Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CULTURE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
PubMed2006

An optimal culture condition maintains human hepatocyte phenotype after long-term culture.

BACKGROUND: Long-term culture of primary hepatocytes from various species is impeded by a decrease of cell viability and a loss of hepatocyte-specific function. The aim of the present study was to investigate whether our optimal culture condition (OC) can maintain the phenotype of primary hepatocytes in long-term culture. METHODS: Primary human hepatocytes were cultured in either hepatocyte maintenance medium (HM) or OC for 2-4 weeks. Expression of hepatocyte-specific genes was determined by real-time quantitative RT-PCR. RESULTS: The level of albumin mRNA in human hepatocytes cultured in OC was 11-fold more than in HM and gene expression levels of alpha1-antitrypsin and transferrin were at approximately 40 and 11% of freshly isolated primary human hepatocytes. Electron microscopy revealed that cells in OC displayed hepatocyte properties (e.g. polarity, junctional complexes, bile canaliculi and glycogen particles). Cytochrome P4501A1/2 activity of hepatocytes cultured in OC was 15- and 17-fold higher than in HM at 2 and 4 weeks of culture, and DNA synthesis was higher. CONCLUSIONS: Using our optimal culture condition, we were able to maintain the phenotype of primary human hepatocytes in long-term culture. They not only maintain better liver-specific function, but also retain higher proliferative potential.

Journal Article↗
PubMed2003

Identification, isolation and quantification of representative bacteria from fermented cassava dough using an integrated approach of culture-dependent and culture-independent methods.

The use of denaturing gradient gel electrophoresis (DGGE) and traditional culture-depending methods for examining the bacterial community of traditional cassava starch fermentation were investigated. It appeared that DGGE profiles of total DNA of cassava dough exhibited 10 distinguishable bands. In contrast, DGGE fingerprints of bacteria recovered from enrichment cultures of fermented dough gave variable profiles containing fewer bands. Bands corresponding to five bacterial species detected by direct PCR-DGGE of total DNA from of cassava dough were also observed in DGGE patterns of enrichment cultures. Eighteen strains were isolated from cultures selected on the basis of their DGGE banding patterns. Assessment of bacterial identification by 16S rDNA sequence similarity revealed that band comigration implied sequence identity. Comparison of 16S rDNA sequences of excised DGGE bands and recovered pure culture isolates with those in GENBANK and the RDP databases revealed that representative bacteria of fermented cassava dough were Lactobacillus and Pediococcus species as well as species of Clostridium, Propionibacterium and Bacillus. Some Lactobacillus species detected in dough samples by sequence analysis of DGGE bands were not recovered in any of the five culture media and conditions used. On the other hand, some species recovered as pure cultures from enrichments were not detected by direct DGGE analysis of total bacterial DNA from cassava dough. Our results provide evidence of the necessity to combine both culture-dependent and culture-independent methods for better description of microbial communities in indigenous cassava starch fermentations.

Bacteria↗
PubMed1986

Sore throat: to culture or not to culture.

The traditional use of the throat culture to guide treatment of potential streptococcal pharyngitis recently has been questioned because of the following facts: antibiotic therapy within the first 48 hours of illness reduces the severity and symptoms of streptococcal pharyngitis; more rapid treatment of streptococcal pharyngitis may be more effective in prevention of rheumatic fever; clinical and Gram stain criteria can identify individuals with a high probability of a positive throat culture; new latex agglutination tests can identify within minutes individuals with a high probability of a positive throat culture; the throat culture may be falsely negative in individuals with partially treated pharyngitis, an inadequately swabbed or plated specimen, or an improperly read culture plate; and incomplete patient followup increases the true societal cost of traditional therapy based on throat culture results. These issues suggest that a sufficiently accurate screening test for guiding antibiotic therapy at the initial visit may be more clinically beneficial and cost effective than recalling all positive throat culture patients for antibiotic therapy. Nonetheless, a throat culture remains important when a screening test of a patient with suspected streptococcal pharyngitis is negative. Indications for culturing pharyngitis for other potential pathogens also are discussed.

