排序方式: 共有38条查询结果,搜索用时 31 毫秒
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New controlled drug-delivery systems are being explored to overcome the disadvantages of conventional dosage forms. For example, stimulated drug-delivery has been used to overcome the tolerance problems that occur with a constant delivery rate, to mimic the physiological pattern of hormonal concentration and to supply drugs on demand. Stimuli-sensitive polymers, which are potentially useful for pulsed drug delivery, experience changes in either their structure or their chemical properties in response to changes in environmental conditions. Environmental stimuli include temperature, pH, light (ultraviolet or visible), electric field or certain chemicals. Volume changes of stimuli-sensitive gel networks are particularly responsive to external stimuli, but swelling is slow to occur. As well as being useful in the controlled release of drugs, such systems also provide insight into intermolecular interactions. Here we report on a novel polymeric system, which rapidly changes from a solid state to solution in response to small electric currents, by disintegration of the solid polymer complex into two water-soluble polymers. We show that the modulated release of insulin, and by extension other macromolecules, can be achieved with this polymeric system. 相似文献
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Rapid expansion of big-box store in developing country caused typical archetypal change in market structure: Success to the Successful, because big-box stores armed with modernized infrastructure and management capability are absorbing the once customers of the traditional market like a black hole. Facing rapid change in market structure and surmounting pleas from traditional market merchants, government took an inevitable intervention with law regulating the big-box store's business and improving traditional market's competence building. Not so long, however, did government confront policy resistance from both sides: Still ongoing polarization of both side's sales. This study articulates behavior over time of market structure with causal loop diagrams of which causalities are extracted from literatures. This study provides significant contribution to policy makers and traditional markets' merchants in other developing countries like India and China, as well as Korea. 相似文献
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A PHD finger of NURF couples histone H3 lysine 4 trimethylation with chromatin remodelling 总被引:1,自引:0,他引:1
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The mouse Ames waltzer hearing-loss mutant is caused by mutation of Pcdh15, a novel protocadherin gene 总被引:16,自引:0,他引:16
The neuroepithelia of the inner ear contain hair cells that function as mechanoreceptors to transduce sound and motion signals. Mutations affecting these neuroepithelia cause deafness and vestibular dysfuction in humans. Ames waltzer (av) is a recessive mutation found in mice that causes deafness and a balance disorder associated with the degeneration of inner ear neuroepithelia. Here we report that the gene that harbours the av mutation encodes a novel protocadherin. Cochlear hair cells in the av mutants show abnormal stereocilia by 10 days after birth (P10). This is the first evidence for the requirement of a protocadherin for normal function of the mammalian inner ear. 相似文献
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黄虔 《暨南大学学报(自然科学与医学版)》1998,(6)
氧张力是炎症反应、再灌注损伤和动脉粥样硬化形成的致病因素。这些病变的共同点是内皮细胞表面的白细胞粘附增加。我们用几种抗氧化剂:DCI,Chrysin,PDTC和Probucol在流动条件下(切变力在06~24dyn/cm2)实验其对内皮细胞表面白细胞粘附的影响,用化学发光法分析这几种抗氧化剂的抗氧化活性。结果显示:PDTC和Probucol对外周血有核细胞氧自由基的产生没有抑制作用,Chrysin可轻度抑制,DCI可明显抑制活性氧的产生。相反,PDTC(最大半抑制量8×10-4mol和Chrysin最大半抑制量5×10-5mol)可抑制细胞对经TNFα刺激的人脐带静脉内皮细胞(HUVEC)的粘附。DCI和Probucol对各种切变力范围的细胞粘附无作用。抗氧化剂对内皮细胞表面的白细胞粘附的抑制作用不能单用其抗氧性特性来解释。可能的作用机理是这类物质直接作用转录因子NF-kB的结果 相似文献
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C H Kwon X Zhu J Zhang L L Knoop R Tharp R J Smeyne C G Eberhart P C Burger S J Baker 《Nature genetics》2001,29(4):404-411
Somatic inactivation of PTEN occurs in different human tumors including glioblastoma, endometrial carcinoma and prostate carcinoma. Germline mutations in PTEN result in a range of phenotypic abnormalities that occur with variable penetrance, including neurological features such as macrocephaly, seizures, ataxia and Lhermitte-Duclos disease (also described as dysplastic gangliocytoma of the cerebellum). Homozygous deletion of Pten causes embryonic lethality in mice. To investigate function in the brain, we used Cre-loxP technology to selectively inactivate Pten in specific mouse neuronal populations. Loss of Pten resulted in progressive macrocephaly and seizures. Neurons lacking Pten expressed high levels of phosphorylated Akt and showed a progressive increase in soma size without evidence of abnormal proliferation. Cerebellar abnormalities closely resembled the histopathology of human Lhermitte-Duclos disease. These results indicate that Pten regulates neuronal size in vivo in a cell-autonomous manner and provide new insights into the etiology of Lhermitte-Duclos disease. 相似文献
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Kim DS Jeong YM Moon SI Kim SY Kwon SB Park ES Youn SW Park KC 《Cellular and molecular life sciences : CMLS》2006,63(22):2661-2668
Indole-3-carbinol (I3C) has been found to act against several types of cancer, while ultraviolet B (UVB) is known to induce
the apoptosis of human melanoma cells. Here, we investigated whether I3C can sensitize G361 human melanoma cells to UVB-induced
apoptosis. We examined the effects of combined I3C and UVB (I3C/UVB) at various dosages. I3C (200 μM)/UVB (50 mJ/cm2) synergistically reduced melanoma cell viability, whereas I3C (200 μM) or UVB (50 mJ/cm2), separately, had little effect on cell viability. DNA fragmentation assays indicated that I3C/UVB induced apoptosis. Further
results show that I3C/UVB activates caspase-8, −3, and Bid and causes the cleavage of poly(ADP-ribose) polymerase. Moreover,
I3C decreased the expression of the anti-apoptotic protein, Bcl-2, whereas UVB increased the translocation of Bax to mitochondria.
Thus, an increased Bax/Bcl-2 ratio by I3C/UVB may result in melanoma apoptosis. In conclusion, our study demonstrated that
I3C sensitizes human melanoma cells by down-regulating Bcl-2.
Received 5 July 2006; received after revision 25 August 2006; accepted 11 September 2006 相似文献
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