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At least 739 records · Page 41Linked to original sources
PubMed1995

Interleukin 13 suppresses cytokine production and stimulates the production of 15-HETE in PBMC. A comparison between IL-4 and IL-13.

We examined the ability of rIL-13 to regulate rIL-l alpha induced IL-1 beta, IL-1 receptor antagonist (IL-1ra) and IL-8 production in cultured peripheral blood mononuclear cells (PBMC), endothelial cells and fibroblasts. Furthermore we examined whether rIL-13 could influence the production of the arachidonic acid products LTB4, 12-HETE and 15-HETE by PBMC. rIL-1 alpha-stimulated PBMC cultures secreted high levels of IL-1 beta and IL-8; this could be inhibited to the level of unstimulated control cells by co-incubation with rIL-13 (10 ng/ml). IL-13 induced a 3-fold increase of the IL-1ra secretion which was inhibited by rIFN-gamma. In the presence of both rIL-1 alpha and rIL-13, endothelial cells increased IL-8 secretion, whereas dermal fibroblasts remained unchanged. Of the arachidonic acid metabolites examined, the greatest change was observed in the formation of 15-HETE. In unstimulated PBMC cultures the amount of 15-HETE was less than 4 ng/10(6) cells, whereas after addition of rIL-13 we measured a formation of 139 +/- 6.2 ng/10(6) cells. The effect of rIL-13 on the 15-HETE formation in PBMC was abolished by addition of 100 U/ml rIFN-gamma. rIL-13 only induced minor changes in the LTB4 and 12-HETE formation. Compared to IL-4, IL-13 induced a similar alteration of the cytokine cascade and arachidonic acid metabolism, supporting the hypothesis that the two cytokines use a common receptor complex or signal pathway.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1995

Adhesive substrates influence acid-productive activities of cultured rabbit osteoclasts: cultured osteoclasts with large vacuoles have enhanced acid-productive activities.

Since acid secretion of polarized osteoclasts on the bone surface has an important role in bone resorption, we examined the acid-productive activities of osteoclasts by measuring the pH of acidic organelles such as endosomes, lysosomes, and vacuoles in cultured rabbit osteoclasts with FITC-dextran as a fluorescent pH probe. The average pH value of acidic organelles of osteoclasts cultured on plain glass coverslips was 5.3 +/- 0.2. The pH of the acidic organelles correlated well with the size and amount of the vacuoles in the cells. Using this FITC-dextran method, we also examined the effects of adhesive substrates, such as type I collagen, vitronectin, and dentine, on the acid-productive activities of osteoclasts and found that the pH value of acidic organelles of osteoclasts cultured on dentine slices was significantly lower than that of osteoclasts cultured on plain glass coverslips. Likewise, in the case of the osteoclasts cultured on type I collagen- or vitronectin-coated glass coverslips, the pH values of acidic organelles were slightly lower and the proportion of osteoclasts having large vacuoles was increased compared with the cells cultured on the plain glass coverslips. These results indicate that osteoclasts containing large vacuoles have high acid-productive activities, and adhesive substrates such as type I collagen and vitronectin influence the formation of large vacuoles in cultured osteoclasts.

Acids↗
PubMed1996

Allergen dose dependent cytokine production regulates specific IgE and IgG antibody production.

