Zobrazení zdroje stránky Reecekorsgaard0012

If point-group symmetry has been applied to the map during reconstruction, the asymmetric unit model is refined with the appropriate symmetry constraints.Structure-based drug development suffers from high attrition rates due to the poor activity of lead compounds in cellular and animal models caused by low cell penetrance, off-target binding or changes in the conformation of the target protein in the cellular environment. The latter two effects cause a change in the apparent binding affinity of the compound, which is indirectly assessed by cellular activity assays. To date, direct measurement of the intracellular binding affinity remains a challenging task. In this work, in-cell NMR spectroscopy was applied to measure intracellular dissociation constants in the nanomolar range by means of protein-observed competition binding experiments. Competition binding curves relative to a reference compound could be retrieved either from a series of independent cell samples or from a single real-time NMR bioreactor run. The method was validated using a set of sulfonamide-based inhibitors of human carbonic anhydrase II with known activity in the subnanomolar to submicromolar range. The intracellular affinities were similar to those obtained in vitro, indicating that these compounds selectively bind to the intracellular target. In principle, the approach can be applied to any soluble intracellular target that gives rise to measurable chemical shift changes upon ligand binding.Metalloproteins catalyze a range of reactions, with enhanced chemical functionality due to their metal cofactor. The reaction mechanisms of metalloproteins have been experimentally characterized by spectroscopy, macromolecular crystallography and cryo-electron microscopy. An important caveat in structural studies of metalloproteins remains the artefacts that can be introduced by radiation damage. Photoreduction, radiolysis and ionization deriving from the electromagnetic beam used to probe the structure complicate structural and mechanistic interpretation. Neutron protein diffraction remains the only structural probe that leaves protein samples devoid of radiation damage, even when data are collected at room temperature. Additionally, neutron protein crystallography provides information on the positions of light atoms such as hydrogen and deuterium, allowing the characterization of protonation states and hydrogen-bonding networks. Neutron protein crystallography has further been used in conjunction with experimental and computational techniques to gain insight into the structures and reaction mechanisms of several transition-state metal oxidoreductases with iron, copper and manganese cofactors. Here, the contribution of neutron protein crystallography towards elucidating the reaction mechanism of metalloproteins is reviewed.All biological processes rely on the formation of protein-ligand, protein-peptide and protein-protein complexes. Studying the affinity, kinetics and thermodynamics of binding between these pairs is critical for understanding basic cellular mechanisms. Many different technologies have been designed for probing interactions between biomolecules, each based on measuring different signals (fluorescence, heat, thermophoresis, scattering and interference, among others). Evaluation of the data from binding experiments and their fitting is an essential step towards the quantification of binding affinities. Here, user-friendly online tools to analyze biophysical data from steady-state fluorescence spectroscopy, microscale thermophoresis and differential scanning fluorimetry experiments are presented. The modules of the data-analysis platform (https//spc.embl-hamburg.de/) contain classical thermodynamic models and clear user guidelines for the determination of equilibrium dissociation constants (Kd) and thermal unfolding parameters such as melting temperatures (Tm).Time-resolved cryo-electron microscopy (TrEM) allows the study of proteins under non-equilibrium conditions on the millisecond timescale, permitting the analysis of large-scale conformational changes or assembly and disassembly processes. However, the technique is developing and there have been few comparisons with other biochemical kinetic studies. Using current methods, the shortest time delay is on the millisecond timescale (∼5-10 ms), given by the delay between sample application and vitrification, and generating longer time points requires additional approaches such as using a longer delay line between the mixing element and nozzle, or an incubation step on the grid. To compare approaches, the reaction of ATP with the skeletal actomyosin S1 complex was followed on grids prepared with a 7-700 ms delay between mixing and vitrification. Classification of the cryo-EM data allows kinetic information to be derived which agrees with previous biochemical measurements, showing fast dissociation, low occupancy during steady-state hydrolysis and rebinding once ATP has been hydrolysed. However, this rebinding effect is much less pronounced when on-grid mixing is used and may be influenced by interactions with the air-water interface. Moreover, in-flow mixing results in a broader distribution of reaction times due to the range of velocities in a laminar flow profile (temporal spread), especially for longer time delays. This work shows the potential of TrEM, but also highlights challenges and opportunities for further development.Careful selection of photocaging approaches is critical to achieve fast and well synchronized reaction initiation and perform successful time-resolved structural biology experiments. This review summarizes the best characterized and most relevant photocaging groups previously