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991.
Yin C Ying L Zhang PC Zhuo RX Kang ET Leong KW Mao HQ 《Journal of biomedical materials research. Part A》2003,67(4):1093-1104
Galactosylated surface is an attractive substrate for hepatocyte culture because of the specific interaction between the galactose ligand and the asialoglycoprotein receptor on hepatocytes. In this study, we described a scheme to achieve high density of immobilized galactose ligands on polyethylene terephthalate (PET) surface by first surface-grafting polyacrylic acid on plasma-pretreated PET film under UV irradiation, followed by conjugation of a galactose derivative (1-O-(6'-aminohexyl)-D-galactopyranoside) to the grafted polyacrylic acid chains. A high galactose density of 513 nmol/cm(2) on the PET surface was used in this study to investigate the behavior of cultured hepatocyte. This engineered substrate showed high affinity to fluorescein isothiocyanate-lectin binding. Primary rat hepatocytes, when seeded at a density of 2 x 10(5) cells/cm(2), attached to the galactosylated PET substrate at a similar efficiency compared with collagen-coated substrate. The hepatocytes spontaneously formed aggregates 1 day after cell seeding and showed better maintenance of albumin secretion and urea synthesis functions than those cultured on collagen-coated surface. 相似文献
992.
Preparation of poly(L-lactic acid) and poly(DL-lactic-co-glycolic acid) foams by use of ice microparticulates 总被引:22,自引:0,他引:22
Biodegradable foams of poly(L-lactic acid) (PLLA) and poly(DL-lactic-co-glycolic acid) (PLGA) for tissue engineering were fabricated by a porogen-leaching technique using ice microparticulates as the porogen material. PLLA or PLGA solution in chloroform was mixed with ice microparticulates. The mixtures were frozen by being placed in molds in liquid nitrogen and freeze-dried to form the foams. Scanning electron microscopic observation of the PLLA and PLGA foams showed that evenly distributed and interconnected pore structures were formed in these foams. The porosity and surface area of the foams increased with an increase in the weight fraction of the ice microparticulates, while the median pore size remained unchanged. The pore structures of the foams could be manipulated by controlling processing variables such as the size and weight fraction of the ice microparticulates and polymer concentration. 相似文献
993.
Systemic Chlamydia trachomatis infection in mice: a comparison of lymphogranuloma venereum and trachoma biovars. 总被引:1,自引:7,他引:1 下载免费PDF全文
We developed a murine model of systemic infection with Chlamydia trachomatis biovar lymphogranuloma venereum (LGV). The pathological features of this infection resemble those of human LGV infection since both are characterized by granuloma formation. Mice developed resistance to reinfection with LGV, and this resistance was based on cellular immune mechanisms since it was transferable with immune spleen cells but not with immune serum. Resistance required viable organisms for induction. We compared LGV biovar infection with trachoma biovar infection. Trachoma biovar produced similar but less marked microbiological and pathological features. Cross-immunity was less apparent between serovars from trachoma and LGV biovars than it was between serovars within the same biovar. This model of systemic C. trachomatis infection will be useful in exploring virulence features of LGV. 相似文献
994.
995.
研究单次及长期维持血液透析时尿毒症患者血液流变性改变的影响。结果表明,单次血透后,红细胞比积明显升高,红细胞刚性明显降低;血浆粘度、红细胞聚集指数、Casson粘度、血液屈服应力及低切至高切的全血粘度无明显改变。维持血透患者的红细胞比积、血浆粘度、红细胞聚集指数、Casson粘度、血液屈服应力均无明显改变。进一步研究发现,单次血透后血浆渗透比明显降低.这可能是引起红细胞比积升高、红细胞刚性降低的原因之一。 相似文献
996.
蒙古族、回族和汉族的发旋调查 总被引:2,自引:0,他引:2
对蒙古族、回族和汉族共6098例发旋进行了观察,结果:蒙古族单旋出现率高于回族和汉族,而双旋则低于这两个民族,差异极其显著(P<0.01)。三个民族男性双旋均高于本民族女性(P<0.01)。双旋的组合除文献报道的四种类型外,还有四种组合方式。 相似文献
997.
