464 research outputs found
Fluorine-18 fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography scan contributes to the diagnosis and management of brucellar spondylodiskitis
BACKGROUND: Limited data suggest that fluorine-18 fluoro-2-deoxy-D-glucose (F-18 FDG) positron emission tomography combined with computed tomography (PET/CT) scan may be useful for diagnosing infections of the spine. Brucellar spondylodiskitis might be devastating and current imaging techniques lack sensitivity and specificity. The aim of this prospective study was to determine the role of F-18 FDG PET/CT scan in the diagnosis of brucellar spondylodiskitis and in monitoring the efficacy of its treatment. METHODS: Ten consecutive patients with brucellar spondylitis were prospectively evaluated with PET/CT. Baseline evaluation included also magnetic resonance imaging (MRI) of the affected spine, indices of inflammation, the slide agglutination test (SAT), and the standard hematology and biochemistry. All cases were treated with suitable antibiotics until resolution or significant improvement of clinical and radiological (MRI) findings. Upon completion of treatment, they were re-evaluated with follow-up PET/CT scan. The maximum standardized uptake values (SUV) were measured and compared with SAT. RESULTS: In all patients there was an increased F-18 FDG activity in the infected spine region detected by the initial MRI. F-18 FDG PET/CT provided additional information, compared to MRI, in 4 (40%) patients. More specifically it revealed additional spine lesions (in 3 patients), lymphadenitis, arthritis, organomegaly, as well as new paravertebral soft tissue involvement and epidural masses. This additional information had an impact on the duration of treatment in these patients. At the end of treatment all patients had a complete clinical response; 5 patients had positive serology, 6 patients had residual MRI findings, while 9 had a positive PET/CT but with significantly decreased FDG uptake compared to baseline (median 2.6, range 1.4 – 4.4 vs. median 5.5, range 2.8 – 9.4, p = 0.005). During the follow up period (median 12.5 months) no relapses have been observed. No significant association was observed between the SUV and SAT. CONCLUSIONS: Our study suggests that in patients with brucellar spondylodiskitis F-18 FDG PET/CT scan can provide additional information on the spread of the infection, compared to MRI. Successful treatment is associated with a significant decrease in SUVmax values; thus, PET/CT scan may be a complementary method for determining the efficacy of treatment
2,4-Dioxa-λ6-thiatetracyclo[5.3.1.15,9.01,5]dodecane-3,3-dione
The crystal structure of the title compound, C9H12O4S, was determined in order to investigate the effect of the eclipsed O atoms on the bond length of the vicinal quaternary C atoms. The two quaternary C atoms of the noradamantane skeleton and the two O atoms to which they are connected all located essentially in the same plane (maximum deviation = 0.01 Å), resulting in an eclipsed conformation of the C—O bonds. The C—C bond of the quaternary C atoms is 1.581 (3) Å, considerably longer than the other C—C bonds of the molecule due to the stretch of the cage structure
Source of Reality/Causal Capacity: Outside of the Priority Chain?
I will consider two views about the structure of reality: metaphysical foundationalism (all grounded entities are fully grounded in ungrounded entities) and metaphysical infinitism (there are infinite chains of grounding that lack a foundation). Foundationalists motivate their view by appealing to an intuition that there must be a fundamental level that is the source of reality (Schaffer) or causal capacity (Trogdon) of grounded entities because a grounded entity inherits its reality or causal capacity from its ground and there would be a vicious infinite regress otherwise. I will argue that this argument is not successful as the source of reality or causal capacity of an infinite chain can be its cause. For example, this source can be the direct physical cause, the first physical cause or a Prime Mover. A vicious infinite regress is avoided this way too because there is no transference of the same status ad infinitum
Multi-descriptional physicalism, level(s) of being, and the mind-body problem
The main idea of this thesis is multi-descriptional physicalism. According to it, only physical entities are elements of our ontology, and there are different ways to describe them. Higher-level vocabularies (e.g., mental, neurological, biological) truly describe reality. Sentences about higher-level entities are made true by physical entities. Every chapter will develop multi-descriptional physicalism or defend it from objections. In chapter 1, I will propose a new conceptual reductive account that conceptually reduces higher-level entities to physical entities. This conceptual reductive account combines resources from Heil’s truthmaker theory and either a priori physicalism or a posteriori physicalism. In chapter 2, I apply this conceptual reductive account to various debates. Physicalism, the multiple-realisability argument, the prototype theory of concepts, and truthmaker explanations will be discussed. In chapter 3, I will argue that a major aim of metaphysics should be to discover which entities are fundamental and explain why they suffice for the existence of derivative entities. In chapter 4, I will propose a new way to explain why sentences apparently about composite objects are true even though there are no composite objects. It combines resources from Cameron’s truthmaker theory and van Inwagen’s paraphrase strategy. In chapter 5, I will argue that the intuition that the mind and the body are very different does not show that the mind is distinct from the body. This intuition can be explained away by mentioning our dispositions to give non-physical explanations when we are ignorant of physical facts. In chapter 6, I will examine two arguments for the existence of a metaphysically independent level, and I will argue that only a modified version of one of them succeeds. I will argue that methodological principles support the view that there is a metaphysically independent level
HelioTrope: An innovative and efficient prototype for solar power production