The elicitation of a specific immune response against allergens depends on the recognition of antigenic determinants (epitopes) by specific T and B lymphocytes. In order to determine the relevant epitopes for human T and B cells and their features in the regulation and production of specific IgE and/or IgG antibodies, we have investigated the immune response to bee venom phospholipase A2 (PLA) in allergic and non-allergic subjects. This enzyme represents the major allergen in bee sting allergy. It consists of 134 amino acid residues with a carbohydrate side chain at position 13 and is available as recombinant protein. We have developed PLA-specific T-cell clones from bee sting allergic and non-allergic human subjects. Using a panel of dodecapeptides overlapping in 10 residues and a large set of 18-25 mer overlapping peptides, we detected three epitopes that were recognized by peripheral blood T-cells and T-cell clones. A fourth determinant involved the carbohydrate moiety on Asn13 of PLA. Whereas the CHO-depending epitope seems to be mostly active in allergics, the other three epitopes are equally recognized by peripheral blood mononuclear cells (PBMC) of both allergic and non-allergic individuals. In T-cell clones, the ratio of IL-4/IFN gamma cytokines and the quality of the activating signal depend on the strength of the binding of the MHC-II/Ag/TcR complex between APC and T-cells. The number of antigen-specific APC-T-cell contact sites can be varied in vitro by changing the dose of antigen added to the cell culture. While isotype switch for both IgE and IgG4 requires IL-4, this cytokine suppresses antigen-specific IgG4 production by already switched B-cells. Therefore, IL-4 and IFN gamma display counter-regulatory effects on the production of IgE being responsible for atopic states and IgG4 antibodies which are signs of a normal immune response to allergen and act as protective antibodies. The combination of this counter-regulation of IgE and IgG4 antibodies with the fundamental law of mass action for chemical equilibrium reactions revealed that the antigen concentration governs to a great part the ratio of IL-4/IFN gamma secretion and therefore the formation of IgE and IgG and allergy or protection, together with the equilibrium constant K, which represents immunological individuality and a measure of Ag presentation.

Allergens↗
PubMed1984

Defective interleukin-1 production by monocytes from patients with malignant disease. Interferon increases IL-1 production.

Interleukin-1 (IL-1) production by monocytes of patients with various forms of malignant disease was measured after activating the cells with either lipopolysaccharide or malignant K562 cells. Monocytes from all the patients with large tumour masses, including 10 patients with hepatocellular carcinoma, produced considerably less IL-1 than controls or patients with small tumour burdens. After treating control or patient monocytes with human leucocyte interferon for 1 h prior to activation, IL-1 production was markedly improved. Depressed IL-1 production is, therefore, a further aberration in mononuclear function observed in patients with cancer.

Adult↗
PubMed1987

Glycerol production in relation to the ATP pool and heat production rate of the yeasts Debaryomyces hansenii and Saccharomyces cerevisiae during salt stress.

Changes in glycerol production and two parameters related to energy metabolism i.e. the heat production rate and the ATP pool, were assayed during growth of Saccharomyces cerevisiae and Debaryomyces hansenii in 4 mM and 1.35 M NaCl media. For both of the yeasts, the specific ATP pool changed during the growth cycle and reached maximum values around 10 nmol per mg dry weight in both types of media. The levels of glycerol were markedly enhanced by high salinity. In the presence of 1.35 M NaCl, D. hansenii retained most of its glycerol produced intracellularly, while S. cerevisiae extruded most of the glycerol to the environment. The intracellular glycerol level of S. cerevisiae equalled or exceeded that of D. hansenii, however, with values never lower than 3 mumol per mg dry weight at all phases of growth. When D. hansenii was grown at this high salinity the intracellular level of glycerol was found to correlate with the specific heat production rate. No such correlation was found for S. cerevisiae. We concluded that during salt stress, D. hansenii possesses the capacity to regulate the metabolism of glycerol to optimize growth, while S. cerevisiae may not be able to regulate when exposed to different demands on the glycerol metabolism.

Adenosine Triphosphate↗
PubMed1986

Primary and secondary structural homologies between the HIS4 gene product of Saccharomyces cerevisiae and the hisIE and hisD gene products of Escherichia coli and Salmonella typhimurium.

A detailed comparative analysis of the Escherichia coli and Salmonella typhimurium hisIE and hisD gene products and the functionally equivalent, single, HIS4 gene product of Saccharomyces cerevisiae permitted several insights concerning the relationship between these genes. Our analysis supports the idea that HIS4 results from the fusion of his IE and hisD. The comparison permitted a more precise definition of the functional domains of hisI/HIS4A and hisE/HIS4B as well as the two functional domains of hisD/HIS4C. The homologies between the bacterial and yeast sequences suggest a region of the hisD/HIS4C protein that may constitute one of the active centres. A large fragment at the amino terminal region of the yeast protein is missing from the bacterial hisIE gene product and is probably not needed for catalytic activity. Another region of non-homology in the yeast protein is probably a peptide bridge connecting the HIS4AB domain to HIS4C. Although the overall homology at the level of amino acid sequence is modest (about 38%) there is a striking similarity when the hydropathic patterns and predicted secondary structural configurations of these proteins are compared.