In anesthetized, spontaneously hypertensive rats (Okamoto-Aoki), injections of 0.75, 1.5, and 3.0 microgram/kg PGE2 into the jugular vein caused transient decreases (mean +/- SE) in arterial pressure of 21 +/- 2, 37 +/- 3, and 78 +/- 6 mmHg, respectively, before cervical vagotomy and of 1 +/- 1, 15 +/- 4, and 15 +/- 6 mmHg after cervical vagotomy. The vasodepressor effect of jugular vein injections of 3.0 microgram/kg PGE2, but not of lower doses, was depressed by vagotomy in normotensive Wistar-Kyoto and Sprague-Dawley rats. Vagotomy did not reduce the hypotensive response to intra-aortic injections of PGE2 in these hypertensive and normotensive rats. The depressor effect of PGE2 thus appears to have a significant reflex component mediated through cardiopulmonary receptors subserved by vagal afferents, with hypertensive rats exhibiting a lower threshold than normotensive rats. A vagally mediated reflex component to the depressor effect of PGE2 could not be demonstrated in normotensive rabbits or in rabbits and rats with chronic renovascular hypertension. Thus, a naturally occurring vasoactive substance can stimulate cardiopulmonary receptors subserved by vagal afferents in the rat, and spontaneously hypertensive rats appear to be especially sensitive to this effect. 相似文献
998.
H.J. Chen 《Neurobiology of aging》1981,2(3):215-219
Effects of aging on estrous cycles and LH release in response to luteinizing hormone releasing hormone (LHRH), castration, and estradiol benzoate were studied in the female golden hamster (Mesocricetus auratus). About 80% to 90% of female golden hamsters still cycled regularly when reaching 19–22 months of age. However, some animals showed age-induced irregularity of the estrous cycle which included an interruption of complete absence of estrous vaginal discharge. Young female hamsters (3–5 months) had significantly (p<0.01) higher basal LH concentration than old animals (19–22 months) in the morning of each stage of estrous cycle. LHRH elicited about 20–30 fold increase in serum LH concentrations in both young and old hamsters. No significant difference in LH release was observed between young and old hamsters in response to LHRH. In acyclic hamsters, the peak of LH release in response to LHRH was delayed. LHRH-induced LH release was greater in the morning of proestrus than during diestrus in both young and old hamsters. LH increase was significantly greater in the young than in old hamsters on the 13th and 15th day after castration. However, positive feedback stimulation of LH release by estradiol benzoate was the same in both young and old hamsters. These results indicate that in the female hamster, LH response to acute stimuli such as LHRH and estrogens is the same in the young as in the old animal and that circulating basal LH concentration may decrease or its degradation or clearance may increase during the aging process in female golden hamsters. Irregularity of estrous cycles in aging hamsters may be related to delayed responsiveness of pituitary LH to LHRH stimulation. 相似文献
999.
The bilayer structure of chitosan film and sponge was designed as a scaffold of skin tissue engineering and a dermis substitute. It was processed successively via the formation of a dense chitosan film by casting method and a porous chitosan sponge by lyophilization. The dry thickness of the film layer was 19.6 microm and that of the sponge layer was controlled at 60-80 microm. Porogens such as sodium chloride, glucose, and sucrose were used to create large pores of the chitosan sponge layer. Human neofetal dermal fibroblasts were seeded in the chitosan sponge layer and cultured for 4 weeks. It was found that the cells could grow and proliferate well in an extended shape on the flat bottom of large pores with 15-100 microm width and in spherical form on the rough pore walls or at the edges of micropores less than 5 microm. Fibroblasts after the culture could bind tightly with the sponge layer via newly formed extracellular matrices to give a living cell-matrix-chitosan composite. The bilayer chitosan material remained stable in shape and size during the cell culture. The results suggested that the bilayer chitosan material would be an alternative of collagen materials which was obviously contracted during cell culture. 相似文献
1000.