Hemagglutinating activity of Mycoplasma salivarium and its attachment to sheep red blood cells

Mycoplasma salivarium (ATCC 23064) and 10 other strains isolated from human saliva agglutinated red blood cells of rabbits and human types A and O weakly, and those of sheep (SRBC) and human type B strongly. Glycoproteins on the surface of the organism cells and N-acetylneuraminic acid residues and some sugars on SRBC were suggested to be involved in agglutination of SRBC. Protein A-like activity was detected in the organism cells. The organism cells were also shown to attach to SRBC in PPLO broth (Difco) supplemented with 10% horse serum, and bivalent metal ions were suggested to be involved in the attachment. The organism cells attaching to SRBC activated complement through the alternative pathway and lyzed the SRBC.     

New horizons in culture and valorization of red microalgae

Research on marine microalgae has been abundantly published and patented these last years leading to the production and/or the characterization of some biomolecules such as pigments, proteins, enzymes, biofuels, polyunsaturated fatty acids, enzymes and hydrocolloids. This literature focusing on metabolic pathways, structural characterization of biomolecules, taxonomy, optimization of culture conditions, biorefinery and downstream process is often optimistic considering the valorization of these biocompounds. However, the accumulation of knowledge associated with the development of processes and technologies for biomass production and its treatment has sometimes led to success in the commercial arena. In the history of the microalgae market, red marine microalgae are well positioned particularly for applications in the field of high value pigment and hydrocolloid productions. This review aims to establish the state of the art of the diversity of red marine microalgae, the advances in characterization of their metabolites and the developments of bioprocesses to produce this biomass.     

Bioluminescent high-throughput assay for the bacteria adherence to the tissue culture cells

The goal of this study was develop a rapid high-throughput method for the assessment of the bacterial adhesion to tissue culture cells and test this method by investigation of the adhesion and growth of pathogenic and non-pathogenic Escherichia coli strains in the presence of HeLa human epithelial cells. Fifteen strains of E. coli were transformed with a plasmid carrying the entire lux operon of Photorhabdus luminescens to make them bioluminescent. By using the Time-to-Detection approach and bioluminescence imaging in microplate format, the adherence and growth of bacteria in tissue culture medium in the presence of HeLa cells was monitored. It was observed that Eagle's minimal essential medium (EMEM) supplemented with 10% fetal bovine serum (FBS) significantly inhibited growth of E. coli. However, in the presence of HeLa cells the detected growth of E. coli was similar to the growth observed in LB medium. It was established that the initial number of E. coli cells present in the microplate directly correlated with the time necessary for the bioluminescence signal to reach the threshold level, hence allowing the accurate assessment of the adhered cells within 8-10 h. Neither bacterial adherence nor growth kinetics correlated with the pathogenicity of the strain though they were strain-specific. The developed approach provided new information on the interaction of E. coli with epithelial cells and could be used for both pathogenicity research and for the screening of potential therapeutic agents for the ability to minimize pathogen colonization of human tissues.     

Electric measurements can be used to monitor the attachment and spreading of cells in tissue culture.

A new electrical assay to measure the attachment and spreading of cells in tissue culture has been developed and substantiated by comparison with a more conventional assay. Small gold electrodes are vacuum deposited on the bottom of standard polystyrene culture dishes and coated with various proteins. As mammalian fibroblasts attach and spread on these surfaces, the measured impedance of the electrodes changes. These impedance changes reflect the amount of area blocked by the spreading cells. Since the weak electrical signals used have no noticeable effects on the cells, this is a very convenient method that is both quantitative and sensitive for measuring cell attachment and spreading.     

Characteristics of Helicobacter pylori attachment to human primary antral epithelial cells

Conventional cell lines are commonly used to study infection characteristics of the human gastric pathogen Helicobacter pylori. We sought to investigate bacterial attachment to human antral primary epithelial cells, a cell model that more closely resembles the human stomach than transformed cell lines. Primary cells were infected for 24 and 48 h with H. pylori. Morphological appearance of both the pathogen and the cells as well as features of colonization, attachment and internalization were evaluated by electron microscopy and compared to features observed with cultured AGS cells. H. pylori exhibited various shapes during colonization including the spiral, U-shaped, donut, and coccoid forms. The prevalence of each form seemed to be dependent on the infected donor tissue but, in general, changed with time to the coccoid form. Bacterial cell membranes progressively enlarged and appeared at times to be connected with microvilli. Bacterial attachment occurred to cells that were either unchanged, or had formed cup-like structures. Simultaneously, outer membrane vesicles were increasingly secreted from the bacteria, coinciding with increased cellular damage. We conclude that bacterial shape conversion, adherence and secretion of outer membrane vesicles are features of H. pylori infection. Primary gastric cell cultures closely imitate the antral environment and present an appropriate and useful model to study H. pylori pathogenesis.     