Amino Acid Sequence↗
PubMed1977

[Metabolic products of microorganisms. 166. Optimization of the desferri-ferricrocin production by Aspergillus viridi-nutans Ducker & Thrower (author's transl)].

At low iron(III)-concentrations (less than 10(-5) M) the fungus Aspergillus viridi-nutans Ducker & Thrower excretes desferri-ferricrocin as the main sideramine into the culture medium. While this compound accounts for 95% of the sideramines produced, small amounts of additional sideramines may also be detected. In a search for an inexpensive nutrient medium for optimum production of desferri-ferricrocin, experiments using shake flasks with good aeration were undertaken initially. The best medium conditions were then employed in a fermentor system. In a 20-1 fermentor with "intensor" system, it was shown that at certain growth rates there was an inverse correlation between rate of growth and rate of sideramine production. A defined nutrient medium of glucose plus acetate as carbon sources, and urea or ammonium acetate as nitrogen sources was used. Two different feeding regimens were used in response to changes of pH or to changes of partial pressure of oxygen in the submerged culture: acetic acid/urea or acetic acid/ammonium acetate additions regulated these conditions. The rate of sideramine production under such feeding achieved a maximum of 20 mg 1(-1) h-1 over a period of several days.

Acetates↗
PubMed1986

Livestock production in central Mali: ownership, management and productivity of poultry in the traditional sector.

A survey of small-scale poultry production in an urban and two agropastoral systems covered 381 households. Less detailed information was also obtained from a small sample in a transhumant pastoral system. More households owned poultry in the rice (89.5%) than in the millet (81.1%) or urban (57.1%) systems. Domestic fowl were commonest in all systems followed by pigeons, Guinea fowl and then ducks, although the last were absent from the millet zone. Most families kept only one species but there was more diversification in the rice system. Flock sizes were largest in the rice system for fowls, Guinea fowl and pigeons while duck flocks averaged more birds in the urban area. Females predominated in all species except pigeons where sex ratios were about equal. Management practices in relation to housing, feeding, health care and consumption and marketing are described. Productivity figures relating to egg production, egg size, hatchability, growth and mortality are provided.

Animal Husbandry↗
PubMed2003

Sunscreen products increase virus production through prophage induction in marine bacterioplankton.

Classical pollutants (e.g., hydrocarbon, pesticides) have been recently recognized to induce lytic cycle in lysogenic bacteria, but information on micro-pollutants is almost completely lacking. We investigated the effects of cosmetic sun products (sunscreen and solar oil) on viral abundance and bacterial activity. We found that both sunscreen and solar oil acted as pollutants, inducing viral development and controlling bacterial abundance and production, thus leading to an increase of the virus to bacterium ratio. Short-term experiments revealed that sunscreen supplementation induced the lytic cycle in a large fraction of total bacterial abundance (13-24% of bacteria, at low and high concentrations, respectively), whereas solar oil had a lower impact (6-9%). A synchronized development of the phage-host system was observed only after sunscreen addition. The addition of sunscreen, even at low concentrations, had a significant impact on all enzymatic activities (aminopeptidase, glucosidase, and phosphatase), which increased significantly. However, when enzymatic activities were normalized per cell, a selective enhancement was observed for certain enzymes (e.g., aminopeptidase) and inhibition for others (e.g., glucosidase). These results indicate that sunscreen products can modify C, N, and P biogeochemical cycling in seawater and increase virus abundance through prophage induction in marine bacterioplankton.

Aminopeptidases↗
PubMed2002

Engineering an indene bioconversion process for the production of cis-aminoindanol: a model system for the production of chiral synthons.

Cis-aminoindanol, a key chiral precursor to the HIV protease inhibitor CRIXIVAN, can be derived from indene oxidation products of (2R) stereochemistry. A number of different microorganisms, notably strains of the genera Pseudomonas and Rhodococcus, have been isolated that catalyze the oxygenation of indene to indandiol with greater stereospecificity than is achievable through traditional chemical synthesis. The yield and ultimate optical purity of indandiol produced in such biocatalytic processes is influenced by the intrinsic stereospecificity of the oxygenase(s), enantioselective dehydrogenation, and the loss of substrate to alternate, undesirable metabolites. Metabolic engineering of any indene bioconversion system for the commercial-scale production of cis-aminoindanol must account for these influences, as well as pathway fluxes and enzyme regulation, to optimize the formation of oxygenated precursors with useful stereochemistry. As such, the process by which bacterial systems carry out the bioconversion of indene to indandiol serves as a model for biological production of industrially relevant chiral synthons.

