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111.
Chondrogenic potential of adipose tissue-derived stromal cells in vitro and in vivo. 总被引:46,自引:0,他引:46
Geoffrey R Erickson Jeffrey M Gimble Dawn M Franklin Henry E Rice Hani Awad Farshid Guilak 《Biochemical and biophysical research communications》2002,290(2):763-769
Articular cartilage exhibits little intrinsic repair capacity, and new tissue engineering approaches are being developed to promote cartilage regeneration using cellular therapies. The goal of this study was to examine the chondrogenic potential of adipose tissue-derived stromal cells. Stromal cells were isolated from human subcutaneous adipose tissue obtained by liposuction and were expanded and grown in vitro with or without chondrogenic media in alginate culture. Adipose-derived stromal cells abundantly synthesized cartilage matrix molecules including collagen type II, VI, and chondroitin 4-sulfate. Alginate cell constructs grown in chondrogenic media for 2 weeks in vitro were then implanted subcutaneously in nude mice for 4 and 12 weeks. Immunohistochemical analysis of these samples showed significant production of cartilage matrix molecules. These findings document the ability of adipose tissue-derived stromal cells to produce characteristic cartilage matrix molecules in both in vitro and in vivo models, and suggest the potential of these cells in cartilage tissue engineering. 相似文献
112.
Cohen DN Erickson SE Xiang Y Rossmann MG Anderson DL 《Journal of molecular biology》2008,378(4):804-817
Low copy number proteins within macromolecular complexes, such as viruses, can be critical to biological function while comprising a minimal mass fraction of the complex. The Bacillus subtilis double-stranded DNA bacteriophage phi 29 gene 13 product (gp13), previously undetected in the virion, was identified and localized to the distal tip of the tail knob. Western blots and immuno-electron microscopy detected a few copies of gp13 in phi 29, DNA-free particles, purified tails, and defective particles produced in suppressor-sensitive (sus) mutant sus13(330) infections. Particles assembled in the absence of intact gp13 (sus13(342) and sus13(330)) had the gross morphology of phi 29 but were not infectious. gp13 has predicted structural homology and sequence similarity to the M23 metalloprotease LytM. Poised at the tip of the phi 29 tail knob, gp13 may serve as a plug to help restrain the highly pressurized packaged genome. Also, in this position, gp13 may be the first virion protein to contact the cell wall in infection, acting as a pilot protein to depolymerize the cell wall. gp13 may facilitate juxtaposition of the tail knob onto the cytoplasmic membrane and the triggering of genome injection. 相似文献
113.
Identification and characterization of an outer membrane protein, OmpX, in Escherichia coli that is homologous to a family of outer membrane proteins including Ail of Yersinia enterocolitica. 总被引:1,自引:3,他引:1
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We previously reported that a region of the Escherichia coli chromosome at 18 min increased E sigma E activity when cloned in multicopy (J. Mecsas, P. E. Rouviere, J. W. Erickson, T. J. Donohue, and C. A. Gross, Genes Dev. 7:2618-2628, 1993). In the present report, we identify and characterize the gene responsible for the increase in E sigma E activity. This gene is in a monocistronic operon with two promoters and a rho-independent terminator. Sequence analysis of this gene indicated that it encodes an outer membrane protein which is 83% identical to OmpX in Enterobacter cloacae, leading us to name this gene ompX. There are four other proteins that are homologous to OmpX. Several of these proteins, Ail of Yersinia enterocolitica and Rck and PagC of Salmonella typhimurium, have properties that allow bacteria to adhere to mammalian cells, survive exposure to human serum, and/or survive within macrophages. We therefore characterized strains deleted for ompX for their growth phenotypes, E sigma E activity, serum resistance, and adherence to mammalian cells. No differences in growth rates, serum resistance, or adherence to mammalian cells were observed; however, E sigma E activity was dependent on expression of OmpX in certain strain backgrounds. 相似文献
114.
