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31.
Koichi Hirata Tadashi Oku Aaron E. Freeman 《In vitro cellular & developmental biology. Plant》1982,18(9):789-799
Summary Twenty to twenty-two days postcoitum mouse fetal pancreas organ bits were cultured on the dermal surface of irradiated pigskin
as a substrate. The medium used for long term culture consisted of Eagle’s Minimum Essential Medium with the addition of 10%
bovine serum, 0.02 U/ml insulin, 0.025 μg/ml glucagon, 3.63 μg/ml hydrocortisone, 100 μg/ml soybean trypsin inhibitor or 10−8
M atropine. When the medium lacked trypsin inhibitor or atropine but contained the three hormones, the pigskin support began
to be destroyed after 2 to 4 wk in culture. Thereafter, the cultured cells could not grow and survive on the digested pigskin.
When 10−6
M atropine was added to the medium, amylase secretion from cultured cells and destruction of pigskin were inhibited completely
but pancreas cells could not grow or survive. In contrast, 100 μg/ml soybean trypsin inhibitor or 10−8
M atropine permitted cell growth, permitted amylase secretion from the cultured acinar cells, and prevented the destruction
of pigskin. Under these conditions pancreas cells migrated or grew or both from the organ bits onto the surface of the pigskin
dermis and organoid aggregations formed. Hydrocortisone was needed to permit growth for more than 2 wk. Glucagon and insulin
had additive effects. Light and electron microscopic observations indicated the culture of at least five kinds of cells, i.e.,
duct, acinar, centroacinar, endocrine, and mesenchymal. The majority of cultured cells were duct cells and acinar cells. There
were few mesenchymal cells. Mouse pancreas cells were cultured for at least 12 wk by this method.
This investigation was supported by PHS Grant CA 30220 awarded by the National Cancer Institute, DHHS, Grant 1203M awarded
by the Council for Tobacco Research, Inc., and Grant RD-65 (for equipment) awarded by the American Cancer Society. Nude mice
were provided by Dr. Wendall M. Farrow of Life Sciences, Inc., Resource Laboratory N01, CP6-1005 of the National Cancer Institute. 相似文献
32.
DNA-repair characteristics of xeroderma pigmentosum belonging to complementation group F were investigated. The cells exhibited an intermediate level of repair as measured in terms of (1) disappearance of T4 endonuclease-V-susceptible sites from DNA, (2) formation of ultraviolet-induced strand breaks in DNA, and (3) ultraviolet-induced unscheduled DNA synthesis during post-irradiation incubation. The impaired ability of XP3YO to perform unscheduled DNA synthesis was restored, to half the normal level, by the concomitant treatment with T4 endonuclease V and ultraviolet-inactivated Sendai virus. It is suggested that xeroderma pigmentosum cells of group F may be defective, at least in part, in the incision step of excision repair. 相似文献
33.
A useful measure of diversity was calculated for microbial communities collected from lake water and sediment samples using the Shannon index (H′) and rarefaction [E(S)]. Isolates were clustered by a numerical taxonomy approach in which limited (<20) tests were used so that the groups obtained represented a level of resolution other than species. The numerical value of diversity for each sample was affected by the number of tests used; however, the relative diversity compared among several sampling locations was the same whether 11 or 19 characters were examined. The number of isolates (i.e., sample size) strongly influenced the value of H′ so that unequal sized samples could not be compared. Rarefaction accounts for differences in sample size inherently so that such comparisons are made simple. Due to the type of sampling carried out by microbiologists, H′ is estimated and not determined and therefore requires a statement of error associated with it. Failure to report error provided potentially misleading results. Calculation of the variance of H′ is not a simple matter and may be impossible when handling a large number of samples. With rarefaction, the variance of E(S) is readily determined, facilitating the comparison of many samples. 相似文献
34.