described in the literature. It also provides a walkthrough of the essential factors to consider in designing a suitable photocaged molecule to address specific biological questions, focusing on photocaging groups with well characterized spectroscopic properties. The relationships between decay rates (k in s-1), quantum yields (ϕ) and molar extinction coefficients (ϵmax in M-1 cm-1) are highlighted for different groups. The effects of the nature of the photocaged group on these properties is also discussed. Four main photocaging scaffolds are presented in detail, o-nitrobenzyls, p-hydroxyphenyls, coumarinyls and nitrodibenzofuranyls, along with three examples of the use of this technology. Furthermore, a subset of specialty photocages are highlighted photoacids, molecular photoswitches and metal-containing photocages. These extend the range of photocaging approaches by, for example, controlling pH or generating conformationally locked molecules.<br /><br /> Prostatic carcinoma withsignet ring cells is a very rare histopathological entity, withfew infected cases in the literature, for which there is nomanagement protocol. DESCRIPTION OF CASES Two patients are presented,one 46 years old and the other 76 years old, the firstdebuts with a decompensated picture of urinary and intestinalobstruction, and the second presents a torpid evolutionof his disease with progression from stage I to III in threemonths. DISCUSSION Mucosacretory prostate tumors have theirown morphohistological and immunohistochemical characteristics,which differentiate them from classic adenocarcinomas. CONCLUSIONS Prostatic carcinoma with signet ring cellsis an entity that must be borne in mind, especially in patientswith rapid progression of their disease.<br /><br />Prostatic carcinoma withsignet ring cells is a very rare histopathological entity, withfew infected cases in the literature, for which there is nomanagement protocol. DESCRIPTION OF CASES Two patients are presented,one 46 years old and the other 76 years old, the firstdebuts with a decompensated picture of urinary and intestinalobstruction, and the second presents a torpid evolutionof his disease with progression from stage I to III in threemonths. DISCUSSION Mucosacretory prostate tumors have theirown morphohistological and immunohistochemical characteristics,which differentiate them from classic adenocarcinomas. CONCLUSIONS Prostatic carcinoma with signet ring cellsis an entity that must be borne in mind, especially in patientswith rapid progression of their disease.<br /><br /> To assess the metastasic prostatecancer in the differenctial diagnosis of mediastinal masses.METHODS To report a case.RESULTS We present the case of a 78-year-old male patientwith a diagnosis of prostate cancer with a mediastinalmass compatible with prostate metastasis.CONCLUSION Mediastinum is a very rare site for prostatecancer metastasis, but it must be considered in thedifferential diagnosis of mediastinal masses. Treatment isthe usual for metastatic prostate cancer.<br /><br />To assess the metastasic prostatecancer in the differenctial diagnosis of mediastinal masses. METHODS To report a case. RESULTS We present the case of a 78-year-old male patientwith a diagnosis of prostate cancer with a mediastinalmass compatible with prostate metastasis. CONCLUSION Mediastinum is a very rare site for prostatecancer metastasis, but it must be considered in thedifferential diagnosis of mediastinal masses. Treatment isthe usual for metastatic prostate cancer.<br /><br /> Parastomal hernia in patientswith ileal urinary diversion is insufficiently described in theliterature, and among its complications, the presence ofurinary obstruction is not usually reported.METHODS We present a 74-year-old male with a Brickertype urinary diversion. He presented urinary infections withCT scan showing hydronephrosis with obstruction of theileal conduit probably related to a parastomal hernia. [https://www.selleckchem.com/products/Elesclomol.html Selleckchem STA-4783] Thehernia growth runs in parallel to the ureterohydronephrosis,so we performed a hernioplasty to solve the obstruction. CTat 6 months shows no urinary obstruction and no hernia recurrence.No hydronephrosis in the follow-up at 14 months.RESULTS We reviewed the literature and we only foundthree articles that related parastomal hernia in Bricker toureterohydronephrosis, although none of them proved thisrelationship with the correction of the urinary obstructionafter hernia surgery.CONCLUSIONS Parastomal hernia should be consideredin the differential diagnosis of obstructive uropathy in patientswith ileal patientswith ileal urinary diversion.<br /><br /> This study aims to compare infectious complications after a prostate biopsy in patients with or without chronic idiopathic constipation (CIC).<br /><br /> Six hundred and sixty-three patients who underwent a transrectal ultrasound-guided biopsy (TRUSBx) of the prostate between 2012 and 2018 were evaluated prospectively. Patients were divided into two groups according to their CIC status and monitored for complications. CIC was defined by the Rome III criteria. Multivariate analysis was performed to assess the risk factors.<br /><br /> Thirty-five patients (5.8%) developed a urinary tract infection (UTI) while sepsis occurred in only three cases (0.5%). CIC was found as a risk factor for infection. Infection occurred in 18.1% of the men with CIC compared to 2.3% of those without CIC (p=0.001). Sepsis occurred in 1.4% of the men with CIC compared to vs 0.2% of those without CIC (p=0.68). In multivariate analysis, CIC (OR of 9.27 and 95% CI 4.40-19.54, p&lt;0.05) and Diabetes Mellitus (OR of 3.11 and 95% CI 1.52-6.36, p=0.002) were associated with an increased risk factor of UTI and sepsis.