3,401 research outputs found
The disposition and pharmacokinetics of Dioscorea nipponica Makino extract in rats
This study was aimed to investigate the disposition and pharmacokinetics of the total saponins of dioscorea (TSD) in rats. Male Sprague-Dawley rats were orally administrated with 3H labeled TSD at a single dose ratio of 80 mg TSD per 1 kg rat. Blood samples and feces were collected at different time points to measure the level of TSD activity. At the final time point, determination of the disposition of TSD in lung, kidney, heart, liver, adrenal, and small intestine were performed. From the blood samples' emission of radioactivity, pharmacokinetic parameters were derived as T1/2 = 33.33 ± 4.48 h, T max = 6.5 ± 0.71 h, AUC = 119400 ± 421097.67, and C max = 2643.33 ± 192.26 dpm/ml. There was 51.609% of 3H labeled substance excreted in 24 h. These results suggested that blood concentration of 3H-TSD was extremely low and the majority of TSD was excreted in the feces. The TSD was extensively distributed to multitissues. The radioactivity level was measured to be the highest in the liver, adrenal gland, and wall of the gastrointestinal tract. The radioactivity of TSD was still being detected in blood after 96 h. This showed TSD was excreted in vivo very slowly. © 2008 Academic Journals.published_or_final_versio
Caffeine Suppresses GABA Receptor-Mediated Current in Rat Primary Sensory Neurons Via Inhibition of Intracellular Phosphodiesterase
In acutely isolated rat primary sensory neurons, the effects of caffeine on GABA receptormediated current (IGABA) were investigated using a whole-cell patch clamp technique. We found
that applications of GABA (10-1000 µM) induced inward currents in a concentration-dependent
manner; the currents manifested obvious desensitization. Pretreatment with caffeine (0.01-
100 µM) suppressed IGABA in a noncompetitive manner; caffeine shifted the concentration –
response curve for GABA downwards compared to the control. Theophylline showed a similar
and stronger inhibitory effect on IGABA. Isolated application of 1 µM diazepam enhanced
IGABA, while pretreatment with 10 µM caffeine and 1 µM diazepam suppressed this current.
Intracellular application of the protein kinase A inhibitor H-8 dramatically weakened the
inhibitory effect of caffeine on IGABA. Because primary afferent depolarization is related to
GABAA receptors, our results suggest that caffeine might antagonize presynaptic inhibitory
effects of primary afferents, probably via inhibition of intracellular phosphodiesterase.Досліджували впливи кофеїну на струми, опосередковані рецепторами ГАМК (IGABA), в гостроізольованих первинних нейронах щура; використовували методику петчклемп у конфігурації «ціла клітина». Аплікації ГАМК
(10–1000 мкМ) викликали струми вхідного напрямку, амплітуда котрих була залежною від концентрації; струми демонстрували яскраво виражену десенситизацію. Попередня обробка кофеїном (0.01–100 мкМ) призводила до
неконкурентного пригнічення IGABA. Вплив кофеїну зміщував вниз криву концентрація–відповідь для ГАМК порівняно з контролем. Теофілін демонстрував подібні й навіть
сильніші гальмівні впливи на IGABA. Ізольована аплікація 1
мкМ діазепаму посилювала IGABA, тоді як попередня обробка
10 мкМ кофеїну перед дією 1 мкМ діазепаму пригнічувала цей струм. Внутрішньоклітинна аплікація H-8 (інгібітору протеїнкінази А) дуже значно послаблювала гальмівний
вплив кофеїну на IGABA. Оскільки деполяризація терміналий первинних аферентів опосередковується рецепторами ГАМК, наші результати вказують на те, що кофеїн може
протистояти пресинаптичному гальмуванню первинних аферентів. Ефекти кофеїну опосередковуються гальмуванням
внутрішньоклітинної фосфодіестерази
Butterfly Detection and Classification Based on Integrated YOLO Algorithm
Insects are abundant species on the earth, and the task of identification and
identification of insects is complex and arduous. How to apply artificial
intelligence technology and digital image processing methods to automatic
identification of insect species is a hot issue in current research. In this
paper, the problem of automatic detection and classification recognition of
butterfly photographs is studied, and a method of bio-labeling suitable for
butterfly classification is proposed. On the basis of YOLO algorithm, by
synthesizing the results of YOLO models with different training mechanisms, a
butterfly automatic detection and classification recognition algorithm based on
YOLO algorithm is proposed. It greatly improves the generalization ability of
YOLO algorithm and makes it have better ability to solve small sample problems.