Adult↗
PubMed2000

Comparison of nasal swab culture, quantitative culture of nasal mucosal tissue and PCR in detecting Streptococcus pneumoniae carriage in rats.

It is not known how well nasopharyngeal swab culture represents pneumococcal carriage status. We tested this by comparing swab culture to quantitative culture and quantitative PCR of mucosal tissue in a rat model of pneumococcal carriage. Quantitative culture and quantitative PCR identified significantly more carriers compared to swab culture (differences 15% and 33%, 95% CI 1-28% and 16-47%, p=0.04 and 0.001, respectively). The sensitivity and specificity of swab culture was 75/92% and 63/100% compared to quantitative tissue culture and quantitative PCR, respectively. The quantitative estimates of culture and PCR were very similar (Pearson correlation coefficient 0.79, p<0.001). In conclusion, even a well-controlled swab sampling markedly underestimates pneumococcal carriage rate, and simultaneous use of quantitative culture and PCR increases the number of positive samples by about one third.

Animals↗
PubMed2002

Maxillary sinus puncture and culture in the diagnosis of acute rhinosinusitis: the case for pursuing alternative culture methods.

OBJECTIVE: Traditional assessments of the microbial flora associated with acute bacterial rhinosinusitis have relied on maxillary sinus punctures (taps) and culture. These taps are now considered the gold standard for obtaining cultures and are used as the method of identifying bacterial pathogens in antimicrobial trials. Maxillary sinus taps are limited by discomfort to the patients and technical concerns. Because of these factors, the standard of performing taps has limited antibiotic trials and microbial surveillance. Alternatives to maxillary sinus taps have been explored. STUDY DESIGN: We conducted a retrospective, systematic review of the literature from 1950 to 2000 of articles comparing culture techniques in the nose and paranasal sinuses for acute bacterial rhinosinusitis. RESULTS: Nasal cultures have poor correlation to maxillary sinus cultures, whereas there is 60% to 85% concordance between endoscopically guided middle meatal cultures and maxillary sinus cultures. These studies, however, are all limited by small sample sizes and therefore are inadequate to make any concrete recommendations regarding the relative role of endoscopically guided middle meatal cultures as a formal method of pathogen identification in acute bacterial rhinosinusitis. CONCLUSION: A formal prospective study with sufficient sample size to assess the concordance between the microbial flora of the maxillary sinus punctures and middle meatal cultures in acute rhinosinusitis is recommended.

Acute Disease↗
PubMed2005

Culture of percutaneous bone biopsy specimens for diagnosis of diabetic foot osteomyelitis: concordance with ulcer swab cultures.

BACKGROUND: We assessed the diagnostic value of swab cultures by comparing them with corresponding cultures of percutaneous bone biopsy specimens for patients with diabetic foot osteomyelitis. METHODS: The medical charts of patients with foot osteomyelitis who underwent a surgical percutaneous bone biopsy between January 1996 and June 2004 in a single diabetic foot clinic were reviewed. Seventy-six patients with 81 episodes of foot osteomyelitis who had positive results of culture of bone biopsy specimens and who had received no antibiotic therapy for at least 4 weeks before biopsy constituted the study population. RESULTS: Pathogens isolated from bone samples were predominantly staphylococci (52%) and gram-negative bacilli (18.4%). The distributions of microorganisms in bone and swab cultures were similar, except for coagulase-negative staphylococci, which were more prevalent in bone samples (P < .001). The results for cultures of concomitant foot ulcer swabs were available for 69 of 76 patients. The results of bone and swab cultures were identical for 12 (17.4%) of 69 patients, and bone bacteria were isolated from the corresponding swab culture in 21 (30.4%) of 69 patients. The concordance between the results of cultures of swab and of bone biopsy specimens was 42.8% for Staphylococcus aureus, 28.5% for gram-negative bacilli, and 25.8% for streptococci. The overall concordance for all isolates was 22.5%. No adverse events--such as worsening peripheral vascular disease, fracture, or biopsy-induced bone infection--were observed, but 1 patient experienced an episode of acute Charcot osteoarthropathy 4 weeks after bone biopsy was performed. CONCLUSIONS: These results suggest that superficial swab cultures do not reliably identify bone bacteria. Percutaneous bone biopsy seems to be safe for patients with diabetic foot osteomyelitis.