Altered ribonucleotide reductase activity in mammalian tissue culture cells resistant to hydroxyurea

Four Chinese hamster ovary cell lines and one mouse L cell line have been isolated which are resistant to the cytotoxic effects of hydroxyurea and guanazole. These five cell lines contain an altered ribonucleotide reductase activity as judged by a decreased sensitivity to the inhibitory action of both drugs. This is strong evidence that ribonucleotide reductase is one of the lethal sites of action for these two antitumour agents. The results are also consistent with the view that mammalian cell variants can arise from structural gene mutations.     

Nylon-fiber affinity selection of red blood cells and tissue culture cells on the basis of cell surface determinants

Nylon fibers coated with various lectins were used for the specific selection from mixed populations of erythrocytes or tissue culture cells with lectin receptors. Binding of human group O red blood cells to fibers treated with Ulex europaeus lectin I (H-specific) or of human group A red cells to fibers treated with Helix pomatia lectin (A-specific) was proportional to lectin concentration in the solution used to adsorb lectin to the fibers. Binding was blood group specific and increased with increasing concentrations of red cells applied to the fibers. Most adsorption of lectin to the fibers occurred within minutes; cell binding to lectin-coated fibers was almost complete within 30 min. Blood group negative Chinese hamster tissue culture cells bound non-specifically to Helix-coated fibers with a frequency of less than 10⁻⁴ input cells; the yield of viable, colony-forming cells bound to PHA-coated fibers was about 1%. Epithelial cells from cultures of amniotic fluid or fetal kidney contained 1–30% cells positive for the ABO blood group of the donor; blood group positive cells from these cultures were poorly bound to fibers coated with blood group specific lectins, though they bound readily to PHA-coated fibers, suggesting that presence of appropriate surface determinants may be necessary but not sufficient for lectin: cell binding in this system.     

Interaction of bacteria and red blood cells

The interaction of staphylococci, streptococci, meningococci, enterobacteria, leptospires and other microorganisms with red blood cells is considered. Three forms of the interaction of bacteria and red blood cells are discussed: adhesion, the influence of secretory factors on red blood cells, the action of pathogenic bacteria on hemoglobin. The applied aspects of the interaction of bacteria and red blood cells in the human body are presented in accordance with the results of clinical and laboratory studies.     

Production, characterization and antioxidant activity of exopolysaccharides from submerged culture of Morchella crassipes

The aim of this work was to investigate the fermentation optimization, molecular characterization, and antioxidant activity in vitro of exopolysaccharides (EPS) from Morchella crassipes in submerged culture. Firstly, an optimal medium for EPS production was obtained by single-factor experiment and central composite design as follows: maltose 44.79?g/L and tryptone 4.21?g/L. Then, one fraction of EPS was obtained from the culture filtrates by size exclusion chromatography and the molecular characteristics were examined by a multi-angle laser light scattering and refractive index detector system. The weight-average molar mass and the polydispersity ratio of the EPS fraction were revealed to be 1.961?×?10(4)?g/mol and 1.838, respectively. FT-IR spectroscopy was used for obtaining vibrational spectra of the purified EPS fraction. Finally, the antioxidant activity of EPS was investigated and the relationship with molecular properties was discussed as well.     

Estrogenic activity of phenol red in rat anterior pituitary cells in culture

The estrogenic activity of phenol red, a pH indicator widely used in cell culture media, was studied in rat anterior pituitary cells. After 72 hours of incubation with 40 microM phenol red, a 40-50% increase in prolactin cell content and a 100% stimulation of luteinizing hormone-releasing hormone induced luteinizing hormone release was observed. Both effects could be completely reversed by simultaneous incubation with the antiestrogen LY156758. In the rat uterine [3H] estradiol binding assay, phenol red showed a significant displacement at concentrations above 10 microM while its concentration in the commonly used culture media is about 40 microM. From the present results, we conclude that phenol red acts as a weak estrogen in normal tissues and that its estrogenic activity should be taken into account in studies using estrogen-sensitive cell or tissue cultures.     

Cell attachment to microcarriers affects growth, metabolic activity, and culture productivity in bioreactor culture

It is not well understood how changes from suspension to microcarrier cultures affect cell growth, metabolism, and yield of recombinant proteins. To investigate the effects of culture conditions on cell characteristics, fed-batch bioreactor cultures were performed under different culture conditions (suspension cultures, cultures attached to Cytodex 3 and Cytopore 1 microcarriers) using two different Chinese hamster ovary cell lines producing either secreted human placental alkaline phosphatase (TR2-255) or tissue plasminogen activator (CHO 1-15-500). In controlled, agitated bioreactors, suspension cultures reached cell densities and product titers higher than those in microcarrier cultures, in contrast to the results in static flask cultures. Growth and metabolic activities showed similar trends in suspension and microcarrier culture regardless of cell line. However, the responses of the specific productivities to the different culture conditions differed significantly between the cell lines.     