The solar energy alternative could provide us with all the energy we need as it exist in vast quantities all around us. We only should be innovative enough in order to improve the efficiency of our systems in capturing and converting solar energy in usable forms of power. By making a case for the solar energy alternative, we identify areas where efficiency can be improved and thereby Solar Energy can become a competitive energy source. This paper suggests an innovative approach to solar energy power production, which is manifested in a prototype given the name HelioTrope. The Heliotrope Solar Energy Production prototype is tested on its' capabilities to efficiently covert solar energy to generation of electricity and other forms of energy for storage or direct use. HelioTrope involves an innovative Stirling engine design and a parabolic concentrating dish with a sun tracking system implementing a control algorithm to maximize the capturing of solar energy. Further, it utilizes a patent developed by the authors where a mechanism is designed for the transmission of reciprocating motion of variable amplitude into unidirectional circular motion. This is employed in our prototype for converting linear reciprocating motion into circular for electricity production, which gives a significant increase in efficiency and reduces maintenance costs. Preliminary calculations indicate that the Heliotrope approach constitutes a competitive solution to solar power production
Tricyclo[3.3.1.03,7]nonane-3,7-diyl bis(methanesulfonate)
The crystal structure of the title compound, C11H18O6S2, was determined to investigate the effect of the eclipsed mesyl groups on the bond length of the vicinal quaternary C atoms. The two quaternary C atoms of the noradamantane skeleton and the two O atoms to which they are connected all located essentially in the same plane [maximum deviation 0.01 Å], resulting in an eclipsing conformation of the C—O bonds. The C—C bond of the quaternary C atoms is 1.597 (3) Å is considerably longer than the other C—C bonds of the molecule
Synthesis and photophysical studies of a low-symmetry tribenzoisothiazoloporphyrazine
A new low-symmetry tetraazaporphyrin has been synthesized and characterized by 1 H NMR, electronic spectroscopies and high resolution mass spectrometry. The photophysical behavior of the newly synthesized low-symmetry zinc tetraazaporphyrin ZnPz 1 has been examined and compared with that of the symmetrical tert-octylphenoxy zinc phthalocyanine ZnPc 2, by using steady-state absorption and fluorescence, cyclic voltammetry, molecular orbital calculation, and femtosecond transient absorption techniques
DNA-induced spatial entrapment of general transcription machinery can stabilize gene expression in a nondividing cell.
Funder: Wellcome TrustAn important characteristic of cell differentiation is its stability. Only rarely do cells or their stem cell progenitors change their differentiation pathway. If they do, it is often accompanied by a malfunction such as cancer. A mechanistic understanding of the stability of differentiated states would allow better prospects of alleviating the malfunctioning. However, such complete information is yet elusive. Earlier experiments performed in Xenopus oocytes to address this question suggest that a cell may maintain its gene expression by prolonged binding of cell type-specific transcription factors. Here, using DNA competition experiments, we show that the stability of gene expression in a nondividing cell could be caused by the local entrapment of part of the general transcription machinery in transcriptionally active regions. Strikingly, we found that transcriptionally active and silent forms of the same DNA template can stably coexist within the same nucleus. Both DNA templates are associated with the gene-specific transcription factor Ascl1, the core factor TBP2, and the polymerase II (Pol-II) ser5 C-terminal domain (CTD) phosphorylated form, while Pol-II ser2 CTD phosphorylation is restricted to the transcriptionally dominant template. We discover that the active and silent DNA forms are physically separated in the oocyte nucleus through partition into liquid-liquid phase-separated condensates. Altogether, our study proposes a mechanism of transcriptional regulation involving a spatial entrapment of general transcription machinery components to stabilize the active form of a gene in a nondividing cell
LED-induced Ru-photoredox Pd-catalyzed C-H arylation of (6-phenylpyridin-2-yl)pyrimidines and heteroaryl counterparts.
N-heterocycles are essential building blocks and scaffolds in medicinal chemistry. A Pd-catalyzed, Ru-photoredox-mediated C-H arylation is applied herein, for converting a series of functionality-inclusive (6-phenylpyridin-2-yl)pyrimidines to single arylated derivatives, using phenyldiazonium tetrafluoroborate as aryl source. This green chemistry-compliant transformation is induced by LED light. The drug-like modular substrates are constructed via combination of Biginelli multi-component condensation and Suzuki C-C cross-coupling, in order to strategically install, adjacent to the Ph-ring intended to undergo C-H arylation, a (6-pyridin-2-yl)pyrimidine that plays the role of a chelating directing moiety for the C-H arylation catalyst. The scope has been demonstrated on a series of 26 substrates, comprising diverse Ph-ring substituents and substitution patterns, as well as with 13 different aryl donors. Substrates in which the Ph-ring (arylation acceptor) was replaced by an electron-rich heteroaryl counterpart (2-/3-thiophene or -benzofuran) have also been examined and found to undergo arylation regioselectively. End-product conformations afford interesting motifs for occupying 3D chemical space, as implied by single-crystal X-ray diffraction, which has allowed the elucidation of six structures of aryl derivatives and one of an unprecedented pyrimidine-pyridine-benzofuran carbopalladated complex, believed to be a C-H activation derivative
Stochastic combinations of actin regulatory proteins are sufficient to drive filopodia formation.
Assemblies of actin and its regulators underlie the dynamic morphology of all eukaryotic cells. To understand how actin regulatory proteins work together to generate actin-rich structures such as filopodia, we analyzed the localization of diverse actin regulators within filopodia in Drosophila embryos and in a complementary in vitro system of filopodia-like structures (FLSs). We found that the composition of the regulatory protein complex where actin is incorporated (the filopodial tip complex) is remarkably heterogeneous both in vivo and in vitro. Our data reveal that different pairs of proteins correlate with each other and with actin bundle length, suggesting the presence of functional subcomplexes. This is consistent with a theoretical framework where three or more redundant subcomplexes join the tip complex stochastically, with any two being sufficient to drive filopodia formation. We provide an explanation for the observed heterogeneity and suggest that a mechanism based on multiple components allows stereotypical filopodial dynamics to arise from diverse upstream signaling pathways.Herchel Smith Fellowship, Funai Foundation scholarship, Austrian Science Fun
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