317 research outputs found

    Polysaccharides of St. John’s Wort Herb Stimulate NHDF Proliferation and NEHK Differentiation via Influence on Extracellular Structures and Signal Pathways

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    St. John's Wort herb extracts often contain undesirable or volitional polysaccharides. As polysaccharides exhibit structure-dependent biological functions in the present study water-soluble polysaccharides were extracted from herb material, fractionated by anion exchange chromatography into four main polysaccharide fractions (denominated as Hp1, Hp2, Hp3 and Hp4) and characterized by HPAEC-PAD, CE, IR and GC-MS. Biological activity on human skin keratinocytes and fibroblasts was assessed by investigation of their effect on proliferation, metabolism, cytotoxicity, apoptosis and differentiation. The underlying mechanisms were investigated in gene expression studies. Polysaccharide fraction Hp1 was mainly composed of β-D-glucose. Hp2, Hp3 and Hp4 contained pectic structures and arabinogalactan proteins varying in composition and quantity. Polysaccharides of Hp1 induced the keratinocyte differentiation by inhibiting the gene expression of the epidermal growth factor and insulin receptor. While the collagen secretion of fibroblasts was stimulated by each polysaccharide fraction only Hp1 stimulated the synthesis. The fibroblast proliferation was reduced by Hp1 and increased by Hp4. This effect was related to the influence on genes that referred to oxidative stress, metabolism, transcription processes and extracellular proteins. In conclusion polysaccharides have been shown as biologically active ingredients of aqueous St. John's Wort extracts with a relation between their structural characteristics and function

    Silvicultural aspects of woodland management in southeastern Minnesota

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    This archival publication may not reflect current scientific knowledge or recommendations

    Aerodynamic and Aeroacoustic Performance of Small UAV Propellers in Static Conditions

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    The proliferation of small multi-rotor UAVs in commercial, recreational, and surveillance spheres has garnered significant interest in the noise produced by these vehicles. The current research aims to study the relationship between the aerodynamic performance and acoustic characteristics of small-scale UAV propellers. Three commercially available propellers for the DJI Phantom 2/3 UAV were selected for preliminary development and validation of an aeroacoustic experimental test setup and associated data reduction methods. Propeller thrust, torque, and power measurements were recorded at static conditions. Upon successful validation of the test bench, acoustic measurements were taken at the propeller disk’s upstream and in-plane locations. The power spectral density of these acoustic signals was estimated using the modified periodogram (Welch’s) method to identify frequency content and calculate sound pressure levels (SPLs) at each of the observation locations. Additionally, time-frequency analysis verified the periodogram results and identified possible sources of transient noise at static thrust. These methods found the nonrotor noise to be a major contributor to the SPL at higher frequencies and the propeller noise dominating the SPL spectra at the lower frequencies. Experimental thrust, torque, power, and sound pressure level (SPL) data were then compared for each propeller to identify relationships between aerodynamic performance and acoustic characteristics with variations in propeller geometry and blade loading

    Branching ratios of radiative transitions in O VI

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    We study the branching ratios of the allowed and forbidden radiative transitions among the first few (9) fine structure levels of O VI using relativistic coupled cluster theory. We find irregular patterns for a number of transitions with in nn-complexes with n4n\le4. We have used the exisiting values of the allowed electric dipole (E1E1) transition as a benchmark of our theory. Good agreement with the existing values establish accuracies of not only the theoretical method but the basis function as well. In general the electric quadrupole (E2E2) transition probabilities are greater in magnitude than magnetic dipole (M1M1) transition probabilities, whereas for medium atomic transition frequencies they are of the same order of magnitude. On the other hand if the transitions involved are between two fine structure components of the same term, then the M1M1 transition probability is more probable than that of E2E2. We have analyzed these trends with physical arguments and order of magnitude estimations. The results presented here in tabular and graphical forms are compared with the available theoretical and observed data. Graphical analysis helps to understand the trends of electric and magnetic transitions for the decay channels presented here. Our calculated values of the lifetimes of the excited states are in very good agreement with the available results.Comment: Submitted to J. Phys. B, March 200