Aaron E. Freeman Howard J. Igel Brenda J. Herrman Karen L. Kleinfeld 《In vitro cellular & developmental biology. Plant》1976,12(5):352-362
Summary In 129 of 140 attempts, human skin cells were successfully cultured on the dermal collagen bed of sterile, dead pigskin. Diploid
epithelial cells grew selectively on the collagen bed; fibroblasts grew on the glass surfaces of the culture dishes. The cultures
could be subdivided physically up to six times at a 1:2 split ratio, but at least 24 to 48 cell generations were produced
over the months the cells could be carried. Much of the cell multiplication resulted in maturation into distinct basal, squamous,
granular, and keratinized cell layers. The cultured cells were considered epithelial because of their shape, possession of
intercellular bridges, desmosomes and tonofibrils, and because they formed maturating epithelium in vitro and upon transplantation
back to the original human donor. As the cells grew they digested the pigskin collagen, thus producing clear zones that could
be used to monitor and quantitate cell growth. Multiplication of epithelial cells, rather than migration, was indicated by
mitotic figures in colchicine-treated cultures and by DNA synthesis.
Expert technical assistance was provided by Nancy Allen (cell culture); William Towler (electron microscopy); James Malone,
Nona Scaife, and Joy M. Nicolet (cytogenetics); R. Thomas Campbell and Dorothy Sarver (photography); and V. L. Angerstein,
Susan Ekker, and Arnater Yarbrough (histology).
This work was supported by The United Fund Cancer Society of Summit County, the Greater Cleveland Associated Foundation (grant
no. 3G3490X1), the National Institute of General Medical Services (grant no. 1 R01 GM 21929-01), and the Charles E. Merrill
Trust. 相似文献
35.
Three kinds of fluorescence enhancement result from the interaction of 2-p-toluidinylnaphthalene-6-sulfonate and calf-skin collagen. They are negatively cooperative, independent, and highly cooperative fluorescence enhancement. In the independent region at pH 3.7, the binding number is about 36 moles of 2-p-toluidinylnaphthalene-6-sulfonate per mole of tropocollagen with a binding constant of 2.0 × 104 M?1; with ΔG = ?5.7 kcal/mole, ΔH = ?4.0 kcal/mole, and ΔS = 6 e.u. The pH dependence of fluorescence of native collagen shows that the deprotonated forms of the β and γ carboxyl groups of aspartic and glutamic acid decrease the intensity, possibly by charge repulsion of the negatively charged sulfonate group of 2-p-toluidinylnaphthalene-6-sulfonate. The positive charge of lysine is found to be unimportant in the interaction of 2-p-toluidinylnaphthalene-6-sulfonate with collagen. Fluorescence enhancement is caused mainly by the hydrophobic interactions of 2-p-toluidinylnaphthalene-6-sulfonate and collagen. Salt bridge formation between basic and acidic side chains in very low salt concentration may be detectable by 2-p-toluidinylnaphthalene-6-sulfonate fluorescence. 相似文献
36.
O. Modesto Olanya Joseph E. Sites Aaron K. Hoshide 《Biocontrol Science and Technology》2016,26(5):651-664
Published research on process-based models for biocontrol of foodborne pathogens on produce is limited. The aim of this research was to develop cost model estimates for competitive exclusion (CE) process using Pseudomonas fluorescens and Pseudomonas chlororaphis (non-plant pathogenic and non-human pathogen) as biocontrol against Salmonella enterica on tomatoes. Cost estimates were based on material inputs, equipment, facilities, and projected processing conditions of post-harvest packaging of tomatoes. The microbiological data for inactivation of S. enterica was based on published papers. The small-scale processing facility was assumed to have a processing capacity of 2000 kg of tomatoes/hour for 16 h per day, operational 6 days a week, and for 3-months /year. The large-scale facility was assumed to have a processing capacity of 100,000 kg of tomatoes/hour. Estimated initial capital investment costs for small and large-scale models (production facility) were US$391,000 and US$2.1 million. Application of CE for biocontrol of S. enterica on tomatoes was estimated at US$0.0058–0.073/kg of tomatoes during commercial processing operations. This exceeds chlorine wash technology estimated at US$0.00046/kg and is competitive with gaseous chlorine dioxide at US$0.02–0.21/kg. For high-value produce, CE may complement existing technologies increase food safety, reduce storage loses, and extend shelf life of produce. 相似文献
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