Bacteria↗
PubMed1990

Evaluation of direct immunofluorescence, enzyme immunoassay, centrifugation culture, and conventional culture for the detection of respiratory syncytial virus.

Four methods of detecting respiratory syncytial virus (RSV) from clinical specimens were evaluated. A total of 410 specimens consisting of nasopharyngeal washes, aspirates, and swabs were simultaneously tested for the presence of RSV by direct immunofluorescence assay (DFA), enzyme immunoassay (EIA) (Kallestad Pathfinder), shell vial centrifugation culture (SVC), and conventional culture. DFA identified 146 (83%) of the 175 positive cases, EIA detected 153 (87%), SVC detected 127 (73%), and conventional culture detected 70 (40%). Conventional culture isolated an additional 19 respiratory viruses other than RSV. DFA and EIA were able to detect nonviable virus not isolated by a culture method, and SVC isolated low-titer virus not detected by conventional culture. DFA and EIA gave similar results; however, the EIA system was less dependent on technical expertise. The use of SVC enhanced the conventional culture system with 63 RSV isolates not recovered from the tube culture. We recommend complementary use of both culture and nonculture methods in the detection of RSV.

Antigens, Viral↗
PubMed1984

A new method for culture of larvae used in diagnosis of ruminant gastrointestinal strongylosis: comparison with fecal cultures.

A study was carried out in order to compare two techniques for culture of strongyle larvae: the usual fecal culture and a new one where eggs were extracted from feces and larvae were grown in a more defined medium (agar plate fortified with Earle's medium and yeast extract). The efficiency of "on-agar" cultures was better than that of the fecal cultures with a difference of 26% for Trichostrongylus colubriformis and 32% for Ostertagia circumcincta. The variability observed between the number of larvae collected from each culture was low (8% on average) in comparison with that of fecal cultures (15% on average) thus demonstrating a better reproducibility. On the other hand growth of the larvae was similar to that obtained in fecal medium. This new technique avoids the difficulty of controlling the conditions found in fecal cultures (particularly moisture) and could become a more accurate method for diagnosis than the conventional methods. A morphometric study of infective larvae derived from the two methods of culture was carried out. Despite the more defined conditions of development in the "on-agar" cultures, it was not possible to obtain sufficiently homogeneous populations with regard to their measurements so as to distinguish larvae merely with the help of these criteria.

Agar↗
PubMed1990

Ultrastructure of an identified molluscan neuron in organ culture and cell culture following axotomy.

