scholarly journals Stability of a biodegradable microcarrier surface: physically adsorbed versus chemically linked shells

2018 ◽  
Vol 6 (31) ◽  
pp. 5130-5143 ◽  
Author(s):  
Audrey Roy ◽  
Maria Alejandra Murcia Valderrama ◽  
Valentin Daujat ◽  
Khalid Ferji ◽  
Michèle Léonard ◽  
...  
Keyword(s):  
Culture Medium ◽  
Shell Stability

Microcarriers' shell stability was studied with competitive surfactants or with proteins contained in the MSCs culture medium.

Effect of Some Metabolic Inhibitors on Vinblastine-Induced Ribosomal-Granular Material Complexes

1971 ◽  
Vol 29 ◽  
pp. 548-549
Author(s):  
Awtar Krishan ◽  
Dora Hsu
Keyword(s):  
Granular Material ◽  
Rna Synthesis ◽  
Culture Medium ◽  
Actinomycin D ◽  
Metabolic Inhibitors ◽  
Protein And Rna Synthesis ◽  
Apparent Reduction ◽  
Plant Alkaloids ◽  
In Cells

Cells exposed to antitumor plant alkaloids, vinblastine and vincristine sulfate have large proteinacious crystals and complexes of ribosomes, helical polyribosomes and electron-dense granular material (ribosomal complexes) in their cytoplasm, Binding of H3-colchicine by the in vivo crystals shows that they contain microtubular proteins. Association of ribosomal complexes with the crystals suggests that these structures may be interrelated.In the present study cultured human leukemic lymphoblasts (CCRF-CEM), were incubated with protein and RNA-synthesis inhibitors, p. fluorophenylalanine, puromycin, cycloheximide or actinomycin-D before the addition of crystal-inducing doses of vinblastine to the culture medium. None of these compounds could completely prevent the formation of the ribosomal complexes or the crystals. However, in cells pre-incubated with puromycin, cycloheximide, or actinomycin-D, a reduction in the number and size of the ribosomal complexes was seen. Large helical polyribosomes were absent in the ribosomal complexes of cells treated with puromycin, while in cells exposed to cycloheximide, there was an apparent reduction in the number of ribosomes associated with the ribosomal complexes (Fig. 2).

Structural aspects of osmoregulation in porphyra

1978 ◽  
Vol 36 (2) ◽  
pp. 412-413
Author(s):  
C. Wiencke ◽  
A. Lauchli
Keyword(s):  
Culture Medium ◽  
Point Of View ◽  
Chemical Fixation ◽  
Cellular Organization ◽  
Osmotic Adaptation ◽  
Osmotic Balance ◽  
Activity Of Enzymes ◽  
Osmotic Agents ◽  
Vacuolar System ◽  
Structural Aspects

Osmoregulatory mechanisms in algae were investigated mainly from a physiological point of view (KAUSS 1977, HELLEBUST 1976). In Porphyra two osmotic agents, i. e. floridoside/isofloridoside (KAUSS 1968) and certain ions, such as K+ and Na+(EPPLEY et al. 1960) are considered for osmotic balance. Accumulations of ions (particularly Na+) in the cytoplasm during osmotic adaptation is improbable, because the activity of enzymes is generally inhibited by high ionic concentrations (FLOWERS et al. 1977).The cellular organization of Porphyra was studied with special emphasis on the development of the vacuolar system under different hyperosmotic conditions. Porphyra was cultivated at various strengths of the culture medium ASP 12 (PROVASOLI 1961) ranging from normal to 6 times concentrated (6x) culture medium. Por electron microscopy freeze fracturing was used (specimens fixed in 2% glutaraldehyde and incubated in 30% glycerol, preparation in a BALZERS BA 360 M apparatus), because chemical fixation gave poor results.

The significance of SEM in the diagnosis of haematopoietic malignancies

1978 ◽  
Vol 36 (2) ◽  
pp. 314-315
Author(s):  
Etienne de Harven ◽  
Nina Lampen
Keyword(s):  
Room Temperature ◽  
Culture Medium ◽  
Cell Attachment ◽  
Ethanol Dehydration ◽  
Moist Chamber ◽  
Efficient Alternative ◽  
Mononuclear Leucocytes ◽  
Fast Quenching ◽  
Freeze Dryer ◽  
Scanning Electron

