Synthesis of Nucleoside-like Molecules from a Pyrolysis Product of Cellulose and Their Computational Prediction as Potential SARS-CoV-2 RNA-Dependent RNA Polymerase Inhibitors

(1R,5S)-1-Hydroxy-3,6-dioxa-bicyclo[3.2.1]octan-2-one, available by an efficient catalytic pyrolysis of cellulose, has been applied as a chiral building block in the synthesis of seven new nucleoside analogues, with structural modifications on the nucleobase moiety and on the carboxyl- derived unit. The inverted configuration by Mitsunobu reaction used in their synthesis was verified by 2D-NOESY correlations, supported by the optimized structure employing the DFT methods. An in silico screening of these compounds as inhibitors of SARS-CoV-2 RNA-dependent RNA polymerase has been carried out in comparison with both remdesivir, a mono-phosphoramidate prodrug recently approved for COVID-19 treatment, and its ribonucleoside metabolite GS-441524. Drug-likeness prediction and data by docking calculation indicated compound 6 [=(3S,5S)-methyl 5-(hydroxymethyl)-3-(6-(4-methylpiperazin-1-yl)-9H-purin-9-yl)tetrahydrofuran-3-carboxylate] as the best candidate. Furthermore, molecular dynamics simulation showed a stable interaction of structure 6 in RNA-dependent RNA polymerase (RdRp) complex and a lower average atomic fluctuation than GS-441524, suggesting a well accommodation in the RdRp binding pocket.     

Predictability of high-performance spindles using a complete thermo-elastohydrodynamic lubrication (TEHD) solution

Spindles experience problems related to increased power and velocity, and can have very high power consumption. The work reported here is aimed at improving design methods for high-performance spindles and machine-tool bearings, and is aimed at determining the influence, of the oil quantity supplying the contact, on power consumption and on contact temperature. A finite element program, TACT, can efficiently predict power loss and the thermal state of machine-tool bearings, and the remaining unknown in these thermo-piezo-viscous-elastic (TPVE) calculations is inlet oil film height. The authors address this problem and, within the context of this work, develop a high-speed ISO 50 spindle which has a thin-wall bearing housing, and is ‚thermally tuned‚, so avoiding thermal instability, while the preload stays constant. Its experimentally determined power consumption values agree well with the TPVE prediction for an assumed inlet film height of 0.5 μm.     

Relationship of In Vitro Toxicity of Technetium-99m to Subcellular Localisation and Absorbed Dose

Auger electron-emitters increasingly attract attention as potential radionuclides for molecular radionuclide therapy in oncology. The radionuclide technetium-99m is widely used for imaging; however, its potential as a therapeutic radionuclide has not yet been fully assessed. We used MDA-MB-231 breast cancer cells engineered to express the human sodium iodide symporter-green fluorescent protein fusion reporter (hNIS-GFP; MDA-MB-231.hNIS-GFP) as a model for controlled cellular radionuclide uptake. Uptake, efflux, and subcellular location of the NIS radiotracer [^99mTc]TcO₄⁻ were characterised to calculate the nuclear-absorbed dose using Medical Internal Radiation Dose formalism. Radiotoxicity was determined using clonogenic and γ-H2AX assays. The daughter radionuclide technetium-99 or external beam irradiation therapy (EBRT) served as controls. [^99mTc]TcO₄⁻ in vivo biodistribution in MDA-MB-231.hNIS-GFP tumour-bearing mice was determined by imaging and complemented by ex vivo tissue radioactivity analysis. [^99mTc]TcO₄⁻ resulted in substantial DNA damage and reduction in the survival fraction (SF) following 24 h incubation in hNIS-expressing cells only. We found that 24,430 decays/cell (30 mBq/cell) were required to achieve SF_0.37 (95%-confidence interval = [SF_0.31; SF_0.43]). Different approaches for determining the subcellular localisation of [^99mTc]TcO₄⁻ led to SF_0.37 nuclear-absorbed doses ranging from 0.33 to 11.7 Gy. In comparison, EBRT of MDA-MB-231.hNIS-GFP cells resulted in an SF_0.37 of 2.59 Gy. In vivo retention of [^99mTc]TcO₄⁻ after 24 h remained high at 28.0% ± 4.5% of the administered activity/gram tissue in MDA-MB-231.hNIS-GFP tumours. [^99mTc]TcO₄⁻ caused DNA damage and reduced clonogenicity in this model, but only when the radioisotope was taken up into the cells. This data guides the safe use of technetium-99m during imaging and potential future therapeutic applications.     

