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1.
Studies to examine the microbial fermentation of coal gasification products (CO 2, H 2 and CO) to methane have been done with a mixed culture of anaerobic bacteria selected from an anaerobic sewage digestor. The specific rate of methane production at 37°C reached 25 mmol/g cell hr. The stoichiometry for methane production was 4 mmol H 2/mol CO 2. Cell recycle was used to increase the cell concentration from 2.5 to 8.3 g/liter; the volumetric rate of methane production ran from 1.3 to 4 liter/liter hr. The biogasification was also examined at elevated pressure (450 psi) and temperature to facilitate interfacing with a coal gasifier. At 60°C, the specific rate of methane production reached 50 mmol/g cell hr. Carbon monoxide utilization by the mixed culture of anaerobes and by a Rhodopseudomonas species was examined. Both cultures are able to carry out the shift conversion of CO and water to CO 2 and hydrogen. 相似文献
2.
Cell culture experiments often employ the use of culture media that contain fetal calf serum (FCS). The angiotensin peptides
angiotensin II and angiotensin 1–7 have opposing effects with angiotensin converting enzyme 2 (ACE2) being the enzyme predominantly
responsible for generating angiotensin 1–7 from angiotensin II. The effect of FCS on angiotensin peptides has not previously
been described. We have shown that FCS has ACE2 enzyme activity capable of degrading angiotensin II and generating angiotensin
1–7. Researchers should be aware that FCS possesses ACE2 activity and that heat-treating FCS to 56 °C only partially inhibits
this enzyme activity, whereas heat-treating to 70 °C completely abolishes ACE2 activity. 相似文献
3.
A new cell line designated as BCS-TC2 was established in culture from a primary human colon adenocarcinoma. This cell line has been in continuous culture over a 36-month period. The cells grow as a monolayer sheet, displaying areas with a multilayered pattern as well as single cells and free-floating aggregates. The morphological, immunological, and ultrastructural features of these cells are in agreement with their epithelial origin. The characterization of this cell line indicated a 38 hr doubling time, and a colony forming efficiency of 2% in semisolid media and 22% in liquid culture, at low cell densities. These cells produce low amounts of carcinoembryonic antigen in culture (0.1 ng of CEA/10 6 cells). Sub-cutaneous injection into athymic mice shows that these cells have a non-tumorigenic capacity. Chromosomal analysis showed a karyotype 46 XX,-15, +der (15), inv (16) (p13::q13). BCS-TC2 cell line, which maintains in culture several characteristics of the original tumor, represents a useful model system for cell biology studies of primary and non-metastatic tumors. 相似文献
4.
Summary Although Caco-2 cells are frequently employed for the study of enterocyte lipid metabolism, variable results have been reported
regarding their ability to synthesize and secrete lipids and apolipoproteins. The major goal of this investigation is to examine
the capacity of Caco-2 cells to elaborate and secrete lipids, lipoproteins, and apolipoproteins at different degrees of morphological
and functional differentiation. Cells were cultured in medium with 5% fetal bovine serum (FBS), on permeable polycarbonate
filters from 2 to 30 d in the presence of 14C-oleate or 35S-methionine. Cellular differentiation, as assessed by morphology (light and electron microscopy), transepithelial resistance,
free fatty acid flux, and sucrase activity, progressed steadily up to 20 d of culture. Caco-2 cells esterified oleic acid
mainly into phospholipids, triglycerides (TG), and smaller amounts of cholesterol esters. Lipid synthesis began as early as
2 d, and TG secretion was enhanced with increased duration of culture. However, very low efficiency of lipid export was observed
at all levels of differentiation, reaching a maximum of only 6% of intracellular lipids. VLDL and LDL were the dominant lipoproteins
secreted, with HDL comprising <20% of the total. VLDL secretion increased, while LDL decreased, whereas the lipid composition
of lipoproteins varied little with increasing duration of culture. Apoprotein B and A-I synthesis and secretion increased
markedly from 11 to 20 d of culture. The ratio of apo B-100/B-48 decreased between 11 and 30 d, consistent with enhanced apo
B editing of more mature enterocytes. Taken together, our data suggest that from 20 d of culture, Caco-2 cells are morphologically
and functionally mature, capable of lipid esterification, and lipoprotein and apolipoprotein synthesis. However, despite their
functional and morphological similarities to mature enterocytes, Caco-2 cells have a very limited lipid export capacity. 相似文献
5.
