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PubMed2000

Chondrocyte transplantation for osteochondral defects with the use of suspension culture.

Cartilage graft is considered to be useful in repairing chondral or osteochondral defects. One method of the cartilage graft is achieved by autologous chondrocyte transplantation following cell culture. However, chondrocytes change their phenotype during culture. We used costal chondrocytes cultured over agarose (suspension culture) as a source of graft materials. The suspension-cultured chondrocytes formed aggregate in culture. We first examined the expressions of cartilage-specific matrices of cultured chondrocytes after two weeks in culture. The chondrocytes cultured over agarose expressed more type II collagen mRNA than those cultured on plastic dishes did after two weeks in culture. Safranin O staining showed the presence of glycosaminoglycans in the chondrocyte culture over agarose, while glycosaminoglycans were not observed in the culture on plastic dishes. We then examined the changes of rat articular osteochondral defects after transplantation of suspension-cultured chondrocytes. The aggregate of suspension-cultured chondrocytes was easily picked up with forceps and transplanted in the osteochondral defects. The defects were filled with safranin O-stained hyaline cartilage tissue two weeks after chondrocyte transplantation. On the contrary, the fibrous materials, which were not stained with safranin O, were observed in the control defects. These results suggest that the suspension-cultured chondrocytes are useful for autologous cartilage grafts by preserving chondrocyte phenotype.

Journal Article↗
PubMed2005

The complex phase behaviour of suspensions of goethite (alpha-FeOOH) nanorods in a magnetic field.

In 1902, Majorana reported the magneto-optical properties of aqueous colloidal suspensions of mixed iron oxides. Oddly enough, the magnetic-field induced birefringence displayed a non-monotonic dependence upon field intensity. This behaviour was later interpreted as due to the existence in these sols of at least two different chemical species. During the course of our studies of mineral liquid crystals, we have revisited this problem by examining aqueous suspensions of pure goethite (alpha-FeOOH) nanorods. Although they are comprised of a single chemical species, these suspensions show the same odd behaviour reported by Majorana. Moreover, we show that, as the volume fraction increases, the suspensions have an isotropic liquid/nematic/rectangular columnar phase sequence, with first-order transitions between these phases. The non-monotonic dependence of the field-induced birefringence can be explained by the existence of a remanent magnetic moment of the nanorods and the negative anisotropy of their magnetic susceptibility. Therefore, the nanorods align parallel to a weak field but realign perpendicular to the field beyond Bc approximately 375 mT. In addition, other interesting phenomena appear upon application of a magnetic field: the disordered (i.e. isotropic in zero-field) phase becomes highly anisotropic and difficult to distinguish from the nematic phase. Both phases then acquire not only quadrupolar order but also dipolar order. The rectangular columnar phase is strongly stabilised versus the nematic one. Our experimental observations raise new theoretical questions about the phase diagram of these suspensions with respect to volume fraction and magnetic field intensity.

Journal Article↗
PubMed2007

Optimization of transfection mediated by calcium phosphate for plasmid rAAV-LacZ (recombinant adeno-associated virus-beta-galactosidase reporter gene) production in suspension-cultured HEK-293 (human embryonic kidney 293) cells.

rAAV (recombinant adeno-associated virus) has become a very useful gene-delivery vector for gene therapy. However, it is very difficult to generate rAAV using triple transfection on a commercial scale, owing to its low productivity and inconveniently adhesive nature of its culture. An optimal suspension-culture transfection procedure was developed for rAAV-LacZ production in suspended HEK-293 cells mediated by calcium phosphate (lacZ, a reporter gene, codes for beta-galactosidase). The study showed that cytotoxicity of transfection complexes and cell aggregation in suspension culture were two key factors affecting high suspension-culture transfection efficiency. Cytotoxicity of transfection complexes was influenced effectively by mixture of Ca(2+) and plasmid DNA when their concentrations were decreased from 300 to 150 mM and from 3.0 to 1.5 microg/ml respectively, as manifested by a relatively higher cell viability after suspension-culture transfection. Moreover, the transfection efficiency was still less than 15%. In addition, we explored the disruption of cell aggregation and the control of transfection-complex size with 2.0 mM EGTA treatment for 30 min before transfection and the addition of 100 mM Mg(2+) during transfection respectively, procedures which enhanced transfection efficiency significantly, owing to more contact and endocytosis between cells and transfection complexes. Finally, the high transfection level and rAAV-LacZ titre achieved under optimized suspension-culture transfection conditions, namely 40% and 5 x 10(11) v.g. (vector genomes)/60 ml of medium respectively, is promising for the technique's application in the large-scale production of rAAV.