Denis A. Magoffin Gregory F. Erickson 《In vitro cellular & developmental biology. Plant》1988,24(9):862-870
Summary Although luteinizing hormone (LH) alone stimulates ovarian interstitial cells cultured in serum-free medium to synthesize
large amounts of androgens, there seem to be additional factors in vivo that modulate the time course and magnitude of the
cellular responses to LH. In an attempt to develop a more nearly physiologic cell culture model, lipoproteins, insulin, and
insulinlike growth factor-I (IGF-I) were added to the serum-free medium. The effects of these modifications on androgen biosynthesis
by dispersed cells from ovaries of hypophysectomized immature rats cultured in 96-well tissue culture plates were examined.
A saturating dose of LH stimulated a 25-fold increase in androsterone synthesis at 2 d, which decreased at 4 and 6 d. Addition
of human high density (hHDL) or human low density lipoprotein (hLDL) caused a 2.5-fold increase in LH-stimulated androsterone
synthesis. Cells were approximately twice as sensitive to hHDL (ED50=5.5±0.5 μg cholesterol/ml) compared to hLDL (ED50=9.1±1.1 μg cholesterol/ml). Surprisingly, rat HDL caused only a 40% increase in LH-stimulated androsterone synthesis. When
insulin alone was added to cells cultured with a saturating dose of LH, there was a 2.8-fold increase in androsterone synthesis.
Addition of hHDL and insulin together caused a synergistic increase in LH-stimulated androsterone synthesis. In contrast to
hHDL, which did not change the time course of LH-stimulated androsterone production, insulin prolonged maximal LH-stimulated
androsterone synthesis at 4 and 6 d. Inasmuch as the ED50 for insulin action (1.3±0.1 μg/ml) was supraphysiologic, the effects of IGF-I on LH-stimulated androgen synthesis were examined.
IGF-I mimicked all of the effects of insulin, but at a physiologic concentration (ED50=2.5±0.3 ng/ml). Ovarian cells cultured in serum-free medium supplemented with hHDL and insulin or IGF-I exhibit responses
that closely approximate the physiologic responses observed in vivo. These results suggest that lipoproteins and IGF-I are
important physiologic stimulators of ovarian theca-interstitial cell androgen biosynthesis which, when added to the serum-free
medium, make the cellular responses in this in vitro model more nearly approximate the responses in vivo.
This research was supported by research center grant HD 12303 from the National Institute of Child Health and Human Development,
Bethesda, MD, and USCD Academic Senate grant RM-169M 相似文献
115.
The helicase domain of the TMV replicase proteins induces the N-mediated defence response in tobacco 总被引:10,自引:0,他引:10
F. Les Erickson Steve Holzberg Alejandro Calderon-Urrea Vanessa Handley Michael Axtell Catherine Corr Barbara Baker 《The Plant journal : for cell and molecular biology》1999,18(1):67-75
Tobacco mosaic virus (TMV) induces the hypersensitive response (HR) in tobacco plants containing the N gene. This defence response is characterized by cell death at the site of virus infection and inhibition of viral replication and movement. A previous study indicated that a portion of the TMV replicase containing a putative helicase domain is involved in HR induction. Here, this observation is confirmed and extended by showing that non-viral expression of a 50 kDa TMV helicase fragment (p50) is sufficient to induce the N-mediated HR in tobacco. Like the HR elicited by TMV infection, transgenic expression of p50 induces a temperature-sensitive defence response. We demonstrate that recombinant p50 protein has ATPase activity, as suggested by the presence of conserved sequence motifs found in ATPase/helicase enzymes. A point mutation that alters one of these motifs abolishes ATPase activity in vitro but does not affect HR induction. These results suggest that features of the TMV helicase domain, independent of its enzymatic activity, are recognized by N-containing tobacco to induce TMV resistance. 相似文献
116.