Abstract Humans have utilised plant derived natural products as medicines for millenia. Moreover, many contemporary pharmaceuticals are also natural products or derivatives thereof. However, the full potential of these compounds remains to be exploited because often they are: complex and difficult to synthesise; found in low quantities; produced by undomesticated and sometimes rare plants; and, their synthesis is routinely influenced by weather conditions. Potentially, the in vitro culture of cells from the corresponding plant species could circumvent some of these problems but the growth of plant cells on an industrial scale is also problematic. The recent isolation and culture of cambial meristematic cells (CMCs), stem cells which ordinarily generate the plant vasculature, may now provide a key platform technology to help realise the full potential of plant natural products. 相似文献
6.
The initial attachment of mesenchymal stem cells (MSCs) to substrates and osteogenic differentiation are supported by culture on a hydroxyapatite substrate. Cell attachment areas of rat MSCs after 2 h of culture on hydroxyapatite substrates with various microstructures and the osteogenic differentiation activity thereafter were measured. The perceived outcome was that, after 2 h of culture, rat MSCs with a small attachment area would have a high osteogenic differentiation activity, whereas those with a large attachment area would have a low osteogenic differentiation activity. Furthermore, rat MSCs with a small attachment area had many cytoplasmic processes, while those with a large attachment area revealed clear stress fibers and focal contacts. These results suggest that cell attachment area of rat MSCs after 2 h of culture has a strong effect on the osteogenic differentiation of rat MSCs. Thus, the measurement of cell attachment area after 2 h of culture could become valuable for estimating the osteogenic differentiation activity of rat MSCs thereafter. 相似文献
7.
Two thin layer culture units operated as batch cultures with the alga Chlorella kessleri were used in gas exchange experiments. The mass transfer coefficient K g [g m –2 h –1 kPa –1] of O 2 and CO 2 desorption from culture surface decreased with increasing culture temperature. Between 60–70% of supplied CO 2 was used for algal growth. It was estimated that the length of growth surface may be extended to about 50 m, without additional saturation by CO 2. On average 1.35 g CO 2 was consumed by the alga per 1 g of produced O 2. Net CO 2 consumption (R CO2) and O 2 production (R O2) were not inhibited by irradiance. R O2 did not decrease (in some cases it even increased) along the culture surface, despite increased accumulation of O 2. Measurement of pO 2 where the culture leaves the reactor before being pumped back onto the illuminated surface, correlated with O 2 production and CO 2 consumption and may be used to monitor the reactors growth performance. 相似文献
8.
Abstract Several sugar-modified 2-( p-n-butylanilino)-2′-deoxyadenosine analogues, including arabino and 2′( R)-azido-2′-deoxy analogues and their 5′-triphosphates were synthesized. These nucleosides thus obtained exhibited moderate cytotoxicity against P-388 leukemic cells in culture (IC 50 = 13–24 μ). In contrast to above results, the 5′-triphosphates have been shown to exert strong and selective inhibitory effects on mammalian DNA polymerase α ( Ki= 0.02–0.04 μ). 相似文献
9.
We have been studying an anaerobic enrichment culture which, by using methanol as an electron donor, dechlorinates tetrachloroethene (PCE) to vinyl chloride and ethene. Our previous results indicated that H2 was the direct electron donor for rductive dechlorination of PCE by the methanol-PCE culture. Most-probable-number counts performed on this culture indicated low numbers (< or equal to 10(4)/ml)) of methanogens and PCE dechlorinators using methanol and high numbers (> or equal to 10(6)/ml)) of sulfidogens, methanol-utilizing acetogens, fermentative heterotrophs, and PCE dechlorinators using H2. An anaerobic H2-PCE enrichment culture was derived from a 10(-6) dilution of the methanol-PCE culture. This H2-PCE culture used PCE at increasing rates over time when transferred to fresh medium and could be transferred indefinitely with H2 as the electron donor for the PCE dechlorination, indicating that H2-PCE can serve as an electron donor-acceptor pair for energy conservation and growth. Sustained PCE dechlorination by this culture was supported by supplementation with 0.05 mg of vitamin B12 per liter, 25% (vol/vol) anaerobic digestor sludge supernatant, and 2 mM acetate, which presumably served as a carbon source. Neither methanol nor acetate could serve as an electron donor for dechlorination by the H2-PCE culture, and it did not produce CH4 or acetate from H2-CO2 or methanol, indicating the absence of methanogenic and acetogenic bacteria. Microscopic observatios of the pruified H2-PCE culture showed only two major morphotypes: irregular cocci and small rods. 相似文献
10.