Adenoviridae↗
PubMed1966

The uptake of homologous ribonucleic acid by rat-liver parenchymal cells in suspension.

1. Native or partially degraded RNA derived from intact rat liver, or from the parenchymal-cell or the non-parenchymatous fraction of liver, has been shown to be transported into rat parenchymal cells in suspension, without prior degradation to acid-soluble components, when the cell suspension is incubated with the RNA at 37 degrees . The amount of RNA of exogenous origin present in the parenchymal cells in an acid-precipitable form increased rapidly up to 30-60min., after which it gradually decreased, indicating intracellular degradation to acid-soluble components of the RNA taken up by the cells. 2. The RNA taken up by the parenchymal cells from the medium, and the acid-soluble products of its degradation within the cells, could be released back into the medium. 3. The RNA of exogenous origin present in acid-precipitable form in the parenchymal cells represented up to 5% of the RNA of the cells after 60min. of incubation. 4. When the concentration of RNA in the medium was less than 200mug./ml., over 10% of the RNA was transported in an acid-precipitable form in 60min. into the parenchymal cells incubated at a concentration of 2.3x10(6)/ml. 5. Ribonuclease inhibited the uptake of exogenous RNA by the parenchymal cells, whereas 2,4-dinitrophenol, sodium azide, protamine sulphate and polyvinyl sulphate had no significant effect. 6. The uptake of exogenous RNA by liver slices proceeded at a rate which was 4-20% of that obtained in the parenchymal-cell suspensions; the RNA taken up did not appear to become degraded, unlike that taken up by the cell suspensions. 7. It is concluded that dispersion of liver tissue to a suspension of single cells increases the permeability of the parenchymal cells to macromolecular RNA and creates conditions that lead to a rapid degradation of the RNA taken up.

Animals↗
PubMed1968

The effect of actinomycin D on the synthesis of ribonucleic acid and protein in rat liver parenchymal cells in suspension and liver slices.

1. Rat liver parenchymal cells in suspension are shown to require a higher concentration of actinomycin D than liver slices for equivalent inhibition of the incorporation of [(14)C]adenine, [(14)C]uracil and [(32)P]phosphate into RNA, and of (14)C-labelled amino acids into protein; protein synthesis is much less susceptible to actinomycin D inhibition than RNA synthesis in both the tissue preparations. Possible causes for these differences are discussed. 2. The uptake of [(3)H]actinomycin D in the first few minutes was much greater in the cell suspensions than in the tissue slices; that in the next 1-4hr. was about the same in both the cases. The uptake by both the tissue preparations was at all times proportional to the concentration of the drug within the range 0.5-2.0mug./ml. 3. In the slices actinomycin D taken up initially was concentrated almost exclusively in the nuclei; with time the concentration of the drug in the mitochondria and the supernatant increased more rapidly than in the nuclei though at no stage did it exceed that in the nuclei. In the cell suspension the largest concentration of the drug taken up initially was found in the supernatant; most of the drug taken up subsequently also stayed in the supernatant. 4. When the drug concentration in the incubation medium was 1mug./ml., its concentration within the parenchymal cells in suspension and the parenchymal cells in the slices reached 2.2 and 1.6mug./cm.(3) of cellular volume respectively. On average, 7% of the drug was removed from the medium by the cells in suspension and 23% by the cells in the slices; the average ratio of intracellular to extracellular concentration was 2.4 in the former and 2.1 in the latter case.

