Participation of Glutamate-354 of the CP43 Polypeptide in the Ligation of Manganese and the Binding of Substrate Water in Photosystem II

In the current X-ray crystallographic structural models of photosystem II, Glu354 of the CP43 polypeptide is the only amino acid ligand of the oxygen-evolving Mn4Ca cluster that is not provided by the D1 polypeptide. To further explore the influence of this structurally unique residue on the properties of the Mn4Ca cluster, the CP43-E354Q mutant of the cyanobacterium Synechocystis sp. PCC 6803 was characterized with a variety of biophysical and spectroscopic methods, including polarography, EPR, X-ray absorption, FTIR, and mass spectrometry. The kinetics of oxygen release in the mutant were essentially unchanged from those in wild type. In addition, the oxygen flash yields exhibited normal period four oscillations having normal S state parameters, although the yields were lower, correlating with the mutant's lower steady-state rate (approximately 20% compared to wild type). Experiments conducted with H218O showed that the fast and slow phases of substrate water exchange in CP43-E354Q thylakoid membranes were accelerated 8.5- and 1.8-fold, respectively, in the S3 state compared to wild type. Purified oxygen-evolving CP43-E354Q PSII core complexes exhibited a slightly altered S1 state Mn-EXAFS spectrum, a slightly altered S2 state multiline EPR signal, a substantially altered S 2-minus-S1 FTIR difference spectrum, and an unusually long lifetime for the S2 state (>10 h) in a substantial fraction of reaction centers. In contrast, the S2 state Mn-EXAFS spectrum was nearly indistinguishable from that of wild type. The S2-minus-S 1 FTIR difference spectrum showed alterations throughout the amide and carboxylate stretching regions. Global labeling with 15N and specific labeling with l-[1-13C]alanine revealed that the mutation perturbs both amide II and carboxylate stretching modes and shifts the symmetric carboxylate stretching modes of the α-COO- group of D1-Ala344 (the C-terminus of the D1 polypeptide) to higher frequencies by 3-4 cm -1 in both the S1 and S2 states. The EPR and FTIR data implied that 76-82% of CP43-E354Q PSII centers can achieve the S 2 state and that most of these can achieve the S3 state, but no evidence for advancement beyond the S3 state was observed in the FTIR data, at least not in a majority of PSII centers. Although the X-ray absorption and EPR data showed that the CP43-E354Q mutation only subtly perturbs the structure and spin state of the Mn4Ca cluster in the S 2 state, the FTIR and H218O exchange data show that the mutation strongly influences other properties of the Mn4Ca cluster, altering the response of numerous carboxylate and amide groups to the increased positive charge that develops on the cluster during the S1 to S2 transition and weakening the binding of both substrate water molecules (or water-derived ligands), especially the one that exchanges rapidly in the S3 state. The FTIR data provide evidence that CP43-Glu354 coordinates to the Mn4Ca cluster in the S1 state as a bridging ligand between two metal ions but provide no compelling evidence that this residue changes its coordination mode during the S1 to S 2 transition. The H218O exchange data provide evidence that CP43-Glu354 interacts with the Mn ion that ligates the substrate water molecule (or water-derived ligand) that is in rapid exchange in the S 3 state

Editor's choice : European Society for Vascular Surgery (ESVS) 2020 clinical practice guidelines on the management of acute limb ischaemia

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Survival and prognostic factors in patients with stable and unstable spinal bone metastases from solid tumors: a retrospective analysis of 915 cases

Background: Adequate prediction of survival plays an important role in treatment decisions for patients with spinal bone metastases (SBM). Several prognostic factors are already used in daily clinical practice, but factors related to stability of SBM are still unknown. Therefore, we designed this study to identify these prognostic factors. Methods: We retrospectively assessed 915 patients from solid tumors with commonly metastased into the bone treated at our department between January 2000 and January 2012. Lung cancer (NSCLC), breast and renal cancer listed in Table 1 are the most common solid tumors with bone metastasis in this study. Prostate carcinoma was excluded due to osteoblastic SBM with no influence for stability. We calculated overall survival (OS) and bone survival (BS; time between first diagnosis of bone metastases until death) with the Kaplan-Meier method and assessed prognostic factors for BS with the log-rank test and a Cox regression model separately for patients with stable and unstable SBM. Results: Median follow-up was 9.3 months. OS after 6 months, 1, 2, and 5 years was 81, 62, 42, and 25% in patients with stable SBM and 78, 57, 38, and 22% in patients with unstable SBM (p = 0.851). BS was 57, 38, 22, and 5% in the group of stable SBM after 6 months, 1, 2, and 5 years. For patients with unstable SBM BS after 6 months, 1, 2, and 5 years was 59, 39, 19, and 8% (p = 0.755). In multivariate analysis we found male gender (HR = 1.27 [95% CI 1.01–1.60], p = 0.04), Karnofsky performance status (KPS) <80 % (HR = 1.27 [95%CI 1.04–1.55], p = 0.02) and non-small cell lung cancer (NSCLC; HR = 2.77 [95%CI 1.99–3.86], p <0.0001) to be independent prognostic factors for shortened survival in patients with stable SBM. Independent prognostic factors for unstable SBM were age per year (HR = 1.01 [95% CI 1.0–1.02], p = 0.025), multiple SBM (HR = 1.35 [95% CI 1.1–1.65], p = 0.003), and NSCLC (HR = 2.0 [95% CI 1.43–2.80], p &lt; 0.0001). Additionally, not wearing an orthopedic corset (HR = 0.77 [95% CI 0.62–0.96], p = 0.02) was associated with prolonged BS in patients with unstable SBM and in both groups BS was significantly longer in patients without liver metastases (stable SBM: HR = 0.72 [95% CI 0.56–0.92], p = 0.008; unstable SBM: HR = 0.71 [95% CI 0.54–0.92], p = 0.01). Conclusions: Survival was equal for patients with stable and unstable SBM. However, prognostic factors differed in both groups and stability should therefore be considered in treatment decision-making