Biosynthesis of trichothecenes by strains of F. sporotriahioides KF 9 6 and KF 530 was performed on rice as a medium. Three toxins in significant amounts were produced, with yield: T-2 toxin 0.7g from 600g of drv culture, being the highest of the three metabolites, HT-2 toxin 0.06g an Neosolaniol 0.015g. Toxins were extracted with methanol from ground and defatted dry culture. Liquid/liquid partition, using chloroform/water saturated solution of sodium bicarbonate as a preliminary purification was applied. Silicagel and charcoal columns were used in further purification. Toxin were separated by preparative TLC and crystallized from methanol. 相似文献
11.
Voltage-gated Ca 2+ channels (VGCCs) are key regulators of many neuronal functions, and involved in multiple central nervous system diseases.
In the last 30 years, a large number of injury and disease models have been established based on cultured neurons. Culture
with serum develops a mixture of neurons and glial cells, while culture without serum develops pure neurons. Both of these
neuronal-culture methods are widely used. However, the properties of Ca 2+ currents in neurons from these two cultures have not been compared. In this study, we cultured rat cortical neurons in serum-containing
or -free medium and then recorded the Ca 2+ channel currents using patch-clamp technique. Our results showed that there were significant differences in the amplitude
and activation properties of whole-cell Ca 2+ channel currents, and of non-L-type Ca 2+ channel currents between the neurons from these two culture systems. Our data suggested that the difference of whole-cell
Ca 2+ currents may result from the differences in non-L-type currents. Understanding of these properties will considerably advance
studies of VGCCs in neurons from pure or mixed culture. 相似文献
12.
Pacemaker cells residing in the sinoatrial node generate the regular heartbeat. Ca 2+ signaling controls the heartbeat rate—directly, through the effect on membrane molecules (NCX exchange, K + channel), and indirectly, through activation of calmodulin-AC-cAMP-PKA signaling. Thus, the physiological role of signaling in pacemaker cells can only be assessed if the Ca 2+ dynamics are in the physiological range. Cultured cells that can be genetically manipulated and/or virally infected with probes are required for this purpose. Because rabbit pacemaker cells in culture experience a decrease in their spontaneous action potential (AP) firing rate below the physiological range, Ca 2+ dynamics are expected to be affected. However, Ca 2+ dynamics in cultured pacemaker cells have not been reported before. We aim to a develop a modified culture method that sustains the global and local Ca 2+ kinetics along with the AP firing rate of rabbit pacemaker cells.We used experimental and computational tools to test the viability of rabbit pacemaker cells in culture under various conditions. We tested the effect of culture dish coating, pH, phosphorylation, and energy balance on cultured rabbit pacemaker cells function. The cells were maintained in culture for 48 h in two types of culture media: one without the addition of a contraction uncoupler and one enriched with either 10 mM BDM (2,3-Butanedione 2-monoxime) or 25 μM blebbistatin. The uncoupler was washed out from the medium prior to the experiments. Cells were successfully infected with a GFP adenovirus cultured with either BDM or blebbistatin. Using either uncoupler during culture led to the cell surface area being maintained at the same level as fresh cells. Moreover, the phospholamban and ryanodine receptor densities and their phosphorylation level remained intact in culture when either blebbistatin or BDM were present. Spontaneous AP firing rate, spontaneous Ca 2+ kinetics, and spontaneous local Ca 2+ release parameters were similar in the cultured cells with blebbistatin as in fresh cells. However, BDM affects these parameters. Using experimental and a computational model, we showed that by eliminating contraction, phosphorylation activity is preserved and energy is reduced. However, the side-effects of BDM render it less effective than blebbistatin. 相似文献
13.