Adenine↗
PubMed1998

Hindlimb suspension induces the expression of multiple myosin heavy chain isoforms in single fibres of the rat soleus muscle.

To examine the expression patterns of myosin heavy chain (MHC) isoforms in single fibres of the soleus muscle following weightlessness, 10-week-old male Wistar rats were subjected to hindlimb suspension for 4 weeks. Hindlimb suspension resulted in reduced body weight and absolute and relative mass of the soleus muscle compared with controls (P < 0.01). A total of 975, 892 and 1098 single fibres from pre-suspended controls, age-matched controls and suspension groups, respectively, were subjected to MHC analyses using SDS-PAGE. Single fibres containing only MHC I decreased (87.9 vs. 67.9%, P < 0.05) and single fibres containing only MHC IIa disappeared after hindlimb suspension. On the contrary, single fibres containing multiple type II MHC isoforms were observed as follows: 10.1% single fibres contained MHCs IIa and IId; 14.1% contained MHCs I, IIa and IId; and some (1.4%) expressed the MHC IIb isoform with MHCs IIa and IId. The relative content (%) of each MHC isoform in MHC hybrid single fibres was calculated using densitometer scanning. The MHCs IIa and IId hybrid single fibres contained the same amount of MHC IIa (51.3 +/- 6.3%) and MHC IId (48.7 +/- 6.3%). In the MHCs I, IIa and IId hybrid single fibres, the percentage of MHC IIa was distributed in a wide range (approximately 80%), whereas the percentage of MHC IId was a relatively low range (approximately 40%), and the relative content of MHC I was inversely correlated with that of MHC IIa and MHC IId, respectively. The fibre type composition of suspended soleus muscle, analysed by histochemical myosin ATPase staining, was changed, with a decrease in the percentage of type I fibres and an increase in that of type IIA fibres. Our results indicate that hindlimb suspension induces multiple type II MHC expression in the soleus single fibres and suggest that the single fibres containing multiple type II MHC isoforms should be classified into type IIA.

Adenosine Triphosphatases↗
PubMed1998

Does bone anchor fixation improve the outcome of percutaneous bladder neck suspension in female stress urinary incontinence?

OBJECTIVE: To evaluate the outcome of a new modification of percutaneous needle suspension, using a bone anchor system for fixing the suture at the public bone, and to compare the results with those published previously. PATIENTS AND METHODS: From March 1996, 37 patients with stress urinary incontinence (> 2 years) were treated using a bone anchor system. On each side the suture was attached to the pubocervical fascia and the vaginal wall via a broad 'Z'-stitch. A urodynamic investigation performed preoperatively in all patients confirmed stress incontinence and excluded detrusor instability. The outcome was assessed by either by a clinical follow-up investigation or using a standardized questionnaire, over a mean follow-up of 11 months (range 6-18). RESULTS: In the 37 patients, the procedure was successful in 25 (68%), with 16 (43%) of the patients completely dry and nine (24%) significantly improved. Removal of the bone anchor and suture was necessary in two patients, because of unilateral bacterial infection in one and a bilateral soft tissue granuloma in the other. One bone anchor became dislocated in a third patient. In two cases where the treatment failed, new detrusor instability was documented urodynamically. Minor complications were prolonged wound pain in 10 (26%) and transient urinary retention or residual urine in 12 patients (32%). CONCLUSION: The poor success rate in the study corresponds with the long-term results of conventional or modified needle suspension procedures and does not reinforce the optimistic results of bone anchoring published recently. Because of the poorer long-term results from percutaneous needle suspension than from other techniques of open retropubic bladder neck suspension, it remains questionable whether percutaneous needle suspension should be considered a first-line procedure for the treatment of female stress urinary incontinence.

Adult↗
PubMed1998

A questionnaire-based outcome analysis of the Stamey bladder neck suspension procedure for the treatment of urinary stress incontinence: the Hannover experience.