Samples of heparinized blood, or bone marrow aspirates, or cell suspensions prepared from biopsied tissues (nodes, spleen, etc. ) are routinely prepared, after Ficoll-Hypaque concentration of the mononuclear leucocytes, for scanning electron microscopy. One drop of the cell suspension is placed in a moist chamber on a poly-l-lysine pretreated plastic coverslip (Mazia et al., J. Cell Biol. 66:198-199, 1975) and fifteen minutes allowed for cell attachment. Fixation, started in 2. 5% glutaraldehyde in culture medium at room temperature for 30 minutes, is continued in the same fixative at 4°C overnight or longer. Ethanol dehydration is immediately followed by drying at the critical point of CO2 or of Freon 13. An efficient alternative method for ethanol dehydrated cells is to dry the cells at low temperature (-75°C) under vacuum (10-2 Torr) for 30 minutes in an Edwards-Pearse freeze-dryer (de Harven et al., SEM/IITRI/1977, 519-524). This is preceded by fast quenching in supercooled ethanol (between -90 and -100°C).

TEM study of a biofilm on copper corrosion

1996 ◽  
Vol 54 ◽  
pp. 220-221
Author(s):  
W. A. Chiou ◽  
N. Kohyama ◽  
B. Little ◽  
P. Wagner ◽  
M. Meshii
Keyword(s):  
Marine Bacterium ◽  
Culture Medium ◽  
Copper Alloys ◽  
Pure Copper ◽  
Localized Corrosion ◽  
Natural Seawater ◽  
Copper Corrosion ◽  
New Approach ◽  
The Past ◽  
Copper Tolerant

The corrosion of copper and copper alloys in a marine environment is of great concern because of their widespread use in heat exchangers and steam condensers in which natural seawater is the coolant. It has become increasingly evident that microorganisms play an important role in the corrosion of a number of metals and alloys under a variety of environments. For the past 15 years the use of SEM has proven to be useful in studying biofilms and spatial relationships between bacteria and localized corrosion of metals. Little information, however, has been obtained using TEM capitalizing on its higher spacial resolution and the transmission observation of interfaces. The research presented herein is the first step of this new approach in studying the corrosion with biological influence in pure copper.Commercially produced copper (Cu, 99%) foils of approximately 120 μm thick exposed to a copper-tolerant marine bacterium, Oceanospirillum, and an abiotic culture medium were subsampled (1 cm × 1 cm) for this study along with unexposed control samples.

Involvement of nucleus in the maturation of dengue-2 virus in C6/36 cells

1990 ◽  
Vol 48 (3) ◽  
pp. 912-913
Author(s):  
Jaang J. Wang ◽  
Cheng C. Chen ◽  
Men F. Shaio ◽  
Chia T. Liu ◽  
Chung S. Lee ◽  
...  
Keyword(s):  
Culture Medium ◽  
Cytopathic Effect ◽  
Fetal Bovine Serum ◽  
Virus Particles ◽  
Electron Microscopies ◽  
Embedding Technique ◽  
Fetal Bovine ◽  
Flat Embedding ◽  
20 Nm ◽  
Labeling Method

The involvement of nucleus in the maturation processes of Dengue-2 virus in a mosquito cell line, C6/36 cells, has been identified by the electron microscopy and immunocytochemistry. The C6/36 cells were obtained from ATCC and maintained in MEM culture medium containing 10% fetal bovine serum at 28°C. The cell suspensions or cells grown on teflon-coated coverslips were infected with Dengue-2 virus (107/ml) for various time periods of 2 hours, 3, 6, 8, and 10 days. The cells were then fixed in buffered 1.5% glutaraldehyde, and washed in acetone before immunolabeled with monoclonal antibody. An indirect immunocytochemical labeling method of avidin-biotin complex (ABC) conjugated with peroxidase or gold particles (20 nm in diameter) and a flat embedding technique were used to localize the virus particles.At early stages of infections (before 3 days), there were no virion particles detected. After 6 days and on of infections, cytopathic effect (CPE) was observed and showed positive immuno-peroxidase reactions under the light and electron microscopies.

Fibrillin molecules aggregate to form an extendible beaded structure which is a major component of “Elastin Associated” microfibrils

1989 ◽  
Vol 47 ◽  
pp. 246-247
Author(s):  
Douglas R. Keene ◽  
B. Kerry Maddox ◽  
Marie B. Spurgin ◽  
Lynn Y. Sakai ◽  
Robert W. Glanville
Keyword(s):  
Molecular Sieve ◽  
Room Temperature ◽  
Culture Medium ◽  
Weight Fraction ◽  
Ammonium Bicarbonate ◽  
High Molecular Weight Fraction ◽  
Bicarbonate Buffer ◽  
Human Amnion ◽  
Gold Conjugate ◽  
Ammonium Bicarbonate Buffer