Immunological activity of lipopolysaccharide of Helicobacter pylori on human peripheral mononuclear blood cells in comparison to lipopolysaccharides of other intestinal bacteria

Abstract Lipopolysaccharide of Helicobacter pylori was tested for its mitogenicity and for its ability to stimulate cytokine release in human peripheral blood mononuclear cells (PBMC) of healthy and H. pylori -infected blood donors. Mitogenicity in PBMC induced by H. pylori LPS was similar to that induced by Campylobacter jejuni lipopolysaccharide, but lower than that induced by Escherichia coli lipopolysaccharide in the H. pylori negative blood donor group. Furthermore, H. pylori LPS was able to induce tumour necrosis factor (TNF) interleukin 1 (IL-1) and interleukin 6 (IL-6) secretion of PBMC. Compared with the ability of C. jejuni and E. coli lipopolysaccharides to stimulate cytokine release, H. pylori lipopolysaccharide induced a significantly lower TNF and IL-1 secretion of PBMC than the other tested bacterial lipopolysaccharides. Similar amounts of IL-6 release were obtained by stimulation of PBMC with H. pylori and C. jejuni lipopolysaccharides, whereas a higher IL-6 release was measured by stimulation with E. coli lipopolysaccharide. The results of this study suggest that H. pylori lipopolysaccharide has a lower immunological activity than lipopolysaccharides of other intestinal bacteria. This is probably due to its unusual acylation and phosphorylation pattern of lipid A.     

Adherence of intestinal and extraintestinalPseudomonas aeruginosa to tissue culture cells

The adherence pattern ofPseudomonas aeruginosa strains to HeLa, Vero and CHO cells was studied. The diffuse type of adherence was found to prevail on HeLa cells. It was characteristic for intestinal and environmental strains. Urinary strains revealed more often a localized adherence. A similar pattern was obtained with CHO cells. Experiments with Vero cells showed an equal distribution of intestinal strains regarding the diffuse, localized and mixed adherence. Urinary strains revealed mostly a localized adherence of a similar pattern as was observed on HeLa and CHO cells.     

Differential response of embryonic cells to culture on tissue matrices.

Cell responses to different natural substrates have been followed by scanning microscopy in order to evaluate the role of these substrates in morphogenesis. Matrix has been isolated then repopulated with suspensions of embryonic cells from chick skin, spinal ganglia, duodenal epithelium and heart. In some cases outgrowth from amphibian embryonic tissue was used. Basal lamina of the Xenopus tail may be exposed by freezing and thawing the tissue, or by EDTA treatment. The underlying lamella of orthogonally oriented collagen fibers may be exposed by use of trypsin or hyaluronidase. Trypsin causes more clumping of collagen fibers and a coarser texture of the matrix. On trypsin isolated basement lamella, nerve cell processes grow out on the surface and show no strong tendency to penetrate the lamella while skin mesenchymal cells commonly burrow among the collagen plies. Epithelial cells remain on the surface. On the basal lamina mesenchymal cells ruffle in early stages of culture, then flatten. Epithelial cells flatten rapidly on the lamina. These differences in cell response are in some cases closely related to cell behavior in vivo and suggest that cells show a selective response to the chemical composition of the substrate as well as to its physical conformation.     

Adhesion of lymphoid cells to fibroblasts in tissue culture

In this study we have examined the cellular and molecular specificity of lymphocyte interaction with fibroblasts. Using mitogen-activated T-cells, we found that attachment to fibroblasts was highly sensitive to protease treatment, and to an antibody raised against the purified lymphocyte plasma membrane, but it was not mediated by the MEL-14 surface antigen or phosphomannosyl receptors. Lymphocyte interaction with fibroblasts was also unaffected by monoclonal antibodies against the LFA-1, Mac-1, and Class II MHC antigen complexes. In contrast, adhesion of both T- and B-lymphocytes was strongly inhibited by fucoidan, a polymer of sulphated fucose, whereas fucose, mannan, and mannose 6-phosphate had no effect. Both B- and T-lymphoid cell lines were able to recognise and adhere to fibroblasts, although the marked differences between the attachment of the different types of cell did not appear to be related to their immunological function. The attachment of most of the cell lines was prevented by the presence of fucoidan, whereas the inhibition of binding of each of the lymphoid lines in the presence of the anti-T-lymphocyte plasma membrane antibody varied widely. These findings suggest that lymphocyte attachment to fibroblasts involves multiple cell surface receptors, and that these are expressed at different levels on specific T- and B-cells.