Isometric muscle training of the spine musculature in patients with spinal bony metastases under radiation therapy

<p/> <p>Background</p> <p>Osseous metastatic involvement of the spinal column affects many patients with a primary tumour disease of all entities. The consequences are pain both at rest and under exertion, impairments in going about day-to-day activities, diminished performance, the risk of pathological fractures, and neurological deficits. Palliative percutaneous radiotherapy is one of the therapeutical options available in this connection. The aim of this explorative study is to investigate the feasibility of muscle-training exercises and to evaluate the progression- and fracture-free survival time and the improvement of bone density, as well as to assess other clinical parameters such as pain, quality of life, and fatigue as secondary endpoints.</p> <p>Methods/Design</p> <p>This study is a prospective, randomized, monocentre, controlled explorative intervention study in the parallel-group design to determine the multidimensional effects of a course of exercises at first under physiotherapeutic instruction and subsequently performed by the patients independently for strengthening the paravertebral muscles of patients with metastases of the vertebral column parallel to their percutaneous radiotherapy. On the days of radiation treatment the patients in the control group shall be given physical treatment in the form of respiratory therapy and the so-called "hot roll". The patients will be randomized into one of the two groups: differentiated muscle training or physiotherapy with thirty patients in each group.</p> <p>Discussion</p> <p>The aim of the study is to evaluate the feasibility of the training programme described here. Progression-free and fracture-free survival, improved response to radiotherapy by means of bone density, and clinical parameters such as pain, quality of life, and fatigue constitute secondary study objectives.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT01409720">NCT01409720</a></p

Phase II study evaluating consolidation whole abdominal intensity-modulated radiotherapy (IMRT) in patients with advanced ovarian cancer stage FIGO III - The OVAR-IMRT-02 Study

<p>Abstract</p> <p>Background</p> <p>The prognosis for patients with advanced FIGO stage III epithelial ovarian cancer remains poor despite the aggressive standard treatment, consisting of maximal cytoreductive surgery and platinum-based chemotherapy. The median time to recurrence is less than 2 years, with a 5-years survival rate of -20-25%. Recurrences of the disease occur mostly intraperitoneally.</p> <p>Ovarian cancer is a radiosensitive tumor, so that the use of whole abdominal radiotherapy (WAR) as a consolidation therapy would appear to be a logical strategy. WAR used to be the standard treatment after surgery before the chemotherapy era; however, it has been almost totally excluded from the treatment of ovarian cancer during the past decade because of its high toxicity. Modern intensity-modulated radiation therapy (IMRT) has the potential of sparing organs at risk like kidneys, liver, and bone marrow while still adequately covering the peritoneal cavity with a homogenous dose.</p> <p>Our previous phase I study showed for the first time the clinical feasibility of intensity-modulated WAR and pointed out promising results concerning treatment tolerance. The current phase-II study succeeds to the phase-I study to further evaluate the toxicity of this new treatment.</p> <p>Methods/design</p> <p>The OVAR-IMRT-02 study is a single-center one arm phase-II trial. Thirty seven patients with optimally debulked ovarian cancer stage FIGO III having a complete remission after chemotherapy will be treated with intensity-modulated WAR as a consolidation therapy.</p> <p>A total dose of 30 Gy in 20 fractions of 1.5 Gy will be applied to the entire peritoneal cavity including the liver surface and the pelvic and para-aortic node regions. Organ at risk are kidneys, liver (except the 1 cm-outer border), heart, vertebral bodies and pelvic bones.</p> <p>Primary endpoint is tolerability; secondary objectives are toxicity, quality of life, progression-free and overall survival.</p> <p>Discussion</p> <p>Intensity-modulated WAR provides a new promising option in the consolidation treatment of ovarian carcinoma in patients with a complete pathologic remission after adjuvant chemotherapy. Further consequent studies will be needed to enable firm conclusions regarding the value of consolidation radiotherapy within the multimodal treatment of advanced ovarian cancer.</p> <p>Trial registration</p> <p>Clinicaltrials.gov: <a href="http://clinicaltrials.gov/ct2/show/NCT01180504">NCT01180504</a></p

iMARS Phase 2

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