SciCombinator

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Concept: Compression

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Abstract A promising glipizide formulation comprising compression of four-layer coated beads into tablets was prepared. The tablet offered the advantages of: a two-hour lag time before drug release, retaining sustained release characteristics and providing approximately zero-order drug release. Drug release was nearly independent of paddle speeds of 50 and 100 rpm releasing 80% over 14 h similar to the commercial glipizide osmotic pump tablet during dissolution testing while keeping the benefits of multiparticular dosage forms. The tablets contain beads with four layers: (1) the innermost layer consists of 2.5 g glipizide and 3.75 g solid ethylcellulose (Surelease®) coated onto 71.25 g of sugar beads; (2) next a hardening layer of 5 g of hypromellose; (3) the controlled release layer of 7.5 g of Surelease®:lactose at a solids ratio of 100:7 and (4) an outermost layer of 20 g of lactose:sodium starch glycolate (Explotab®) at a 2:1 ratio. Then, beads were compressed into tablets containing 11 mg of glipizide using 1500 lbs of compression pressure. The dissolution test similarity factor (f(2)) was above 50 for all test conditions for formulation F13 and Glucotrol® with a high of 69.9. The two Surelease® layers both aid controlling drug release, with the Surelease®-drug layer affecting drug release to a greater extent.

Concepts: Pharmacology, Pharmaceutical formulation, Excipient, Dosage forms, Compression

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Torsional nystagmus was noted in a patient with hypothalamic hamartoma. Magnetic resonance imaging revealed an exophytic hypothalamic mass extending into the pre-pontine cistern and abutting ventral mesencephalon. The quickphase of the torsional nystagmus was directed towards the left side, ipsilateral to the side of compression by the hamartoma. Ipsi-lesionally directed pure torsional nystagmus in this case is attributed to the compressive lesion of ocular motor structures responsible for the neural integration of torsional and vertical eye movements, namely the interstitial nucleus of Cajal. [Published with video sequences].

Concepts: Brain, Spin, Nuclear magnetic resonance, Magnetic resonance imaging, Mesencephalon, Hypothalamic hamartoma, Nucleus, Compression

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Amorphous matrices, composed of sugars, are markedly plasticized by moisture uptake, which results in physical instability. Our previous studies, in the compression pressure range ≤443 MPa, indicated that when a matrix is compressed, the amount of sorbed water at given relative humidities (RHs) decreases, whereas the glass transition temperature (Tg ) remains constant. Herein, the effect of higher compression pressures than those used previously was explored to investigate the feasibility of using compression to improve the physical stability of amorphous sugar matrix against water uptake and subsequent collapse. Amorphous sugar samples were prepared by freeze-drying and then compressed at 0-665 MPa, followed by rehumidification at given RHs. The physical stability of the amorphous sugar sample was evaluated by measuring Tg and crystallization temperature (Tcry ). The amounts of sorbed water, different in the interaction state, were determined using an FTIR technique. It was found that the compression at pressures of ≥443 MPa decreased the amount of sorbed water, which is a major factor in plasticization and crystallization, and thus markedly increased the Tg and Tcry relative to that for the uncompressed sample. Hence, the compression at several hundreds MPa appears to be feasible for improving the physical stability of amorphous sugar matrix. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci.

Concepts: Liquid, Pressure, Glass, Glass transition, Vacuum, Amorphous solid, Physics of glass, Compression

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Introduction: Orally disintegrating tablets (ODTs) have emerged as one of the novel solid oral dosage forms with a potential to deliver a wide range of drug candidates to both paediatric and geriatric patient populations. Of the plethora of available technologies, compression of excipients offers a cost-effective and translatable methodology for the manufacture of ODTs. Areas covered: The review is a modest endeavour from the authors to assemble literature published over the last couple of decades on formulation development of compressed ODT. It describes the main ODT excipients used since the introduction of this dosage form in the 1990s and explores the switch from cellulose-based excipients towards sugar/polyols. Furthermore, it unfolds the key properties of ODT fillers, binders and disintegrants with an emphasis on their advantages and drawbacks. The review also provides a critical assessment of the various strategies employed for performance enhancement of compressed ODT with a focus on the underlying mechanisms for fast disintegration and acceptable mechanical strength. Expert opinion: Recent increase in the total number of compression-based technologies for ODT development promises to reduce the manufacturing cost of this dosage form in the future. However, some of the developed methods may affect the stability of tablets due to susceptibility to moisture, collapse of pores or the generation of less stable polymorphs which require rigorous testing prior to commercialization.

