172,241 research outputs found
Epoxysuccinyl peptide-derived cathepsin B inhibitors: Modulating membrane permeability by conjugation with the C-terminal heptapeptide segment of penetratin
No full textSchaschke N, Deluca D, Assfalg-Machleidt I, Hohneke C, Sommerhoff CP, Machleidt W. Epoxysuccinyl peptide-derived cathepsin B inhibitors: Modulating membrane permeability by conjugation with the C-terminal heptapeptide segment of penetratin. BIOLOGICAL CHEMISTRY. 2002;383(5):849-852
Pilot Study of the Effects of Tai Chi on Elderly Fall Risks
No full textIntroduction. Falls in the elderly are a significant public health concern. Tai Chi has been shown to reduce falls in this population and increase muscle strength, balance, mood, confidence and sleep.Presented at the American Public Health Association 141st Annual Meeting & Exposition, Boston, MA, November 3, 2013 as "Pilot study of the effects of tai chi on elderly fall risks," Amanda Dauten, Kara Klingman, Kyung Jun Min, Emily Schloff, Vishal Shah, MS, Corey Sheahan, Sarah Vossoughi, Kathleen Hall, PhD, Devida Deluca, Philip Trabulsy, MD and Jan K. Carney, MD MPH
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Accelerated polymer biodegradation of risperidone poly(D, L-lactide-co-glycolide) microspheres
No full textThe influence of a tertiary amine, namely risperidone (pKa = 7.9) on the degradation of poly(D, L lactide-co-glycolide) (PLGA) microspheres was elucidated. Risperidone and blank microspheres were fabricated at two lactide/glycolide ratios, 65:35 and 85:15. The microspheres were characterized for drug loading by high-performance liquid chromatography, particle size by laser diffractometry, and surface morphology by scanning electron microscopy. Polymer degradation studies were carried out with drug-loaded microspheres and blank microspheres in presence of free risperidone in 0.02 M PBS containing 0.02% Tween®80 at 37°C. Molecular weight was monitored by gel permeation chromatography. Risperidone and blank microspheres had similar size distribution and were spherical with a relatively nonporous smooth surface. The presence of risperidone within the microspheres enhanced the hydrolytic degradation in both polymeric matrices with faster degradation occurring in 65:35 PLGA. The molecular weight decreased according to pseudo-first-order kinetics for all the formulations. During the degradation study, the surface morphology of drug-loaded microspheres was affected by the presence of risperidone and resulted in shriveled microspheres in which there appeared to be an intrabatch variation with the larger microspheres being less shriveled than the smaller ones. When blank microspheres were incubated in free risperidone solutions, a concentration-dependent effect on the development of surface porosity could be observed. Risperidone accelerates the hydrolytic degradation of PLGA, presumably within the microenvironment of the drug-loaded particles, and this phenomenon must be taken into consideration in designing PLGA dosage forms of tertiary amine drugs
The importance of stereochemistry on the actions of vitamin D.
No full textThe seco-steroid hormone 1α,25-dihydroxyvitamin D(3) [1α,25(OH)(2)D(3)] is the most potent natural metabolite of vitamin D(3) and regulates primarily calcium and phosphate homeostasis, but also as a regulator of specific differentiation and of the immune system. Most, if not all, of the biological actions of 1α,25(OH)(2)D(3) are mediated through its specific receptor, the vitamin D receptor (VDR), which is a member of the nuclear receptor superfamily acting as a ligand-dependent transcription factor with coactivators. 1α,25(OH)(2)D(3) has significant therapeutic potential in the treatment of osteoporosis, rickets, secondary hyperparathyroidism, psoriasis, and renal osteodystrophy. However, the use of 1α,25(OH)(2)D(3) itself is limited because it induces significant hypercalcemia. Vitamin D is a highly flexible molecule and a very large number of analogs have been synthesized by industry and academia in an attempt to provide beneficial therapeutic agents with low calcemic activity. Chemical modifications of every portion of the vitamin D(3) molecule (the A, C, and D rings, the 17β-aliphatic side chain, and the 5,6,7,8-diene moiety) have been reported, with the most of the interesting analogs resulting from a combination of several modifications. The three-dimensional structure of both rat and human VDR-LBD have provided significant information for our understanding of the structure-function relationship (SFR) of vitamin D and some synthetic analogs. In this review, we focus on the current understanding of the relationship between selected stereochemical modifications of key structural components (i.e. A-ring, CD-ring and Side-chain) of the 1α,25(OH)(2)D(3) molecule and their effect on biological potency and selectivity. Based on current information, suggestions for the structure-based design of therapeutically valuable vitamin D analogs will conclude the review
Cytoskeletal alterations associated with donor age and culture interval for equine oocytes and potential zygotes that failed to cleave after intracytoplasmic sperm injection
No full textIntracytoplasmic sperm injection (ICSI) is an established method to fertilise equine oocytes, but not all oocytes cleave after ICSI. The aims of the present study were to examine cytoskeleton patterns in oocytes after aging in vitro for 0, 24 or 48h (Experiment 1) and in potential zygotes that failed to cleave after ICSI of oocytes from donors of different ages (Experiment 2). Cytoplasmic multiasters were observed after oocyte aging for 48h (P<0.01). A similar increase in multiasters was observed with an increased interval after ICSI for young mares (9-13 years) but not old (20-25 years) mares. Actin vesicles were observed more frequently in sperm-injected oocytes from old than young mares. In the present study, multiasters appeared to be associated with cell aging, whereas actin vesicles were associated with aging of the oocyte donor
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