We examined the ultrastructure of neuron 5 from the buccal ganglion of the mollusc Helisoma trivolvis after axotomy and organ culture, and after isolation of the same neuron in culture. Buccal ganglia containing axotomized neurons 5 were cultured either in host snails or in Leibovitz medium conditioned with ganglia. In addition, some neurons 5 were isolated from buccal ganglia by micro-dissection and plated into culture. Neuron 5 and its processes were identified in both whole mounts and plastic sections of buccal ganglia after intracellular injection with Lucifer Yellow or horseradish peroxidase. Five days after axotomy of neuron 5, thick sections of buccal ganglia stained with toluidine blue revealed that densely staining basophilic bodies (Nissl bodies) within the cytoplasm had dispersed, i.e., they had undergone chromatolysis. Coincident with chromatolysis was an overall increase in diffuse basophilic staining within the cytoplasm of neuron 5 when maintained in organ culture. The dispersion of Nissl bodies viewed by light microscopy correlated with a more freely arranged rough endoplasmic reticulum and associated polysomes within neuron 5 as seen by electron microscopy. Isolated neurons 5 did not possess densely staining Nissl bodies when examined after 2 days in vitro, thus indicating that chromatolysis occurred earlier in isolated neurons. Furthermore, no increase in diffuse cytoplasmic basophilia was observed within isolated neurons 5 cultured in vitro. However, isolated neurons 5 exhibited a marked increase in the number of lipid-like bodies (0.5-1.5 micron in diameter) that were particularly evident in scanning electron micrographs. Scanning and transmission electron micrographs revealed that the isolated neurons were free of associated glia, but non-neuronal cells (hemocytes) would attach themselves to the somata and neurites. Glia surrounding neuron 5 within buccal ganglia exhibited a marked hypertrophy following axotomy and organ culture. Hypertrophy of glia was absent, however, if ganglia were axotomized and left within the animal or axotomized ganglia were implanted into host animals and examined 5 days later by electron microscopy. These observations indicate that, following axotomy, a molluscan neuron may exhibit different morphological features depending on its microenvironment. In addition, the hypertrophy of glia surrounding neurons in Helisoma was not associated with axotomy per se, but with organ culture.

Animals↗
PubMed2007

Development and pattern of mRNA relative abundance of bovine embryos cultured in the isolated mouse oviduct in organ culture.

The aim of this study was to examine the development of bovine zygotes in isolated mouse oviducts (IMO) and the quality of the blastocysts produced. In vitro produced bovine zygotes were transferred into the ampullae of the IMO and cultured in SOF or KSOM. Control embryos were cultured in droplets of the same media. Following 6 days of culture, blastocysts were processed for nuclei counts or mRNA abundance. Culture in the IMO did not affect the proportion of zygotes developing to the blastocyst stage compared to the respective control droplets (SOF: 17.7 +/- 3.2% vs. 18.8 +/- 2.7%; KSOM: 20.7 +/- 2.6% vs. 22.2 +/- 2.8%). Culture in the IMO in KSOM resulted in an increased number of inner cell mass (ICM) nuclei; however, total nuclei number or incidence of apoptosis was unaffected. Culture in the IMO in SOF resulted in an increase (P < 0.05) in abundance of transcripts in blastocysts for Oct-4 and SOX, and reduced abundance of Glut-1, Na/K, Cx43, and survivin compared to blastocysts derived from culture in SOF alone. In contrast, culture in the IMO in KSOM resulted in increased abundance of transcripts for Glut-1, Cx43, Oct-4, and survivin and reduced expression of Na/K and SOX compared to KSOM alone. Transcripts for G6PDH, IFN-tau, and E-Cad were unaffected. These data confirm that the IMO is capable of supporting development of bovine embryos. Depending on the basal medium used, the pattern of transcript abundance in embryos derived from the IMO is similar to that of in vivo derived embryos.

Animals↗
PubMed1990

Assessment of hamster blastocysts derived from eight-cell embryos cultured in hamster embryo culture medium-2 (HECM-2): cell numbers and viability following embryo transfer.

