronic stress. This adaptive response that tries to protect the cells against lethal insults uses its own defense systems. MATERIAL AND METHODS: Prospective, observational, descriptive pilot study with analytic components to determine the baseline preoperative TNF levels of 35 patients undergoing total knee arthroplasty due to gonarthrosis. Ten patients with a diagnosis of infected total knee arthroplasty were also included. In order to find differences and possible associations, the Mann-Whitney U test or the Fisher test was used to compare the variables between the non-infected group of patients and the group with the infection complication. RESULTS: We found a statistically significant difference; higher levels of fibrinogen, erythrocyte sedimentation rate, C-reactive protein, TNF-alpha and temperature were found in the infected patients; temperature was not clinically relevant. CONCLUSIONS: In the absence of a diagnostic specificity, the combined determinations of acute phase reactants may be useful to detect the presence and intensity of the inflammatory and infectious processes.

[Utility of 3D computed tomography for the surgical planning of pelvic fractures]. / Utilidad de la tomografía computarizada tridimensional en la planificación quirúrgica de las fracturas de pelvis.

BACKGROUND: To determine the utility of 3D computed tomography for the preoperative planning of pelvic rim fractures assessing possible changes in fracture classification as well as in the surgical indication itself. METHODS: We retrospectively reviewed patients who had undergone surgery for complex pelvic fractures during a 15-month period. The mechanism of injury was recorded and the availability of a multi-slice spiral volumetric CT scan was requested as a preoperative study. RESULTS: Ten cases (58%) were pelvic rim fractures and 7 were acetabular fractures. The mean ISS was 23.82 (9-50), and 82.3% of cases were severe traumas (ISS > 16). After the CT scan was obtained, the initial classification of the fracture was changed in four cases (23.5%), without any changes in the surgical indication. An artifact was detected in the volumetric reconstruction but it did not limit the surgeon's interpretation. CONCLUSION: Tridimensional CT-based modeling is very helpful in the surgical planning of pelvic fractures and is a complement of the plain X-rays.