A mouse monoclonal antibody was used to identify beaded aggregates found in guanidine extracts of human amnion as assemblies of fibrillin molecules. These aggregates were also shown to be a major component of extracellular matrix microfibrils. We further demonstrated that the periodicity of these aggregates can be increased when subjected to mechanical stress.Human amnion was extracted with guanidine and the extracted material purified using ion exchange and molecular sieve chromatography. A high molecular weight fraction was precipitated by dialyzing against dilute acetic acid. Part of the precipitate was suspended in 0.2 M ammonium bicarbonate buffer and rotary shadowed. A second portion was resuspended in culture medium containing antibody which recognizes matrix microfibrils, diluted 1:5 in ammonium bicarbonate and reacted for 120 minutes at room temperature. Antibody labeled precipitate was washed by repeated pelleting and resuspension in buffer and then incubated in Janssen GAM 5 nm gold conjugate for 60 minutes at room temperature.

HVEM Cryomicroscopy of Frozen Hydrated PTK1 Cells

1990 ◽  
Vol 48 (1) ◽  
pp. 500-501
Author(s):  
E.T. O’Toole ◽  
G.P. Wray ◽  
J.R. Kremer ◽  
J.R. Mcintosh
Keyword(s):  
Liquid Nitrogen ◽  
Phase Contrast ◽  
Culture Medium ◽  
Low Dose ◽  
Ammonium Acetate ◽  
Freezing Point ◽  
Voltage Electron ◽  
Cold Stage ◽  
Humidity Chamber ◽  
Coated Carbon

Ultrarapid freezing and cryomicroscopy of frozen hydrated material makes it possible to visualize samples that have never been exposed to chemical fixatives, dehydration, or stains. In principle, freezing and cryoimaging methods avoid artifacts associated with chemical fixation and processing and allow one to visualize the specimen in a condition that is close to its native state. Here we describe a way to use a high voltage electron microscope (HVEM) for the cryoimaging of frozen hydrated PTK1 cells.PTK1 cells were cultured on formvar-coated, carbon stabilized gold grids. After three days in culture, the grids were removed from the culture medium and blotted in a humidity chamber at 35° C. In some instances, the grids were rinsed briefly in 0.16 M ammonium acetate buffer (pH 7.2) prior to blotting. After blotting, the grids were transferred to a plunging apparatus and plunged into liquid ethane held directly above its freezing point. The plunging apparatus consists of a vertical slide rail that guides the fall of a mounted pair of forceps that clamp the specimen. The forceps are surrounded by a plexiglass humidity chamber mounted over a dewar of liquid nitrogen containing an ethane chamber. After freezing, the samples were transferred to liquid nitrogen and viewed in a JEOL JEM 1000 equipped with a top entry cold stage designed and built by Mr. George Wray (Univ. Colorado). The samples were routinely exposed to electron doses of 1 e/Å2/sec, and viewed at a temperature of −150° C. A GATAN video system was used to enhance contrast and to estimate the correct amount of underfocus needed to obtain phase contrast at various magnifications. Low dose micrographs were taken using two second exposures of Kodak 4463 film. The state of the solid water in the specimen was determined by diffraction using a 30/μm field limiting aperture and a camera length of 1 meter.

The Influence of Insulin, ß-Estradiol, Dexamethasone and Thyroid Hormone on the Secretion of Coagulant and Anticoagulant Proteins by HepG2 Cells

1995 ◽  
Vol 74 (02) ◽  
pp. 686-692 ◽  
Author(s):  
René W L M Niessen ◽  
Birgit A Pfaffendorf ◽  
Augueste Sturk ◽  
Roy J Lamping ◽  
Marianne C L Schaap ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Protein C ◽  
Protein Production ◽  
Culture Medium ◽  
Protein S ◽  
Cell Protein ◽  
Hepatoma Cell Line ◽  
Factor X ◽  
Factor Ii ◽  
At Iii

SummaryAs a basis for regulatory studies on the influence of hormones on (anti)coagulant protein production by hepatocytes, we examined the amounts of the plasma proteins antithrombin III (AT III), protein C, protein S, factor II, factor X, fibrinogen, and prealbumin produced by the hepatoma cell line HepG2, into the culture medium, in the absence and presence of insulin, β-estradiol, dexamethasone and thyroid hormone. Without hormones these cells produced large amounts of fibrinogen (2,452 ± 501 ng/mg cell protein), AT III (447 ± 16 ng/mg cell protein) and factor II (464 ± 31 ng/mg cell protein) and only small amounts of protein C (50 ± 7 ng/mg cell protein) and factor X (55 ± 5 ng/mg cell protein). Thyroid hormone had a slight but significant effect on the enrichment in the culture medium of the anticoagulant protein AT III (1.34-fold) but not on protein C (0.96-fold) and protein S (0.91-fold). This hormone also significantly increased the amounts of the coagulant proteins factor II (1.28-fold), factor X (1.45-fold) and fibrinogen (2.17-fold). Insulin had an overall stimulating effect on the amounts of all the proteins that were investigated. Neither dexamethasone nor ß-estradiol administration did substantially change the amounts of these proteins.We conclude that the HepG2 cell is a useful tool to study the hormonal regulation of the production of (anti)coagulant proteins. We studied the overall process of protein production, i.e., the amounts of proteins produced into the culture medium. Detailed studies have to be performed to establish the specific hormonal effects on the underlying processes, e.g., transcription, translation, cellular processing and transport, and secretion.

