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Least Fourfold (least + fourfold)

Distribution by Scientific Domains

Life Sciences	50%

Selected Abstracts

The nonconserved N-terminus of protein phosphatase 2B confers its properties to protein phosphatase 1

IUBMB LIFE, Issue 2 2009
Xiu-Jie Xie
Abstract The protein phosphatase 1 catalytic subunit (PP1c) and the protein phosphatase 2B (PP2B or calcineurin) catalytic subunit (CNA) contain nonconserved N-terminal regions followed by conserved phosphatase cores. To examine the role of the N-termini of these two phosphatases, we substituted the residues 1,8 of PP1c with residues 1,42 of CNA, which is designated CNA(1-42)-PP1(9-330). The activities of CNA(1-42)-PP1(9-330) were similar to those of PP2B and different from those of PP1. The chimera was at least fourfold less sensitive to inhibition by okadaic acid, but was stimulated by nickel ions and chlorogenic acid, characteristics of PP2B not of PP1. These observations suggest that the N-terminus of CNA shifts the properties of PP1 toward those of PP2B. Our findings provide evidence that the nonconserved N-terminus of PP2B not only functions as important regulatory domain but also confers itself particular characteristics. This region may be targeted for regulation of PP2B activities in vivo. © 2008 IUBMB IUBMB Life, 61(2): 178,183, 2009 [source]

High-Cot sequence analysis of the maize genome

THE PLANT JOURNAL, Issue 2 2003
Yinan Yuan
Summary Higher eukaryotic genomes, including those from plants, contain large amounts of repetitive DNA that complicate genome analysis. We have developed a technique based on DNA renaturation which normalizes repetitive DNA, and thereby allows a more efficient outcome for full genome shotgun sequencing. The data indicate that sequencing the unrenatured outcome of a Cot experiment, otherwise known as High-Cot DNA, enriches genic sequences by more than fourfold in maize, from 5% for a random library to more than 20% for a High-Cot library. Using this approach, we predict that gene discovery would be greater than 95% and that the number of sequencing runs required to sequence the full gene space in maize would be at least fourfold lower than that required for full-genome shotgun sequencing. [source]

Alginate,chitosan complex coacervation for cell encapsulation: Effect on mechanical properties and on long-term viability

BIOPOLYMERS, Issue 6 2006
Limor Baruch
Abstract The use of chitosan in complexation with alginate appears to be a promising strategy for cell microencapsulation, due to the biocompatibility of both polymers and the high mechanical properties attributed by the use of chitosan. The present work focuses on the optimization and characterization of the alginate,chitosan system to achieve long-term cell encapsulation. Microcapsules were prepared from four types of chitosan using one- and two-stage encapsulation procedures. The effect of reaction time and pH on long-term cell viability and mechanical properties of the microcapsules was evaluated. Using the single-stage encapsulation procedure led to increase of at least fourfold in viability compared with the two-stage procedure. Among the four types of chitosan, the use of high molecular weight (MW) chitosan glutamate and low MW chitosan chloride provided high viability levels as well as good mechanical properties, i.e., more than 93% intact capsules. The high viability levels were found to be independent of the reaction conditions when using high MW chitosan. However, when using low MW chitosan, better viability levels (195%) were obtained when using a pH of 6 and a reaction time of 30 min. An alginate,chitosan cell encapsulation system was devised to achieve high cell viability levels as well as to improve mechanical properties, thus holding great potential for future clinical application. © 2006 Wiley Periodicals, Inc. Biopolymers 82:570,579, 2006 This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source]

Increased anterior chamber penetration of topical levofloxacin 0.5% after pulsed dosing in cataract patients

ACTA OPHTHALMOLOGICA, Issue 2 2009
Karin Sundelin
Abstract. Purpose:, This study aimed to investigate the rise in aqueous humour (AH) levels of levofloxacin after a specific perioperative pulsed topical drop regimen. Methods:, Thirty patients undergoing phacoemulsification surgery were administered two preoperative drops of levofloxacin 0.5%, 30 mins apart, and three pulsed drops postoperatively, 5 mins apart. Aqueous humour levels of levofloxacin were measured at the start of surgery and from 5 mins to 90 mins after the last postoperative drop. Samples from individual patients were collected at the time of surgery and at one additional sampling interval by aqueous tap, and analysed using a high-performance liquid chromatography assay. Results:, Aqueous humour levels of levofloxacin continued to rise gradually, reaching a mean peak level (Cmax) of 4.4 ,g/ml (± 2.5) at 60 mins after the last postoperative drop was administered. This level exceeded the minimum inhibitory concentration of common ocular pathogens at least fourfold. At 90 mins after the last drop, mean AH levels remained > 3 ,g/ml. Conclusions:, This is the first study to measure AH levels of levofloxacin after postoperative pulsed dosing in humans. Higher AH levels were found than in previously reported studies in which only preoperative drops were given and levels were measured at the time of surgery. Levels of levofloxacin continued to rise for 60 mins after administration of the last postoperative drop, demonstrating that delivery and maintenance of effective antibiotic levels may be achievable with alternative dosing schedules. [source]