The viability of hamster blastocysts, cultured from the eight-cell stage using hamster embryo culture medium-2, was examined by embryo transfer. Approximately 15-20 cultured hamster blastocysts were surgically transferred unilaterally to uterine horns of pseudopregnant recipient hamsters that had been mated to vasectomized males 3 days previously. Control recipients received in vivo developed, freshly recovered eight-cell embryos or blastocysts on day 2 or 3 of pseudopregnancy, respectively. Of the successful embryo transfers, the experimental group (receiving cultured blastocyts; n = 10) gave 51.8% implantations and 28.2% live pups. These values were closely similar to those of the controls; the percentages of control implantations and offspring were 51.1 and 34.0%, respectively, for eight-cell embryo transfer (n = 7, P greater than 0.69) and 48.5 and 28.9% for blastocyst transfer (n = 6, P greater than 0.52). To evaluate the quality of cultured hamster blastocysts, the following two parameters were examined. (1) The mean number of cells per blastocyst was 24.4 +/- 0.7 for cultured blastocysts. This value was similar to that (range, 14-24) obtained in this laboratory for in vivo developed freshly recovered blastocysts. (2) Oxygen consumption analysis revealed that cultured blastocysts actively respired at a level close to that observed with freshly recovered eight-cell embryos (slopes of oxygrams: 0.25 and 0.26, respectively). From these results, it is concluded that hamster blastocysts, cultured from the eight-cell stage, are (a) qualitatively similar to freshly recovered in vivo developed blastocysts and (b) biologically viable as revealed by the production of live offspring upon embryo transfer.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Cross-cultural variation in blood pressure: a quantitative analysis of the relationships of blood pressure to cultural characteristics, salt consumption and body weight.

This study has analyzed the relationships of cross-cultural variation in blood pressure to cultural characteristics, salt consumption and body weight. The data used were blood pressures for adults in 84 groups, ratings of cultural characteristics (based on anthropological data and made by raters who had no knowledge of the blood pressure data) and, where available, salt consumption and body mass index (weight/height2). Blood pressures were higher and the slopes of blood pressure with age were greater in groups which had greater involvement in a money economy, more economic competition, more contact with people of different culture or beliefs, and more unfulfilled aspirations for a return to traditional beliefs and values. Blood pressures were also higher in groups for which the predominant family type was a nuclear or father-absent family, as opposed to an extended family. For Negroes, groups who were descended from slaves had higher blood pressures than other groups. The correlations between blood pressures and involvement in a money economy were substantial and significant even after controlling for level of salt consumption and, for men, also after controlling for body mass index. For men there were also significant partial correlations between blood pressure and salt consumption, controlling for type of economy. For women there were significant partial correlations between blood pressure and body mass index, controlling for type of economy. In conclusion, cross-cultural variation in blood pressure appears to be due to multiple factors. One contributory factor appears to be psychosocial stress due to cultural disruption, including the disruption of cooperative relationships and traditional cultural patterns which frequently occurs during economic modernization. In addition, both the protective effects of very low salt consumption in some groups and differences in body weight appear to contribute to cross-cultural variation in blood pressure.

Adult↗
PubMed2004

A new culturing strategy optimises Drosophila primary cell cultures for structural and functional analyses.

Neurons in primary cell cultures provide important experimental possibilities complementing or substituting those in the nervous system. However, Drosophila primary cell cultures have unfortunate limitations: they lack either a range of naturally occurring cell types, or of mature physiological properties. Here, we demonstrate a strategy which supports both aspects integrated in one culture: Initial culturing in conventional serum-supplemented Schneider's medium (SM(20K)) guarantees acquisition of all properties known from 30 years of work on cell type-specific differentiation in this medium. Through subsequent shift to newly developed active Schneider's medium (SM(active)), neurons adopt additional mature properties like the ability to carry out plastic morphological changes, neurotransmitter expression and electrical activity. We introduce long-term FM-dye measurements as a tool for Drosophila primary cell cultures demonstrating the presence of increased, action potential-dependent synaptic activity in SM(active). This is confirmed by patch-clamp recordings, which in addition show that SM(active)-cultured neurons display different spiking patterns. Furthermore, we demonstrate that transmission can be evoked in SM(active) cultures, revealing the existence of synaptic plasticity. Thus, these culture conditions support developmental, structural and physiological properties known or expected from the nervous system, enhancing possibilities for future experiments complementing or substituting those in nervous systems of Drosophila.

Action Potentials↗
PubMed2006

Oxidative metabolism in cultured rat astroglia: effects of reducing the glucose concentration in the culture medium and of D-aspartate or potassium stimulation.