The penicillin acylase activity of Penicillium chrysogenum was studied. Washed mycelial suspensions of a high penicillin-producing and a nonproducing strain were found to be similar in respect to relative acylase activity on benzylpenicillin, 2-pentenylpenicillin, heptylpenicillin, and phenoxymethylpenicillin. The relative rates for both strains, as determined by 6-aminopenicillanic acid formation, were approximately 1.0, 2.5, 3.5, and 6.0 on the penicillins in the order given. The high producing strain formed both 6-aminopenicillanic acid and "natural" penicillins in fermentations to which no side-chain precursor had been added. Therefore, its demonstrated ability to cleave the natural penicillins, 2-pentenylpenicillin and heptylpenicillin, suggests that at least some of the 6-aminopenicillanic acid produced during such fermentations arises from the hydrolysis of the natural penicillins. At pH 8.5, the mycelial acylase activity of the nonproducing strain was about three times that at pH 6.0; at 35 C, it was about 1.5 times as active as it was at 30 C. When tested on penicillin G or V, no differences in either total or specific penicillin acylase activity were observed among mycelia harvested from cultures of the nonproducer to which penicillin G, penicillin V, or no penicillin had been added. Acetone-dried mycelium from both strains displayed acylase activity, but considerably less than that shown by viable mycelium. Culture filtrates were essentially inactive, although a very low order of activity was detected when culture filtrate from the nonproducer was treated with acetone and the acetone-precipitated material was assayed in a minimal amount of buffer. 相似文献
117.
Ralph O. Erickson 《American journal of botany》1960,47(5):350-351
Erickson , Ralph O. (U. Pennsylvania, Philadelphia.) Nomogram for the plastochron index. Amer. Jour. Bot. 47(5) : 350—351. Illus. 1960.–In an earlier paper, a plastochron index was described which specifies the development age of a shoot with some precision. The plastochron index of a shoot can be estimated quickly by use of the nomogram described here. 相似文献
118.
Maurice Ogur Ralph O. Erickson Gloria U. Rosen Katharine B. Sax Constance Holden 《Experimental cell research》1951,2(1):73-89
Methods are described for preparing cell suspensions of Lilium microsporocytes, microspores and pollen grains; for obtaining cell counts of these suspensions; and for their analysis for pentose nucleic acid (PNA) and desoxypentose nucleic acid (DNA).The results of these analyses have been calculated to nucleic acid content in μμg per microsporocyte, microspore or pollen grain, and the results related to logarithm of flower bud length, an index of the developmental status of the cells, and of their temporal relationship to meiosis, microspore mitosis and opening of the flower.DNA content per cell drops sharply at the end of meiosis, with the formation of four microspores from each microsporocyte. It then increases gradually during the microspore interphase between meiosis and the microspore mitosis. At microspore mitosis DNA content doubles rapidly. In the development of the resulting binucleate pollen grain, from microspore mitosis until the opening of the flower, there is a further gradual increase of DNA content. PNA content of these cells follows the same pattern up to microspore mitosis at a level about twice that of DNA, increases sharply at mitosis, and continues to increase rapidly at a rate nine times that for DNA in the maturing pollen grain.The absolute amounts of DNA and PNA are great. At the time of anthesis the two-celled pollen grain contains about 375 μμg of DNA and 1705 μμg of PNA. 相似文献
119.
120.
Although most known human teratogens often produce a combination of birth defects in an affected infant, surveillance programs aimed at detecting epidemics of birth defects usually only monitor rates of individual defects. A drawback to this approach is that an increase in the rate of infants affected with a specific combination of defects may lead to little or no increase in the rates of component defects. Using the Poisson distribution, we show that, compared with monitoring for individual defects, monitoring for combinations of two and three defects may require fewer numbers of births to detect an epidemic. In general, an increase can be detected more rapidly by monitoring the rates of defect combinations than by monitoring the rates of individual defects if most affected infants have combinations of defects rather than isolated defects. For example, in the case of Congenital rubella syndrome (CRS), monitoring for the combination of cataracts with deafness and/or patent ductus arteriosus could have led to earlier detection of an epidemic than could monitoring for cataracts alone. In contrast, in the case of thalidomide embryopathy, monitoring for reduction defects of upper limbs in combination with reduction defects of lower limbs and/or microtia/anotia would not have led to earlier detection of an epidemic than would monitoring for reduction defects of upper limbs alone. This is due mainly to the low frequency of defect combinations among affected cases. When used with regular monitoring for individual defects, surveillance of defect combinations can enhance the ability of monitoring programs to detect epidemics of birth defects. 相似文献