4,628 research outputs found
Some studies of electrophilic species
The use of crystalline hydrogen peroxide adducts was investigated,
as a convenient source of stable anhydrous
hydrogen peroxide for performing various electrophilic
oxidations. In the presence of Lewis acid catalysts,
hydroxylation of aromatic hydrocarbons was achieved to generally
give a mixture of the expected phenolic products.
The yields and isomer distributions of the products varied
with the different reagents and provided information regarding
the nature of the electrophilic species involved. [Continues.
Glucocorticoid-Induced Osteoporosis – A Disorder of Mesenchymal Stromal Cells?
Glucocorticoids are a class of steroid hormones that are essential to life but cause serious harm in excess. The main clinical features of glucocorticoid excess are due to adverse effects on cells and tissues that arise from a common developmental precursor – the mesenchymal stromal cell (MSC; sometimes referred to as the mesenchymal stem cell). Interestingly glucocorticoids appear essential for the differentiation of cells and tissues that arise from MSCs. High levels of glucocorticoids are used in tissue engineering strategies to enhance the formation of tissues such as bone, cartilage, and muscle. This article discusses the paradox that glucocorticoids both enhance and impair MSC development and function. It will describe how endogenous glucocorticoids are likely to be important in these processes in vivo and will discuss the implications for therapies aimed at reducing the damage associated with the use of therapeutic glucocorticoids
Quantum algorithms for testing Boolean functions
We discuss quantum algorithms, based on the Bernstein-Vazirani algorithm, for
finding which variables a Boolean function depends on. There are 2^n possible
linear Boolean functions of n variables; given a linear Boolean function, the
Bernstein-Vazirani quantum algorithm can deterministically identify which one
of these Boolean functions we are given using just one single function query.
The same quantum algorithm can also be used to learn which input variables
other types of Boolean functions depend on, with a success probability that
depends on the form of the Boolean function that is tested, but does not depend
on the total number of input variables. We also outline a procedure to futher
amplify the success probability, based on another quantum algorithm, the Grover
search
Successful Treatment of Radiation-Induced Colitis and Enteritis with Hyperbaric Oxygen Therapy
Introduction
Previously irradiated tissue is characterized by changes including decreased vascularity, impaired cellular proliferation, and local hypoxia consistent with fibroblastic atrophy which can persist long after radiation therapy. Hyperbaric oxygen therapy has been shown to be beneficial in the treatment of complications arising from these late effects of radiation on normal tissue through enhancing fibroblast proliferation, collagen maturation, stem cell recruitment, and angiogenesis.
Methods
We report on three patients with debilitating radiation enterocolitis causing issues including recurrent bowel obstruction, anorexia requiring total parenteral nutrition, pain, diarrhea, fecal incontinence, dehydration, and malnutrition.
Results
In all three cases marked improvement was the outcome with hyperbaric treatment.
Conclusion
Hyperbaric oxygen therapy should be routinely considered in the treatment of radiation-induced enteritis or colitis
Successful Asfotase Alfa Treatment in an Adult Dialysis Patient With Childhood-Onset Hypophosphatasia
Hypophosphatasia is an inherited disease characterized by reduced alkaline
phosphatase activity, extracellular accumulation of inorganic pyrophosphate,
and impaired bone mineralization. Asfotase alfa (AA) is a recombinant human
alkaline phosphatase therapy approved for treatment of pediatric-onset
hypophosphatasia. Studies show promising outcome in AA-treated children with
hypophosphatasia; however, data on adults with pediatric-onset
hypophosphatasia are scarce. We report on a 59-year-old woman with childhood-
onset hypophosphatasia and a history of multiple fractures and orthopedic
procedures. Owing to renal failure (histological diagnosis: focal segmental
glomerulosclerosis), hemodialysis was started in 2013. By the end of 2015, the
patient was unable to walk, could only stand for 30 seconds, and was
completely dependent on help for activities of daily living. After 13 months
of AA therapy, the patient showed a dramatic increase in quality of life
(increased mobility), reduction in pain medication, and a significant
improvement in bone mineralization throughout the skeleton, including
consolidation of existing fractures and no occurrence of new fractures. This
case report demonstrates a relevant therapeutic success of AA treatment in an
adult hemodialysis patient with childhood onset of hypophosphatasia
Natural product libraries: Assembly, maintenance, and screening