OBJECTIVES: To evaluate the long-term continence rate, including subjective satisfaction and therapy-associated morbidity, of patients undergoing Stamey bladder neck suspension. PATIENTS AND METHODS: Eighty-five women (median age 55 years, range 30-85) with urinary stress incontinence treated by Stamey bladder neck suspension at our institution between 1987 and 1995 were evaluated using an anonymous questionnaire over a mean (range) follow-up of 61 (13-93) months. RESULTS: Of the 85 patients, 44 (52%) reported an improvement in clinical symptoms at the evaluation and 29 (34%) were completely continent after the Stamey procedure. However, 53 (62%) patients reported subjective satisfaction with the result, because they had a durable improvement in continence for a mean (range) of 44 (10-79) months. There was no correlation between the number of previous urogynaecological operations undergone by the patients and the success of the Stamey procedure. However, the frequency of complications other than urinary retention was significant during and after surgery, at 27%, and in accord with the complication rate reported in earlier studies. CONCLUSIONS: Compared with other bladder neck suspension procedures, e.g. Burch colposuspension, the Stamey procedure appears to be associated with a higher frequency of postoperative recurrent urinary stress incontinence. Therefore, the Stamey procedure should only be used if the patient demands a minimally invasive surgical procedure for bladder neck suspension. Although approximately equal to 60% of patients were satisfied with the durable improvement in clinical symptoms, it is appropriate to inform patients before surgery of the high recurrence rate after Stamey bladder neck suspension.

Adult↗
PubMedDate not supplied

Inactivation of viruses in platelet suspensions that retain their in vitro characteristics: comparison of psoralen-ultraviolet A and merocyanine 540-visible light methods.

The ability of two fundamentally different photochemical procedures to inactivate model viruses in platelet suspensions was compared. Merocyanine 540 (MC 540) with visible light was used as an example of an oxygen-dependent chemical-directed at the viral membrane, and aminomethyl trimethyl psoralen (AMT) with ultraviolet A light (UVA) was used as an example of a nucleic acid-directed system. Antiviral conditions in petri dishes were identified and the effects of these procedures on platelet suspensions in plastic storage containers were studied. Concentrations of photochemicals in the 10 to 150 mumol range with 30 to 60 minutes of visible light (MC 540) or 1 to 2 minutes of UVA (AMT) readily inactivated 5 to 6 log10 of vesicular stomatitis virus (VSV) and other model viruses in platelet suspensions, provided the plasma concentration was reduced to about 15 percent by the use of a synthetic platelet storage medium. Extracellular pH, morphology scores, and aggregation response dropped markedly when platelets were treated with MC 540 and visible light. However, treatment with 136 mumol per L of AMT and 1 to 3 minutes of UVA could inactivate 5 log10 of VSV in platelet suspensions with retention of platelet characteristics for 4 days, particularly if oxygen levels were reduced during treatment. These studies demonstrate that AMT-UVA treatment meets the initial requirements for virus inactivation in platelet suspensions.

Blood Platelets↗
PubMed1997

The effects of mountain bike suspension systems on energy expenditure, physical exertion, and time trial performance during mountain bicycling.

The purpose of this 3-Phase study was to investigate the effects of suspension systems on muscular stress, energy expenditure, and time trial performance during mountain biking. Three suspension systems were tested, a rigid frame bike (RIG), a suspension fork bike (FS), and a front and rear suspension bike (FSR). Phase I and II consisted of cycling at 16.1 km.hr-1 over a flat, bumpy course for 63 min. Phase III consisted of ascending (ATT), descending (DTT), and cross country (XTT) time trials. Phase I assessed muscular stress by 24 h change in CK, Phase II assessed HR, VO2, VE, and Phase III assessed performance responses to the suspension systems. The 24 hr change in CK was greater for RIG than FS and FSR (+91.9 +/- 79.5 IU vs +8.6 +/- 17.5 IU and +9.7 +/- 21.8 IU). Mean HR was greater for RIG than FS and FSR (153.7 +/- 15.6 bpm vs 146.7 +/- 15.4 bpm, 146.3 +/- 16.2 bpm). Subjects rode significantly faster on FS than FSR and RIG during the XTT (30.9 +/- 2.0 min vs 32.3 +/- 3.6 min, 32.3 +/- 3.2 min). Subjects RPE was lower for FSR than FS and RIG, however, no differences were observed for VO2, VE, ATT, or DTT. Cyclists incurred less muscular stress, indicated by CK and HR, when riding the FS and FSR. Although the FS and FSR weigh from 0.7 to 2.2 kg more than RIG, no differences were observed for energy expenditure and that riding the FS in a XTT resulted in a faster finishing time than FSR or RIG.