Biotechnology↗
PubMed2005

Cell adaptation to solvent, substrate and product: a successful strategy to overcome product inhibition in a bioconversion system.

Carvone has previously been found to highly inhibit its own production at concentrations above 50 mM during conversion of a diastereomeric mixture of (-)-carveol by whole cells of Rhodococcus erythropolis. Adaptation of the cells to the presence of increasing concentrations of carveol and carvone in n-dodecane prior to biotransformation proved successful in overcoming carvone inhibition. By adapting R. erythropolis cells for 197 h, an 8.3-fold increase in carvone production rate compared to non-adapted cells was achieved in an air-driven column reactor. After an incubation period of 268 h, a final carvone concentration of 1.03 M could be attained, together with high productivity [0.19 mg carvone h(-1) (ml organic phase)(-1)] and high yield (0.96 g carvone g carveol(-1)).

Adaptation, Physiological↗
PubMed2001

Evaluation of a vertical flat-plate photobioreactor for outdoor biomass production and carbon dioxide bio-fixation: effects of reactor dimensions, irradiation and cell concentration on the biomass productivity and irradiation utilization efficiency.

Outdoor culture of the thermophilic cyanobacterium Synechocystis aquatilis SI-2 with a vertical flat-plate photobioreactor (VFPP) was studied during the period of January to August of 1999 in the northern region of Japan (Kamaishi, Iwate, 39 degrees N, 142 degrees E). The aim of this study was to investigate the CO2 fixation ability of the VFPP device under various irradiation conditions. An average biomass productivity of over 30 g m(-2) day(-1), which corresponds to a CO2 fixation rate of 50 g m(-2) day(-1), was achieved during this period with a 192-l scale culture. The effects on biomass productivity of the light path, height of the reactor, cell concentration and irradiation were also investigated. Variation of the optimal cell concentration to achieve the highest productivity for outdoor operation is discussed. A cell concentration of 1-2 g l(-1) was found to be most suitable for the irradiation range of 1-12 MJ m(-2) day(-1) under the experimental conditions used.

Biomass↗
PubMed2005

Production of 1,3-Propanediol by Clostridium butyricum VPI 3266 in continuous cultures with high yield and productivity.

The effects of dilution rate and substrate feed concentration on continuous glycerol fermentation by Clostridium butyricum VPI 3266, a natural 1,3-propanediol producer, were evaluated in this work. A high and constant 1,3-propanediol yield (around 0.65 mol/mol), close to the theoretical value, was obtained irrespective of substrate feed concentration or dilution rate. Improvement of 1,3-propanediol volumetric productivity was achieved by increasing the dilution rate, at a fixed feed substrate concentration of 30, 60 or 70 g l(-1). Higher 1,3-propanediol final concentrations and volumetric productivities were also obtained when glycerol feed concentration was increased from 30 to 60 g l(-1), at D=0.05-0.3 h(-1), and from 60-70 g l(-1), at D=0.05 and 0.1 h(-1).30 g l(-1) of 1,3-propanediol and the highest reported value of productivity, 10.3 g l(-1) h(-1), was achieved at D=0.30 h(-1) and 60 g l(-1) of feed glycerol. A switch to an acetate/butyrate ratio higher than one was observed for 60 g l(-1) of feed glycerol and a dilution rate higher than 0.10 h(-1); moreover, at D=0.30 h(-1) 3-hydroxypropionaldehyde accumulation was observed for the first time in the fermentation broth of C. butyricum.

Acetates↗
PubMed1985

End product inhibition of hepatic 25-hydroxyvitamin D production in the rat: specificity and kinetics.

The role of vitamin D metabolites in the regulation of hepatic 25-hydroxyvitamin D production was investigated by examining the effects of 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, and 24,25-dihydroxyvitamin D on the synthesis of [25-3H]hydroxyvitamin D by rachitic rat liver homogenates. Production of [25-3H]hydroxyvitamin D was inhibited by 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D, but not by 24,25-dihydroxyvitamin D. 25-Hydroxyvitamin D increased the Km of the vitamin D-25-hydroxylase enzyme(s), while 1,25-dihydroxyvitamin D decreased the Vmax with a Ki of 88.7 ng/ml. Inhibition of hepatic 25-hydroxyvitamin D production by 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D may be another control mechanism to regulate circulating vitamin D levels.