Adenovirus-mediated gene transfer into adult cardiac myocytes in primary culture is a potentially useful method to study the structure and function of the contractile apparatus. However, the consequences of adenovirus infection on the highly differentiated state of the cultured myocyte have not been determined. We report here a detailed analysis of myofilament structure and function over time in primary culture and after adenovirus infection. Adult rat ventricular myocytes in primary culture were infected with a recombinant adenovirus vector expressing either the LacZ or alkaline phosphatase reporter gene. Control and infected myocytes were collected at days 0-7 post-isolation/infection, and myofilament isoform expression was determined by SDS-PAGE and Western blot. Laser scanning densitometry showed that the - to -myosin heavy chain ratio, the stoichiometry of the myosin light chains and the expression of the adult troponin T isoform did not change over time in culture or with adenovinus treatment. Importantly, examination of Ca 2+-activated tension in single myocytes showed no change in the shape or position of the tension-pCa relationship in the control and adenovirus infected myocytes during primary culture. These results indicate that the structure and function of adult cardiac myocytes are stable in short term primary culture and are not affected by adenovirus infection per se, and therefore provide the foundation for the use of adenovirus-mediated myofilament gene transfer to study contractile apparatus structure and function in adult cardiac myocytes.ain. 相似文献
14.
Modifications at C-3 and C-4 of 2-amino-2-deoxy-d-glucose have been developed. A 3,4-double bond was introduced into benzyl 2-acetamido-2-deoxy-3,4-di- O-Methylsulfonyl-α-d-glucopyranoside by treatment with NaI and Zn. Epoxidation of the double bond with m-chloroperoxybenzoic acid gave an exo-epoxide exclusively. The stereochemistry of the epoxidation product has been confirmed by an alternative synthesis. An analysis of the 1H-n.m.r. spectra indicates that both the 3,4-unsaturated derivatives and the epoxide exist in the ° H1 (d) conformation. Nucleophilic reagents (F ?, I ?) opened the 3,4-epoxide to give 4-substituted derivatives having the d- gulo configuration. Thus, 2-acetamido-1,3,6-tri- O-acetyl-2,4-dideoxy-4-iodo-α-d-gulopyranose and 2-acetamido-1,3,6-tri- O-acetyl-3,4-dideoxy-4-fluoro-α-d-gulopyranose have been synthesized. Reduction of the double bond in the key intermediate and deprotection gave 2-acetamido-2,3,4-trideoxy-d-glucopyranose. Some of the derivatives were active as inhibitors of growth of mouse, mammary adenocarcinoma cells in culture. 相似文献
15.
Due to a poor clinical predictive power of 2D cell cultures, standard tool for in vitro assays in drug discovery process, there is increasing interest in developing 3D in vitro cell cultures, biologically relevant assay feasible for the development of robust preclinical anti-cancer drug screening platforms. Herein, we tested amidino-substituted benzimidazoles and benzimidazo[1,2- a]quinolines as a small platform for comparison of antitumor activity in 2D and 3D cell culture systems and correlation with structure–activity relationship. 3D cell culture method was applied on a human cancer breast (SK-BR-3, MDA-MB-231, T-47D) and pancreatic cancer cells (MIA PaCa-2, PANC-1). Results obtained in 2D and 3D models were highly comparable, but in some cases we have observed significant disagreement indicating that some prominent compounds can be discarded in early phase of researching because of compounds with false positive result. To confirm which of cell culture systems is more accurate, in vivo profiling is needed. 相似文献
16.
A prokaryotic expression system has been used to produce recombinant human bone morphogenetic protein-2 (rhBMP-2). However,
low rhBMP-2 yields and protein loss during purification and renaturation are the hurdles in the clinical application. Previous
studies have indicated that variables such as temperature, host cell, salt concentration, and culture time affect the final
rhBMP-2 yield. The optimization of these conditions in an Escherichia coli culture yielded 28.258 mg of rhBMP-2 per liter of culture. To reduce rhBMP-2 loss during purification and renaturation, we
performed purification before renaturation in the prokaryotic expression system instead of using the traditional renaturation-before-purification
approach. rhBMP-2 was separated on a Sephacryl S-300 HR column and eluted from a DEAE-Sepharose Fast Flow column. The collected
protein was refolded by dialysis with urea buffer, which was followed by dialysis with ultrapure water. The purified rhBMP-2
dimer significantly increased alkaline phosphatase (ALP) activity and osteogenic activity in the femoral muscle and showed
the same level of bone-forming activity as natural BMP-2. This optimized procedure for expression and renaturation of rhBMP-2
has potential clinical applications. 相似文献
17.