Adult↗
PubMed2001

Inhalation delivery of proteins from ethanol suspensions.

To circumvent inherent problems associated with pulmonary administration of aqueous-solution and dry-powder protein drugs, inhalation delivery of proteins from their suspensions in absolute ethanol was explored both in vitro and in vivo. Protein suspensions in ethanol of up to 9% (wt/vol) were readily aerosolized with a commercial compressor nebulizer. Experiments with enzymic proteins revealed that nebulization caused no detectable loss of catalytic activity; furthermore, enzyme suspensions in anhydrous ethanol retained their full catalytic activity for at least 3 weeks at room temperature. With the use of Zn(2+)-insulin, conditions were elaborated that produced submicron protein particles in ethanol suspensions. The latter (insulin/EtOH) afforded respirable-size aerosol particles after nebulization. A 40-min exposure of laboratory rats to 10 mg/ml insulin/EtOH aerosols resulted in a 2-fold drop in the blood glucose level and a marked rise in the serum insulin level. The bioavailability based on estimated deposited lung dose of insulin delivered by inhalation of ethanol suspension aerosols was 33% (relative to an equivalent s.c. injection), i.e., comparable to those observed in rats after inhalation administration of dry powder and aqueous solutions of insulin. Inhalation of ethanol in a relevant amount/time frame resulted in no detectable acute toxic effects on rat lungs or airways, as reflected by the absence of statistically significant inflammatory or allergic responses, damage to the alveolar/capillary barrier, and lysed and/or damaged cells.

Administration, Inhalation↗
PubMed1988

Cell adhesion induces expression of growth-associated genes in suspension-arrested fibroblasts.

A methylcellulose suspension system that prevents cell-surface contact with the substrate was used to study the role of cell adhesion in the regulation of proliferation. The nonadhesive conditions established by suspension culture cause BALB/c 3T3 (A31) cells to enter a G0 state of growth arrest within 48 hr as defined by an inhibition of DNA synthesis and a suppression of c-myc and histone mRNA expression. The adhesion of these suspension-arrested cells rapidly induces c-fos, c-myc, and actin gene expression. This stimulation did not depend on the presence of serum since the adhesion of suspension-arrested cells, in the absence of serum, also induced the expression of c-fos and c-myc mRNAs. In addition, adhesion onto fibronectin increased the number of cells able to respond to epidermal growth factor and insulin and progress into S phase. These results indicate that adhesion of suspension-arrested cells activates the G0/G1 transition independent of growth factors.

Actins↗
PubMed2003

Determination of phenolic antioxidant compounds produced by calli and cell suspensions of sage (Salvia officinalis L.).