Concepts: Pharmacology, Novel, Strength of materials, Tablet, Excipient, Dosage forms, Compression, Dosage form

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The aim of this paper was to conduct a systematic review of the published literatures comparing the use of mechanical chest compression device and manual chest compression during cardiac arrest (CA) with respect to short-term survival outcomes and neurological function.

Concepts: Cardiac arrest, Asystole, Academic publishing, Writing, Literature, Publishing, Compression

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AIM: : Outcomes from out-of-hospital cardiac arrest (OHCA) may improve if rescuers perform chest compressions (CCs) deeper than the previous recommendation of 38-51mm and consistent with the 2010 AHA Guideline recommendation of at least 51mm. The aim of this study was to assess the relationship between CC depth and OHCA survival.

Concepts: Heart, Cardiac arrest, Cardiopulmonary resuscitation, Asystole, Data compression, Compression

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The aim of this study was to assess the quality of chest compressions performed by inexperienced rescuers using three different techniques: two-hand, right one-hand, and left one-hand.

Concepts: Cardiac arrest, Asystole, Compression

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The most effective genomic data compression methods either assemble reads into contigs, or replace them with their alignment positions on a reference genome. Such methods require significant computational resources, but faster alternatives that avoid using explicit or de novo-constructed references fail to match their performance. Here, we introduce a new reference-free compressed representation for genomic data based on light de novo assembly of reads, where each read is represented as a node in a (compact) trie. We show how to efficiently build such tries to compactly represent reads and demonstrate that among all methods using this representation (including all de novo assembly based methods), our method achieves the shortest possible output. We also provide an lower bound on the compression rate achievable on uniformly sampled genomic read data, which is approximated by our method well. Our method significantly improves the compression performance of alternatives without compromising speed.

Concepts: Genome, Assembly language, Computational genomics, Data compression, Reference, Compression, Computational resource, Trie

1

The surrounding microenvironment limits tumour expansion, imposing a compressive stress on the tumour, but little is known how pressure propagates inside the tumour. Here we present non-destructive cell-like microsensors to locally quantify mechanical stress distribution in three-dimensional tissue. Our sensors are polyacrylamide microbeads of well-defined elasticity, size and surface coating to enable internalization within the cellular environment. By isotropically compressing multicellular spheroids (MCS), which are spherical aggregates of cells mimicking a tumour, we show that the pressure is transmitted in a non-trivial manner inside the MCS, with a pressure rise towards the core. This observed pressure profile is explained by the anisotropic arrangement of cells and our results suggest that such anisotropy alone is sufficient to explain the pressure rise inside MCS composed of a single cell type. Furthermore, such pressure distribution suggests a direct link between increased mechanical stress and previously observed lack of proliferation within the spheroids core.

Concepts: Scientific method, Cell, Cellular differentiation, Materials science, Stress, Elasticity, Linear elasticity, Compression

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Refractory high-entropy alloys (HEAs) are a class of emerging multi-component alloys, showing superior mechanical properties at elevated temperatures and being technologically interesting. However, they are generally brittle at room temperature, fail by cracking at low compressive strains and suffer from limited formability. Here we report a strategy for the fabrication of refractory HEA thin films and small-sized pillars that consist of strongly textured, columnar and nanometre-sized grains. Such HEA pillars exhibit extraordinarily high yield strengths of ∼10 GPa-among the highest reported strengths in micro-/nano-pillar compression and one order of magnitude higher than that of its bulk form-and their ductility is considerably improved (compressive plastic strains over 30%). Additionally, we demonstrate that such HEA films show substantially enhanced stability for high-temperature, long-duration conditions (at 1,100 °C for 3 days). Small-scale HEAs combining these properties represent a new class of materials in small-dimension devices potentially for high-stress and high-temperature applications.

Concepts: Density, Temperature, Report, Thermodynamics, Silver, Steel, Compression, Ductility