The design of an animal PET: flexible geometry for achievingoptimal spatial resolution or high sensitivity

Presents the design of a positron emission tomograph (PET) with flexible geometry dedicated to in vivo studies of small animals (TierPET). The scanner uses two pairs of detectors. Each detector consists of 400 small individual yttrium aluminum perovskite (YAP) scintillator crystals of dimensions 2×2×15 mm³, optically isolated and glued together, which are coupled to position-sensitive photomultiplier tubes (PSPMTs). The detector modules can be moved in a radial direction so that the detector-to-detector spacing can be varied. Special hardware has been built for coincidence detection, position detection, and real-time data acquisition, which is performed by a PC. The single-event data are transferred to workstations where the radioactivity distribution is reconstructed. The dimensions of the crystals and the detector layout are the result of extensive simulations which are described in this report, taking into account sensitivity, spatial resolution and additional parameters like parallax error or scatter effects. For the three-dimensional (3-D) reconstruction a genuine 3-D expectation-maximization (EM)-algorithm which can include the characteristics of the detector system has been implemented. The reconstruction software is flexible and matches the different detector configurations. The main advantage of the proposed animal PET scanner is its high flexibility, allowing the realization of various detector-system configurations. By changing the detector-to-detector spacing, the system is capable of either providing good spatial resolution or high sensitivity for dynamic studies of pharmacokinetics     

Renal Dopamine Receptors,Oxidative Stress,and Hypertension

Dopamine, which is synthesized in the kidney, independent of renal nerves, plays an important role in the regulation of fluid and electrolyte balance and systemic blood pressure. Lack of any of the five dopamine receptor subtypes (D1R, D2R, D3R, D4R, and D5R) results in hypertension. D1R, D2R, and D5R have been reported to be important in the maintenance of a normal redox balance. In the kidney, the antioxidant effects of these receptors are caused by direct and indirect inhibition of pro-oxidant enzymes, specifically, nicotinamide adenine dinucleotide phosphate, reduced form (NADPH) oxidase, and stimulation of anti-oxidant enzymes, which can also indirectly inhibit NADPH oxidase activity. Thus, stimulation of the D2R increases the expression of endogenous anti-oxidants, such as Parkinson protein 7 (PARK7 or DJ-1), paraoxonase 2 (PON2), and heme oxygenase 2 (HO-2), all of which can inhibit NADPH oxidase activity. The D5R decreases NADPH oxidase activity, via the inhibition of phospholipase D2, and increases the expression of HO-1, another antioxidant. D1R inhibits NADPH oxidase activity via protein kinase A and protein kinase C cross-talk. In this review, we provide an overview of the protective roles of a specific dopamine receptor subtype on renal oxidative stress, the different mechanisms involved in this effect, and the role of oxidative stress and impairment of dopamine receptor function in the hypertension that arises from the genetic ablation of a specific dopamine receptor gene in mice.     

Review and Restore for Case-Base Maintenance

Case-base maintenance is one of the most important issues for current research in case-based reasoning (CBR). In this article we propose an extended six-step CBR cycle and discuss its two additional steps as part of the maintenance phase of the CBR process. The review step covers assessment and monitoring of the knowledge containers, whereas the restore step actually modifies the contents of the containers according to recommendations resulting from the review step in order to keep the knowledge containers in a usable state. Here we focus our attention on the case base. For the review step, we define several quality measures based on different case and case-base properties that describe specific characteristics of the case base such as correctness, consistency, uniqueness, minimality, and incoherence. Then we use these measures to realize monitoring capabilities for the case-base container that indicate when the restore step is necessary. Finally, we also describe several methods for modifications of the case base in the restore step and their relation to the review step. An initial experimental evaluation shows the appropriateness of the proposed concepts and methods before we conclude the article with a discussion of related work and an outline of future directions to extend these aspects of maintenance in CBR.     