Sage (Salvia officinalis L.) calli were established by culturing internodal segments, excised from aseptic seedlings, on MS basal medium gellied with agar and supplemented with 0.05 mg/L dichlorophenoxyacetic acid (2,4-D) in presence of benzyladenine (BA) or zeatin (ZEA) or kinetin (KIN), at 1.5 mg/L. Suspended cells were established by transferring one callus to 50 mL of liquid MS basal medium devoid of agar and containing the same type of hormonal supplementation used in respective calli growth. The highest growth of calli and suspensions occurred with 1.5 mg/L ZEA. However, with this cytokinin supplementation, as well as with 1.5 mg/L KIN, both in presence of 0.05 mg/L 2,4-D, suspensions differentiated small root shaped structures. Well shaped, majority single cell suspensions were formed under the effect of 0.05 mg/L 2,4-D and 0.5 mg/L KIN. Calli grown with 0.05 mg/L 2,4-D and 1.5 mg/L BA and suspended cells grown with 0.05 mg/L 2,4-D and ZEA or KIN at 1.5 mg/L, or KIN at 0.5 mg/L, were searched for phenolics production. Twelve phenolic compounds were identified in calli: gallic acid, 3-O-caffeoylquinic acid, 5-O-caffeoylquinic acid, caffeic acid, rosmarinic acid, hesperetin, epirosmanol, hispidulin, genkwanin, carnosol, carnosic acid, and methyl carnosate. With the exception for genkwanin and epirosmanol all of these phenolic compounds were also produced by the sage suspension cultures grown in the presence of 1.5 or 0.5 mg/L KIN. Genkwanin was the only phenolic absent in the suspensions grown with 1.5 ZEA. Suspended cells, grown with 0.5 mg/L KIN, and calli cultures showed the highest specific accumulation of the total phenolics, with rosmarinic acid representing 94-97%.

Antioxidants↗
PubMed1991

Production of Ah receptor ligands in rat fecal suspensions containing tryptophan or indole-3-carbinol.

An assay system was developed to test whether bacteria in the gastrointestinal tract are capable of metabolizing tryptophan to compounds that are able to bind to the aryl hydrocarbon (Ah) receptor. Tryptophan (1 mM) was added to feces diluted 1:1,000 in phosphate-buffered saline and incubated at 37 degrees C overnight. The suspensions were extracted with chloroform to obtain the hydrophobic compounds. To test for the presence of Ah receptor ligands, a competition binding assay using [2-125I]iodo-7, 8-dibromodibenzo-p-dioxin and Hepa 1c1c7 cytosol was employed; it was capable of detecting picogram levels of a competing ligand with similar affinity. Fecal suspensions in the presence of 1 mM tryptophan and oxygen are capable of producing greater than 60% inhibition of radioligand binding per 10 micrograms of feces. In contrast, oxygen-equilibrated fecal suspensions without tryptophan and argon-equilibrated fecal suspensions with tryptophan exhibited 10% inhibition of radioligand binding per 10 micrograms of feces in the competition binding assay. Other indolylic compounds and amino acids were similarly tested. Histidine, tyrosine, phenylalanine, glycine, indole-3-acetic acid, and tryptamine were all negative in this assay. Indole-3-carbinol was capable of forming compounds that bind to the Ah receptor under a variety of conditions: in fecal suspensions with or without oxygen, in 50 mM HCl for 80 minutes, and in neutral pH buffer overnight at 37 degrees C. Addition of oxygenated tryptophan-fecal incubation extracts to Hepa 1 and Hepa c4 mutant (defective Ah receptor) cell cultures resulted in the induction of ethoxyresorufin O-deethylase activity in Hepa 1 cells, but no induction was observed in Hepa c4 cells. These results suggest that bacteria in the gastrointestinal tract under the proper conditions are able to metabolize tryptophan to compounds that are Ah receptor ligands.

Animals↗
PubMed1998

Microbial degradation of carbosulfan by carbosulfan--and carbofuran-retreated rice soil suspension.

The role of microorganisms in the degradation of carbosulfan (2,3-dihydro-2,2-dimethyl-7-benzofuranyl-(di-n-butyl)-aminosulfenyl++ + methyl carbamate), an analogue of carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl-N-methyl carbamate) was studied by selective enrichment of microorganisms degrading either or both insecticides by repeated application of the insecticides, individually or in combination to flooded soil. Soil suspension from the pots treated with carbosulfan and carbofuran, individually or in combination collected after two applications, effected distinctly more rapid hydrolysis of carbosulfan than did the suspension from untreated pots or the uninoculated medium. The rate of hydrolysis was further accelerated by soil suspensions collected after six applications of the insecticides in the order carbosulfan treated > carbofuran treated > carbosulfan + carbofuran treated. The ability of treated and untreated suspension to degrade carbofuran was also studied. The rate of degradation of carbofuran by the suspension was in the order carbofuran retreated > carbosulfan + carbofuran retreated > carbosulfan retreated soil. Further involvement of microorganism in the rapid degradation of carbosulfan was confirmed by testing the degradation in sterilized and nonsterilized enrichment culture.