The glucose concentration in the culture medium may affect the energy metabolism of cultured cells. The oxidative metabolism of glucose in astrocytes might also be affected because the glucose concentration (25 mmol/L) of many culture media is higher than the physiological levels (approximately 3 mmol/L). In the present study, we assessed the effects of reducing the glucose concentration in the culture medium on the oxidative metabolism of glucose in cultured rat astroglia by measuring the oxidation rates of L-[U-14C]lactate or D-[U-14C]glucose to 14CO2. The effects of D-aspartate and elevated extracellular K+ levels on oxidative and glycolytic metabolism in astroglia were also investigated. The rates of [14C]lactate and [14C]glucose oxidation in astroglia cultured in a medium containing 2 mmol/L of glucose (astroglia2) were approximately twofold of those in astroglia cultured in a medium containing 22 mmol/L of glucose (astroglia22). D-Aspartate (500 micromol/L) significantly increased [14C]lactate oxidation by 156% in astroglia22 and by 83% in astroglia2. D-[U-14C]glucose oxidation in astroglia22 and astroglia2 was also increased by 94% and 76%, respectively. In contrast, an elevated extracellular K+ concentration (7.4 mmol/L) did not affect glucose and lactate oxidation, although it increased 2-deoxy-D-[1-14C]glucose phosphorylation. Astroglia grown in the physiological glucose concentration are more dependent on the oxidative metabolism of glucose than that in high-glucose concentration. Glucose concentration in culture medium has a strong influence on astrocytic oxidative capacity in vitro.

Animals↗
PubMed2006

Corneal epithelial cultures generated from organ-cultured limbal tissue: factors influencing epithelial cell growth.

PURPOSE: To explore the in vitro proliferative potential of human limbal epithelial cells after 31 degrees C organ-culture storage and to investigate putative factors influencing it. METHODS: 185 cultures of limbal explants were carried-out either from full-thickness explants (n = 102) or from enzymatically dissociated cells (n = 83) seeded on a feeder layer of human keratocytes. Epithelial outgrowth was assessed by phase contrast microscopy using a computerized image analysis software. Cell phenotype was evaluated by transmission electron microscopy and immunocytology. Univariate and multivariate analysis were performed to determine factors influencing epithelial growth in culture. RESULTS: An epithelial outgrowth of 100 square mm or more was observed in 52% of cultures, (average growth area: 440 +/- 256 mm at three weeks). Corneal epithelial phenotype was confirmed by transmission electron microscopy, and cytokeratin pattern. Cytokeratine 19, deltaNp63, nestin and vimentin positive staining revealed undifferentiated epithelial cells in both explant and cell suspension cultures at three weeks. Short death to cornea retrieval time (p < 0.03) and female donors (p < 0.01) were associated with higher cell growth. Enzymatic treatment of explants by trypsin, but not dispase, decreased cell proliferation at two (p < 0.03) and three weeks (p < 0.04). Donor age, duration of corneal storage, and source of the explant did not influence the cell growth. CONCLUSION: Organ-culture conditions can preserve limbal cell mitotic potential if limbal tissue is excised early after circulatory arrest. Human keratocytes can be used as a feeder layer allowing epithelial cells to maintain poorly differentiated phenotype in culture. Further investigations are needed to explain the influence of the donor sex on epithelial cell growth in culture.

Aged↗
PubMed1977

Tissue culture studies in Hodgkin's disease: Morphologic, cytogenetic, cell surface, and enzymatic properties of cultures derived from splenic tumors.