The determination of dissolved CO(2) and HCO(3)(-) concentrations as well as the carbon dioxide production rate in mammalian cell suspension culture is attracting more and more attention since the effects on major cell properties, such as cell growth rate, product quality/production rate, intracellular pH and apoptosis, have been revealed. But the determination of these parameters by gas analysis is complicated by the solution/dissolution of carbon dioxide in the culture medium. This means that the carbon dioxide transfer rate (CTR; which can easily be calculated from off-gas measurement) is not necessarily equal to carbon dioxide production rate (CPR). In this paper, a mathematical method to utilize off-gas measurement and culture pH for cell suspension culture is presented. The method takes pH changes, buffer and medium characteristics that effect CO(2) mass transfer into account. These calculations, based on a profound set of equations, allow the determination of the respiratory activity of the cells, as well as the determination of dissolved CO(2), HCO(3)(-) and total dissolved carbonate. The method is illustrated by application to experimental data. The calculated dissolved CO(2) concentrations are compared with measurements from an electrochemical CO(2) probe. 相似文献
18.
Several recent studies have suggested seemingly contrasting roles of SIRT2 in inflammation: Our previous cell culture study has indicated that SIRT2 siRNA-produced decrease in SIRT2 levels can lead to significant inhibition of lipopolysaccharides (LPS)-induced activation of BV2 microglia, suggesting that SIRT2 is required for LPS-induced microglial activation. In contrast, some studies have suggested that SIRT2 deficiency can lead to increased inflammation. In our current study, we used a mouse model of neuroinflammation to determine the roles of SIRT2 in LPS-induced inflammation. We found that administration of SIRT2 inhibitor AGK2 can significantly decrease LPS-induced increases in CD11b signals and the mRNA of TNF-α and IL-6. We further found that AGK2 can block LPS-induced nuclear translocation of NFκB. In addition, our study has shown that AGK2 can decrease not only LPS-induced increase in TUNEL signals—a marker of apoptosis-like damage, but also LPS-induced increases in the levels of active Caspase-3 and Bax. Collectively, our current in vivo study, together with our previous cell culture study, has suggested that SIRT2 is required for LPS-induced neuroinflammation and brain injury. 相似文献
19.
Technologies for in vitro embryo production have the potential to enhance the efficiency of cattle production systems. However, utilization of in vitro-produced embryos for transfer remains limited throughout much of the world. Despite improvements over the past two decades, problems associated with the production of bovine embryos in vitro still exist which limit the widespread commercial application of this technology. In particular, bovine embryos produced in vitro have a reduced capacity to establish and maintain pregnancy as compared with their in vivo-derived counterparts. Embryo competence for survival following transfer is improved by in vivo culture in the sheep oviduct, thus indicating that standard embryo culture conditions are sub-optimal. Therefore, one strategy to improve post-transfer survival is to modify embryo culture media to more closely mimic the in vivo microenvironment. The maternal environment in which the bovine embryo develops in vivo contains various growth factors, cytokines, hormones, and other regulatory molecules. In addition to affecting bovine embryo development in vitro, recent research indicates that embryo competence for survival following transfer can also be improved when such molecules are added to embryo culture medium. Among the specific molecules that can increase post-transfer embryo survival are insulin-like growth factor-1 (IGF-1), colony stimulating factor-2 (CSF-2) and hyaluronan. This paper will review the effects IGF-1, CSF-2 and hyaluronan on post-culture embryo viability and discuss the potential mechanisms through which each of these molecules improves post-transfer survival. 相似文献
20.
AbstractLong-term coordinated regulations (during development or by agonists and second messenger molecules) of the expression of mRNAs encoding D2-dopamine (DA) receptors and D2 receptor-linked Goα proteins have been studied by Northern blot analysis in mouse embryonic striatal neurones in primary culture. During the course of the cell culture, the levels of both mRNAs increased, in conjunction with the maturation of the neurones. When the preparation was treated with the D2-DA agonist quinpirole (5–15 hrs, 10 ?4 M), which decreases cAMP in these neurones, the levels of Goα mRNAs were enhanced whereas that of the D2 mRNA remained unchanged. Conversely, the Goα mRNAs, but not the D2 mRNA, decreased when the neurones were exposed to 8-bromo-cAMP (16 hrs, 10 ?6 M). It is concluded that, in these experimental conditions where neurones have not yet established their connexions, the long-term regulation of the membrane transmission of D2-DA signal might implicate mainly the Goα encoding gene. 相似文献
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