The experimental results show that the proposed annotation method and
integrated YOLO algorithm have high accuracy and recognition rate in butterfly
automatic detection and recognition.Comment: 13th ICGEC 2019: Qingdao, Chin
Shape controlled synthesis of PbS nanocrystals by a solvothermal-microemulsion approach
Shape controlled synthesis of PbS nanoparticles, cubes, and nanowires has been realized by a so-called solvothermal-microemulsion technique in a sodium dodecyl sulfate (SDS)/hexane/hexanol/water microemulsion system using different sulfur source. The effect of different sulfur source and temperature on the shape of PbS nanocrystallites was investigated. The results demonstrated that the combination of solvothermal process and microemulsion technique could provide a useful tool for the synthesis of other nanocrysals with unusual shape and structures. (C) 2004 Published by Elsevier B.V
Emergence of scale-free leadership structure in social recommender systems
The study of the organization of social networks is important for
understanding of opinion formation, rumor spreading, and the emergence of
trends and fashion. This paper reports empirical analysis of networks extracted
from four leading sites with social functionality (Delicious, Flickr, Twitter
and YouTube) and shows that they all display a scale-free leadership structure.
To reproduce this feature, we propose an adaptive network model driven by
social recommending. Artificial agent-based simulations of this model highlight
a "good get richer" mechanism where users with broad interests and good
judgments are likely to become popular leaders for the others. Simulations also
indicate that the studied social recommendation mechanism can gradually improve
the user experience by adapting to tastes of its users. Finally we outline
implications for real online resource-sharing systems
The lncRNA HOTAIR transcription is controlled by HNF4α-induced chromatin topology modulation
The expression of the long noncoding RNA HOTAIR (HOX Transcript Antisense Intergenic RNA) is largely deregulated in epithelial cancers and positively correlates with poor prognosis and progression of hepatocellular carcinoma and gastrointestinal cancers. Furthermore, functional studies revealed a pivotal role for HOTAIR in the epithelial-to-mesenchymal transition, as this RNA is causal for the repressive activity of the master factor SNAIL on epithelial genes. Despite the proven oncogenic role of HOTAIR, its transcriptional regulation is still poorly understood. Here hepatocyte nuclear factor 4-α (HNF4α), as inducer of epithelial differentiation, was demonstrated to directly repress HOTAIR transcription in the mesenchymal-to epithelial transition. Mechanistically, HNF4α was found to cause the release of a chromatin loop on HOTAIR regulatory elements thus exerting an enhancer-blocking activity
Inhibition of the tyrosine phosphatase SHP-2 suppresses angiogenesis in vitro and in vivo
Endothelial cell survival is indispensable to maintain endothelial integrity and initiate new vessel formation. We investigated the role of SHP-2 in endothelial cell survival and angiogenesis in vitro as well as in vivo. SHP-2 function in cultured human umbilical vein and human dermal microvascular endothelial cells was inhibited by either silencing the protein expression with antisense-oligodesoxynucleotides or treatment with a pharmacological inhibitor (PtpI IV). SHP-2 inhibition impaired capillary-like structure formation (p < 0.01; n = 8) in vitro as well as new vessel growth ex vivo (p < 0.05; n = 10) and in vivo in the chicken chorioallantoic membrane (p < 0.01, n = 4). Additionally, SHP-2 knock-down abrogated fibroblast growth factor 2 (FGF-2)-dependent endothelial proliferation measured by MTT reduction ( p ! 0.01; n = 12). The inhibitory effect of SHP-2 knock-down on vessel growth was mediated by increased endothelial apoptosis ( annexin V staining, p ! 0.05, n = 9), which was associated with reduced FGF-2-induced phosphorylation of phosphatidylinositol 3-kinase (PI3-K), Akt and extracellular regulated kinase 1/2 (ERK1/2) and involved diminished ERK1/2 phosphorylation after PI3-K inhibition (n=3). These results suggest that SHP-2 regulates endothelial cell survival through PI3-K-Akt and mitogen-activated protein kinase pathways thereby strongly affecting new vessel formation. Thus, SHP-2 exhibits a pivotal role in angiogenesis and may represent an interesting target for therapeutic approaches controlling vessel growth. Copyright (C) 2007 S. Karger AG, Basel
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