This review discusses successful strategies and potential pitfalls to assembling a natural product-based library suitable for high-throughput screening. Specific extraction methods for plants, microorganisms, and marine invertebrates are detailed, along with methods for generating a fractionated sub-library. The best methods to store, maintain and prepare the library for screening are addressed, as well as recommendations on how to develop a robust high-throughput assay. Finally, the logistics of moving from an assay hit to pure bioactive compound are discussed
Prismatine: Revalidation for Boron-Rich Compositions in the Kornerupine Group
Kornerupine and prismatine were introduced independently by Lorenzen in 1884 (but published in 1886 and 1893) and by Sauer in 1886, respectively. Ussing (1889) showed that the two minerals were sufficiently close crystallographically and chemically to be regarded as one species. However, recent analyses of boron using the ion microprobe and crystal structure refinement, indicate that the boron content of one tetrahedral site in kornerupine ranges from 0 to 1. Kornerupine and prismatine, from their respective type localities of Fiskenaesset, Greenland and Waldheim, Germany, are distinct minerals, members of an isomorphic series differing in boron content. For this reason, we re-introduce Sauer\u27s name prismatine for kornerupines with B \u3e 0.5 atoms per formula unit (p.f.u.) of 22(O,OH,F), and restrict the name kornerupine sensu stricto to kornerupines with B \u3c 0.5 p.f.u. Kornerupine sensu lato is an appropriate group name for kornerupine of unknown boron content. Kornerupine sensu stricto and prismatine from the type localities differ also in Fe2+/Mg ratio, Si - (Mg + Fe2+ + Mn) content, Al content, F content, colour, density, cell parameters, and paragenesis. Both minerals formed under granulite-facies conditions with sapphirine and phlogopite, but kornerupine sensu stricto is associated with anorthite and homblende or gedrite, whereas prismatine is found with oligoclase (An9-13), sillimanite, garnet, and/or tourmaline. Occurrences at other localities suggest that increasing boron content extends the stability range of prismatine relative to that of kornerupine sensu stricto
Recovery From Monocular Deprivation Using Binocular Deprivation: Experimental Observations and Theoretical Analysis
Ocular dominance (OD) plasticity is a robust paradigm for examining the functional consequences of synaptic plasticity. Previous experimental and theoretical results have shown that OD plasticity can be accounted for by known synaptic plasticity mechanisms, using the assumption that deprivation by lid suture eliminates spatial structure in the deprived channel. Here we show that in the mouse, recovery from monocular lid suture can be obtained by subsequent binocular lid suture but not by dark rearing. This poses a significant challenge to previous theoretical results. We therefore performed simulations with a natural input environment appropriate for mouse visual cortex. In contrast to previous work we assume that lid suture causes degradation but not elimination of spatial structure, whereas dark rearing produces elimination of spatial structure. We present experimental evidence that supports this assumption, measuring responses through sutured lids in the mouse. The change in assumptions about the input environment is sufficient to account for new experimental observations, while still accounting for previous experimental results
Life expectancy of persons receiving combination antiretroviral therapy in low-income countries: a cohort analysis from Uganda
Little is known about the effect of combination antiretroviral therapy (cART) on life expectancy in sub-Saharan Africa
Commercial Parts Technology Qualification Processes
Many high-reliability systems, including space systems, use selected commercial parts (including Plastic Encapsulated Microelectronics or PEMs) for unique functionality, small size, low weight, high mechanical shock resistance, and other factors. Predominantly this usage is subjected to certain 100% tests (typically called screens) and certain destructive tests usually (but not always) performed on the flight lot (typically called qualification tests). Frequently used approaches include those documented in EEE-INST-002 and JPL DocID62212 (which are sometimes modified by the particular aerospace space systems manufacturer). In this study, approaches from these documents and several space systems manufacturers are compared to approaches from a launch systems manufacturer (SpaceX), an implantable medical electronics manufacturer (Medtronics), and a high-reliability transport system process (automotive systems). In the conclusions section, these processes are outlined for all of these cases and presented in tabular form. Then some simple comparisons are made. In this introduction section, the PEM technology qualification process is described, as documented in EEE-INST-002 (written by the Goddard Space Flight Center, GSFC), as well as the somewhat modified approach employed at the Jet Propulsion Laboratory (JPL). Approaches used at several major NASA contractors are also describe
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