Monolayer and suspension cell cultures prepared from Hodgkin's disease tumors in the spleen were examined microscopically and by cytogenetics, tested for lymphocyte and monocyte cell surface properties, and assayed for enzymes by histochemical and spectrophotometric techniques. Hodgkin's disease monolayer cultures were composed of rapidly proliferating round and polygonal cells that were capable of propagation in vitro for an indefinite period of time. Abnormal aneuploid chromosomes were found in short-term Hodgkin's disease monolayers that had been passaged 16-20 times, and in established cell lines carried in culture longer than 3 yr and passaged more than 200 times. Cells fromHodgkin's disease monolayers contained lysozyme (muramidase), fluoride-resistant alpha naphthol acetate esterase, acid and alkaline phosphatase, and chymotrypsin-like activity. The monolayers did not exhibit specific cell surface markers or phagocytosis. Suspension cultures derived from Hodgkin's disease monolayers were composed of cells with aneuploid karyotypes and similar enzymes. The Hodgkin's disease suspension culture cells had surface receptors for complement and IgGFc, lacked surface or cytoplasmic immunoglobulin, and did not form Erosettes, react with an antithymocyte serum, nor exhibit phagocytosis. Normal monolayer culture cells, derived from adult spleen and human fetal spleen and thymus, were composed of spindle cells with a diploid number of chromosomes that could be carried for only a finite period of time in vitro. Normal cultured cells contained similar esterases and phosphatases, but were devoid of lysozyme and chymotrypsin-like activity. The morphologic, cytogenetic, cell surface, and enzymatic findings indicate that our Hodgkin's disease monolayer and suspension cultures are composed of cells with many properties suggesting an origin from monocytes (macrophages) rather than lymphocytes or fibroblasts. The presence of aneuploid karyotypes is consistent with a neoplastic origin and derivation from a malignant cell of Hodgkin's disease.

Alkaline Phosphatase↗
PubMed1982

Short-term primary culture of mouse interstitial cells: effects of culture conditions of androgen production.

This study examined the effects of culture conditions and hormone treatment on androgen production by mouse interstitial cells in short-term primary culture. Testicular interstitial cells (18-25% 3 beta-hydroxysteriod dehydrogenase-positive) were maintained in serum-free hormone supplemented medium. Basal (nonstimulated) androgen production was found to be plating-density dependent. Androgen production per cell increased dramatically in a time- and cell concentration-dependent manner. This effect was reproduced in low density cultures by addition of charcoal-stripped conditioned medium from high density cultures. The cell anchorage factors, fibronectin and poly-l-lysine, similarly enhanced basal androgen production but did not augment responsiveness to luteinizing hormone (LH). Coating of the culture surface with serum inhibited androgen production. Cultured cells remained responsive to LH for 4 to 5 days and both insulin (5 micrograms/ml) and epidermal growth factor (EGF) (3 ng/ml) augmented LH-stimulated androgen production. There was a transient increase in LH sensitivity and maximum LH-stimulated androgen production for 5 to 72 h in culture followed by a decline in androgen production to low levels after 4 to 5 days in culture. This loss of activity was partially prevented by addition of antioxidants to the medium or by reduction of the ambient O2 concentration to 1%.

Androgens↗
PubMedDate not supplied

Long-term culture of Xenopus presumptive ectoderm in a nutrient-supplemented culture medium.

Animal cap assay is a useful experimental model for investigating the activity of inducers in amphibian development. This assay has revealed that activin A is a potent mesoderm-inducing factor. However, it has been very difficult to induce highly differentiated tissues such as cartilage in a 3-4 day culture period. It was recently reported that jaw cartilage was induced in vitro in an animal cap that had been cultured for 14 days in Steinberg's solution using the sandwich culture method and activin A. Under these conditions, necrosis was occasionally observed in the explants. In this study, we have achieved long-term animal cap cultures in a nutrient-supplemented culture medium designated RDX. This medium was made by modifying the saline concentration of the RD medium previously developed as a basal medium for the serum-free culture of various kinds of mammalian cells. The explants cultured in RDX grew more vigorously compared with those in Steinberg's solution. RDX medium promoted a wider variety of tissue induction and gene expression in the animal caps than Steinberg's solution, and also increased the frequency of cartilage induction. Therefore, the supplemental nutrients may support and promote the differentiation of cartilage. This long-term culture method using RDX medium is useful for studying the differentiation of tissues or organs such as cartilage in vitro.

Animals↗