24,25-Dihydroxyvitamin D 3↗
PubMed1986

Effects of various inhibitors of oxidative phosphorylation on energy metabolism, macromolecular synthesis and cyclic AMP production in isolated rat thymocytes. A regulating role for the cellular energy state in macromolecular synthesis and cyclic AMP production.

Inhibitors of oxidative phosphorylation such as several triorganotin compounds, oligomycin, 2,4-dinitrophenol and carbonylcyanide p-trifluoromethoxyphenylhydrazone suppress energy metabolism of isolated rat thymocytes as indicated by a reduction of ATP levels, an increase in glucose consumption and by a marked accumulation of lactate. Also these compounds effectively inhibit the incorporation of DNA, RNA and protein precursors into acid-precipitable material of thymocytes. Moreover, the prostaglandin E1-induced elevation of cAMP is markedly reduced by these inhibitors. A correlation is observed between the effects on energy metabolism, macromolecular synthesis and cAMP production, since from a series of trialkyltin chlorides, tri-n-propyltin, tri-n-butyltin and tri-n-hexyltin are very effective inhibitors of these functions, while trimethyltin and tri-n-octyltin affect neither of them; other inhibitors of oxidative phosphorylation, each of them with quite different mechanisms of action, also inhibit macromolecular synthesis and cAMP production. The finding that a rise in intracellular ATP concentrations leads to a reversion of the tri-n-butyltin-induced inhibition of cAMP production and uridine incorporation, indicates a regulating role for the cellular energy state in these aspects of cellular function.

2,4-Dinitrophenol↗
PubMed1983

The production of liquid crystalline product phases by pancreatic lipase in the absence of bile salts. A freeze-fracture study.

The hydrolysis of gum arabic-stabilized trioleylglycerol emulsions by pancreatic lipase was examined by freeze-fracture electron microscopy in the absence of bile salts. A sequence of liquid crystalline product phases was produced during the non-equilibrium conditions of hydrolysis. The morphology of the product phases were pH- and droplet size-dependent. At pH 8.3 the initial product phase was composed of homogeneous spherical vesicles regardless of trioleylglycerol drop size. As the reaction progressed the partially hydrolyzed droplets showed a crystalline 'crust' and a true lamellar phase which was often swollen, giving an isotropic appearance to this phase. Some droplets demonstrated a possible transitory hexagonal phase composed of tubular-lamellar elements in close association with the oil phase. These tubular-lamellar elements graded into a lamellar phase at the aqueous/product interface. A cubic phase was not discernible. At pH 7.0 a single phase was seen which covered the drop surface with an amorphous layered 'crust'. The significance of these phases is discussed in relation to those produced by pure and mixed lipids under equilibrium conditions.

Animals↗
PubMed1984

Mast cell products stimulate collagenase and prostaglandin E production by cultures of adherent rheumatoid synovial cells.

Mast cells were purified from histologically-confirmed dog mastocytomas and extracted for whole mast cell products (MCP). When added to cultures of human adherent rheumatoid synovial cells MCP induced a 50-400 fold increase in prostaglandin E synthesis and a 10-50 fold stimulation of collagenase production. The mast cell stimulatory factor has not been identified and was not due to histamine, heparin or prostaglandin E. These results indicate a novel way in which mast cells might interact with synovial cells to promote the production of inflammatory mediators and proteolytic enzymes which might contribute to connective tissue degradation.

Animals↗
PubMed1989

Production and characterization of antibodies to advanced glycation products on proteins.

Antibodies directed against advanced glycation products formed during Maillard reaction have been generated and characterized. These antibodies reacted specifically with advanced glycation products in common among proteins incubated with glucose, but not early-stage compounds such as a Schiff base adduct and Amadori rearrangement products. Incubation of bovine serum albumin with glucose caused a time-related increase in immunoreactivity and a concomitant increase in fluorescence intensity. These antibodies may serve as a useful tool to elucidate pathophysiological roles of advanced Maillard reaction in diabetic complications and aging processes.

Antibodies↗