793 research outputs found
Network-analysis-guided synthesis of weisaconitine D and liljestrandinine.
General strategies for the chemical synthesis of organic compounds, especially of architecturally complex natural products, are not easily identified. Here we present a method to establish a strategy for such syntheses, which uses network analysis. This approach has led to the identification of a versatile synthetic intermediate that facilitated syntheses of the diterpenoid alkaloids weisaconitine D and liljestrandinine, and the core of gomandonine. We also developed a web-based graphing program that allows network analysis to be easily performed on molecules with complex frameworks. The diterpenoid alkaloids comprise some of the most architecturally complex and functional-group-dense secondary metabolites isolated. Consequently, they present a substantial challenge for chemical synthesis. The synthesis approach described here is a notable departure from other single-target-focused strategies adopted for the syntheses of related structures. Specifically, it affords not only the targeted natural products, but also intermediates and derivatives in the three families of diterpenoid alkaloids (C-18, C-19 and C-20), and so provides a unified synthetic strategy for these natural products. This work validates the utility of network analysis as a starting point for identifying strategies for the syntheses of architecturally complex secondary metabolites
Developing and Testing a Contingency Paradigm of Group Choice in Organizational Buying
Disease classification from capillary electrophoresis: mass spectrometry
We investigate the possibility of using pattern recognition techniques to classify various disease types using data produced by a new form of rapid Mass Spectrometry. The data format has several advantages over other high-throughput technologies and as such could become a useful diagnostic tool. We investigate the binary and multi-class performances obtained using standard classifiers as the number of features is varied and conclude that there is potential in this technique and suggest research directions that would improve performance
Six-minute walking test in children with ESRD: discrimination validity and construct validity
Upper limb disease evolution in exon 53 skipping eligible patients with Duchenne muscular dystrophy
Objective:
To understand the natural disease upper limb progression over 3 years of ambulatory and non-ambulatory patients with Duchenne muscular dystrophy (DMD) using functional assessments and quantitative magnetic resonance imaging (MRI) and to exploratively identify prognostic factors.
Methods:
Forty boys with DMD (22 non-ambulatory and 18 ambulatory) with deletions in dystrophin that make them eligible for exon 53-skipping therapy were included. Clinical assessments, including Brooke score, motor function measure (MFM), hand grip and key pinch strength, and upper limb distal coordination and endurance (MoviPlate), were performed every 6 months and quantitative MRI of fat fraction (FF) and lean muscle cross sectional area (flexor and extensor muscles) were performed yearly.
Results:
In the whole population, there were strong nonlinear correlations between outcome measures. In non-ambulatory patients, annual changes over the course of 3 years were detected with high sensitivity standard response mean (|SRM| â„0.8) for quantitative MRI-based FF, hand grip and key pinch, and MFM. Boys who presented with a FF27% were able to bring a glass to their mouth and retained this ability in the following 3 years. Ambulatory patients with grip strength >35% of predicted value and FF <10% retained ambulation 3 years later.
Interpretation:
We demonstrate that continuous decline in upper limb strength, function, and MRI measured muscle structure can be reliably measured in ambulatory and non-ambulatory boys with DMD with high SRM and strong correlations between outcomes. Our results suggest that a combination of grip strength and FF can be used to predict important motor milestones
Soft systems methodology: a context within a 50-year retrospective of OR/MS
Soft systems methodology (SSM) has been used in the practice of operations research and management science OR/MS) since the early 1970s. In the 1990s, it emerged as a viable academic discipline. Unfortunately, its proponents consider SSM and traditional systems thinking to be mutually exclusive. Despite the differences claimed by SSM proponents between the two, they have been complementary. An extensive sampling of the OR/MS literature over its entire lifetime demonstrates the richness with which the non-SSM literature has been addressing the very same issues as does SSM
Good practices for a literature survey are not followed by authors while preparing scientific manuscripts
The number of citations received by authors in scientific journals has become
a major parameter to assess individual researchers and the journals themselves
through the impact factor. A fair assessment therefore requires that the
criteria for selecting references in a given manuscript should be unbiased with
respect to the authors or the journals cited. In this paper, we advocate that
authors should follow two mandatory principles to select papers (later
reflected in the list of references) while studying the literature for a given
research: i) consider similarity of content with the topics investigated, lest
very related work should be reproduced or ignored; ii) perform a systematic
search over the network of citations including seminal or very related papers.
We use formalisms of complex networks for two datasets of papers from the arXiv
repository to show that neither of these two criteria is fulfilled in practice
Clinical and Molecular Characteristics and Outcome of Cystic Partially Differentiated Nephroblastoma and Cystic Nephroma: A Narrative Review of the Literature
In children presenting with a predominantly cystic renal tumor, the most likely diagnoses
include cystic partially differentiated nephroblastoma (CPDN) and cystic nephroma (CN). Both
entities are rare and limited information on the clinical and molecular characteristics, treatment, and
outcome is available since large cohort studies are lacking. We performed an extensive literature
review, in which we identified 113 CPDN and 167 CN. The median age at presentation for CPDN
and CN was 12 months (range: 3 weeksâ4 years) and 16 months (prenatal diagnosisâ16 years),
respectively. No patients presented with metastatic disease. Bilateral disease occurred in both entities.
Surgery was the main treatment for both. Two/113 CPDN patients and 26/167 CN patients had
previous, concomitant, or subsequent other tumors. Unlike CPDN, CN was strongly associated with
somatic (n = 27/29) and germline (n = 12/12) DICER1-mutations. Four CPDN patients and one CN
patient relapsed. Death was reported in six/103 patients with CPDN and six/118 CN patients, none
directly due to disease. In conclusion, children with CPDN and CN are young, do not present with
metastases, and have an excellent outcome. Awareness of concomitant or subsequent tumors and
genetic testing is important. International registration of cystic renal tumor cohorts is required to
enable a better understanding of clinical and genetic characteristics
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