Bacteria↗
PubMed2002

Evaluating the dissolution behavior of zinc-complexed protein suspensions by computer modeling and simulation.

In vitro dissolution of zinc insulin suspensions can be promoted by the complexation of zinc with an ionic species for which the zinc ion has a greater affinity. Studies conducted by our group have previously shown that the rate-limiting steps that govern the dissolution of zinc-complexed insulin suspension may be (1) chemical complexation (surface reaction) and (2) subsequent drug mass transport (diffusion and solubility). The purpose of this work was to use a computer simulation model to predict the dissolution behavior of zinc-complexed insulin suspensions and determine the influence of the above rate-limiting steps on the overall process of dissolution. A quasi-steady-state model was chosen which included the effects of a shrinking particle radius, the drug's solubility, and a convective mass transfer term. Based on this model, the computer simulation program evaluated dissolution behaviors of various model drugs, including zinc insulin suspensions. The experimental data obtained from actual dissolution experiments were superimposed on computer-generated profiles that incorporated quantitative values to key terms, namely the alpha (diffusion resistance) and beta (surface reaction resistance) values. Results demonstrated that the computer simulations could be used to predict the dissolution behavior of zinc-complexed protein suspensions by manipulating the alpha and beta values. Overall, the computer simulations indicated the involvement of both the surface reaction and the diffusion rate-limiting steps in zinc insulin dissolution, which was consistent with the results obtained from actual experimental studies.

Computer Simulation↗
PubMed1983

Control of rat C6 glioma cell proliferation: uncoupling of the inhibitory effects of hydrocortisone hormone in suspension and monolayer cultures.

We undertook a comparative study of the effects of the hormone hydrocortisone (Hy) on C6 glioma cells grown in monolayer and in suspension in cultures. We found Hy reversibly renders C6 cells anchorage- and serum-dependent for their growth. In monolayer cultures, Hy was found to inhibit cell cycle traversing exclusively at G1 phase. In agarose suspension, Hy was found to block colony development. Hy-resistant variants were selected and isolated in agarose suspension. Examination of these variants showed that cells selected for Hy-resistance in suspension can be Hy sensitive when anchored to a solid substrate. We conclude that resistance to Hy in suspension and resistance to it in monolayer culture are two independent phenotypes.

Animals↗
PubMed1987

Cell suspensions from porcine olfactory mucosa. Changes in membrane potential and membrane fluidity in response to various odorants.

A suspension of olfactory epithelial cells was prepared from porcine olfactory mucosa and the physiological functions of the suspension were examined. The membrane potential of the cell suspension, which was monitored by measuring the fluorescence changes of rhodamine 6G, was depolarized by an increase in the K+ concentration in the external medium. Various odorants depolarized the cell suspension in a dose-dependent fashion. The magnitude of depolarization by odorants was either unchanged or slightly increased by a reduction of the concentration of Na+, Ca2+, and Cl- in the external medium, which suggests that changes in the permeabilities of specific ions are not involved in depolarization by odorants. The application of various odorants to the cell suspension induced changes in the membrane fluidity at different sites of the membrane that were monitored with various fluorescent dyes [8-anilino-1-naphthalene sulfonate, n-(9-anthroyloxy) stearic acids, 12-(9-anthroyloxy) oleic acid, and (1,6-diphenyl-1,3,5-hexatriene)], which suggests that the odorants having different odors are adsorbed on different sites in the membrane. On the basis of these results, a possible mechanism of odor discrimination is discussed.

Animals↗