    Continued Benefits of Methylphenidate in ADHD After 2 Years in Clinical Practice:A Randomized Placebo-Controlled Discontinuation Study

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    Objective: The benefits of long-term use of methylphenidate treatment in children and adolescents with attention deficit hyperactivity disorder (ADHD), as frequently prescribed in clinical practice, are unclear. The authors investigated whether methylphenidate remains beneficial after 2 years of use. Methods: Ninety-four children and adolescents (ages 8-18 years) who had been treated in regular care with methylphenidate for more than 2 years were randomly assigned to double-blind continuation of treatment for 7 weeks (36 or 54 mg/day of extended-release methylphenidate) or gradual withdrawal over 3 weeks, to 4 weeks of placebo. The primary outcome measure was the investigator-rated ADHD Rating Scale (ADHD-RS); secondary outcome measures were the investigator-rated Clinical Global Impressions improvement scale (CGI-I) and the Conners' Teacher Rating Scale-Revised: Short Form (CTRS-R:S). Continuous ratings were analyzed with mixed model for repeated measures analyses, and the CGI-I with a chi-square test. Results: The mean ADHD-RS scores at baseline for the continuation and discontinuation groups, respectively, were 21.4 (SD=9.7) and 19.6 (SD=8.9); after 7 weeks, the mean scores were 21.9 (SD=10.8) and 24.7 (SD=11.4), with a significant between-group difference in change over time of 24.6 (95% CI=28.7, 20.56) in favor of the group that continued methylphenidate treatment. The ADHD-RS inattention subscale and the CTRS-R: S ADHD index and hyperactivity subscale also deteriorated significantly more in the discontinuation group. The CGI-I indicated worsening in 40.4% of the discontinuation group, compared with 15.9% of the continuation group. Conclusions: Continued treatment with methylphenidate remains effective after long-term use. Some individual patients may, however, be withdrawn from methylphenidate without deterioration. This finding supports guideline recommendations that patients be assessed periodically to determine whether there is a continued need for methylphenidate treatment

    Effects of Discontinuing Methylphenidate on Strengths and Difficulties, Quality of Life and Parenting Stress

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    Objectives: To study the effects of discontinuation of long-term methylphenidate use on secondary outcome measures of strengths and difficulties, quality of life (QoL), and parenting stress. Methods: Ninety-four children and adolescents aged 8 to 18 years who had used methylphenidate for over 2 years were randomly assigned to double-blind continuation of treatment for 7 weeks (36 or 54 mg extended release methylphenidate) or to gradual withdrawal over 3 to 4 weeks placebo. We used mixed models for repeated measures to investigate effects on parent, teacher, and child ratings of hyperactivity/inattention and comorbid symptoms with the Strengths and Difficulties Questionnaire (SDQ), investigator- and teacher-rated oppositional symptoms (Conners Teacher Rating Scale-Revised: short form [CTRS-R:S]), and parent-rated aggression with the Retrospective Modified Overt Aggression Scale. QoL was assessed with the Revised Questionnaire for Children and Adolescents to record health-related quality of life and parenting stress with the Nijmegen Parental Stress Index. Results: Hyperactivity/inattention scores from the parent- and teacher-rated SDQ (difference in mean change over time of respectively: -1.1 [95% confidence interval, CI, -2.0 to -0.3]; p = 0.01; -2.9 [95% CI -2.9 to -0.7; p = 0.01]) and oppositional scores of the teacher-rated CTRS-R:S (difference in mean change -1.9 95% CI [-3.1 to -0.6; p <0.01]) deteriorated to a significantly larger extent in the discontinuation group than in the continuation group. We did not find effects on other symptom domains, aggression, QoL, and parenting stress after discontinuation of methylphenidate. Conclusion: Our study suggests beneficial effects of long-term methylphenidate use beyond 2 years for oppositional behaviors in the school environment. Similarly, beneficial effects were found on hyperactivity-inattention symptoms as rated by parent and teacher scales, confirming our primary study on investigator ratings of attention-deficit/hyperactivity disorder. However, discontinuation of methylphenidate did not appear to have impact on other comorbid problems or aspects of the child's or parental functioning
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