Nitric oxide-mediated protein modification in cardiovascular physiology and pathology

Nitric oxide (NO) is a key regulator of cardiovascular functions including the control of vascular tone, anti-inflammatory properties of the endothelium, cardiac contractility, and thrombocyte activation and aggregation. Numerous experimental data support the view that NO not only acts via cyclic guanosine monophosphate (cGMP)-dependent mechanisms but also modulates protein function by nitrosation, nitrosylation, glutathiolation, and nitration, respectively. To understand how NO regulates all of these diverse biological processes on the molecular level a comprehensive assessment of NO-mediated cGMP-dependent and independent targets is required. Novel proteomic approaches allow the simultaneous identification of large quantities of proteins modified in an NO-dependent manner and thereby will considerably deepen our understanding of the role NO plays in cardiovascular physiology and pathophysiology.     

Evidence for the combined participation of a C10 and a C15 precursor in the biosynthesis of moenocinol, the lipid part of the moenomycin antibiotics

Upon feeding of [2-(13)C,4-(2)H]-1-deoxy-D-xylulose to Streptomyces ghanaensis, the deuterium label was retained exclusively at positions C-7 and C-17 in the moenocinol part of the moenomycin antibiotics. This result vindicates the hypothesis that the C(25) structure of moenocinol is assembled from a C(10) and a C(15) precursor, each of which requires for its formation the involvement of a dimethylallyl diphosphate starter unit.     

Effect of inorganic and organic bioactive signals decoration on the biological performance of chitosan scaffolds for bone tissue engineering

The present work is focused on the design of a bioactive chitosan-based scaffold functionalized with organic and inorganic signals to provide the biochemical cues for promoting stem cell osteogenic commitment. The first approach is based on the use of a sequence of 20 amino acids corresponding to a 68–87 sequence in knuckle epitope of BMP-2 that was coupled covalently to the carboxyl group of chitosan scaffold. Meanwhile, the second approach is based on the biomimetic treatment, which allows the formation of hydroxyapatite nuclei on the scaffold surface. Both scaffolds bioactivated with organic and inorganic signals induce higher expression of an early marker of osteogenic differentiation (ALP) than the neat scaffolds after 3 days of cell culture. However, scaffolds decorated with BMP-mimicking peptide show higher values of ALP than the biomineralized one. Nevertheless, the biomineralized scaffolds showed better cellular behaviour than neat scaffolds, demonstrating the good effect of hydroxyapatite deposits on hMSC osteogenic differentiation. At long incubation time no significant difference among the biomineralized and BMP-activated scaffolds was observed. Furthermore, the highest level of Osteocalcin expression (OCN) was observed for scaffold with BMP2 mimic-peptide at day 21. The overall results showed that the presence of bioactive signals on the scaffold surface allows an osteoinductive effect on hMSC in a basal medium, making the modified chitosan scaffolds a promising candidate for bone tissue regeneration.     

The impact of education and cooking methods on serum phosphate levels in patients on hemodialysis: 1‐year study

Introduction: Control of serum phosphate is important for patients on hemodialysis. The aim of the study was to determine if education based on phosphorus‐reducing techniques in food preparation and thermal processing, and accordingly prepared and applied diets, will lead to better outcomes than a standard education program to improve phosphate control in patients on hemodialysis. Methods: Forty‐seven patients on hemodialysis were divided between an intervention and a control group. All subjects received training about nutrition for hemodialysis patients by trained dietitian. In addition, subjects in the intervention group received additional training in phosphorus‐reducing techniques in food preparation and received two hospital meals prepared using suggested cooking methods to reduce the phosphate content of food during dialysis treatment. Serum phosphate, serum albumin, and anthropometric parameters were measured, while nPCR was calculated, at the baseline and during the 1‐year study. Findings: No differences in serum phosphate levels were observed between intervention (1.68 mmol/L [1.48–2.03]) and control group (1.88 mmol/L [1.57–2.2]) at baseline (P = 0.130). Although not statistically significant between groups the mean reduction was more apparent in the intervention group (?0.3 mmol/L (?0.4 to 0.1) vs. ?0.2 (?0.5 to 0.1)), and lead to significantly reduction of phosphate binder therapy. During the study, the nPCR and anthropometric status of the patients did not change significantly. Discussion: Providing additional education to hemodialysis patients on the specific cooking methods and accordingly prepared meals may decrease serum phosphate levels without significantly affecting nutritional status which may be useful in helping to prevent and treat hyperphosphatemia.