A technique for superfusion of isolated granulosa cells. Dynamics of cAMP production and steroidogenesis in response to gonadotropins

1988 ◽  
Vol 117 (4) ◽  
pp. 497-506 ◽  
Author(s):  
Carl Johanson ◽  
Viktor Johanson
Keyword(s):  
Granulosa Cells ◽  
Culture Medium ◽  
Cell Damage ◽  
Adenosine Monophosphate ◽  
Camp Production ◽  
Morphological Examination ◽  
Ovarian Cells ◽  
Temporal Relationships ◽  
Polycarbonate Membranes ◽  
Estradiol 17Β

Abstract. A superfusion model for isolated ovarian cells was developed and characterized in detail. Granulosa cells isolated from pre-ovulatory rat ovarian follicles were placed in superfusion (perifusion) chambers with a volume of 125 μl. Culture medium was pumped through the chambers, collected in 20-min fractions of 600 μl and analysed for cAMP and steroids. Viability was confirmed by morphological examination. The use of polycarbonate membranes to retain the cells in the chambers was abandoned since the membranes caused severe cell damage. The temporal relationships between gonadotropic stimuli and the release of cyclic 3':5'-adenosine monophosphate (cAMP) and steroids was investigated. Within 10 min FSH elicited transient increase in the release of cAMP and progesterone but had no effect on testosterone or estradiol-17β release. Amplitude and duration of the response in cAMP and progesterone release were correlated to concentration and length of the FSH pulse when these parameters were varied within the ranges 1–100 μg/l and 30–270 min, respectively. Compared with the cAMP response, the progesterone response peaked up to 30 min later and lasted 1 to 2 h longer but could not be extended to more than approximately 6 h, not even with longer FSH pulses. These results could indicate a development of desensitization.

Follicle-stimulating hormone-dependent estrogen secretion by rat Sertoli cells in vitro: Modulation by calcium

1991 ◽  
Vol 125 (3) ◽  
pp. 280-285 ◽  
Author(s):  
J. Alan Talbot ◽  
Ann Lambert ◽  
Robert Mitchell ◽  
Marek Grabinski ◽  
David C. Anderson ◽  
...  
Keyword(s):  
Sertoli Cells ◽  
Culture Medium ◽  
Follicle Stimulating Hormone ◽  
Dibutyryl Camp ◽  
Immature Rat ◽  
Estradiol Secretion ◽  
Old Rats ◽  
Stimulating Hormone

Abstract We have investigated the role of Ca2+ in the control of FSH-induced estradiol secretion by Sertoli cells isolated from 8-10 days old rats. Exogenous Ca2+ (4-8 mmol/1) inhibited FSH-stimulated E2 secretion such that, with 8 mmol/l Ca2+ and FSH (8 IU/l) E2 secretion decreased from 2091±322 to 1480±84 pmol/l (p<0.002), whilst chelation of Ca2+ in the culture medium with EGTA (3 mmol/l) increased E2 secretion from 360±45 to 1242±133 pmol/l) in the absence of FSH. Further, EGTA (3 mmol/l) markedly potentiated FSH (8 IU/l), forskolin (1 μmol/l) and dibutyryl cAMP (1 mmol/l)-stimulated E2 secretion. Addition of the Ca2+ ionophores, ionomycin (2-5 μmol/l) and A23187 (2 μmol/l), inhibited FSH (8 IU/l)-stimulated E2 secretion by >80%. The effect of ionomycin was totally reversible, whereas that of A23187 was irreversible. Ionomycin (5 μmol/l) had no effect on EGTA-induced E2 secretion in the absence of FSH, but reduced EGTA-provoked E2 secretion by 59% in the presence of FSH (8 IU/l). Similarly, forskolin- and dibutyryl cAMP-provoked E2 production was inhibited 46-50% by ionomycin (5 μmol/l). We conclude that FSH-induced E2 secretion from immature rat Sertoli cells is modulated by intra- and extracellular Ca2+.

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