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At least 757 records · Page 42Linked to original sources
PubMed1983

Suppression of IgE antibody production in SJL mice. V. Effect of irradiation and adult thymectomy on the suppression of IgE antibody production in SJL mice.

Anti-DNP IgE antibody production was low and transient in SJL mice which were immunized with 1 microgram DNP-Nb and 1 mg A1(OH)3. The immunized SJL mice were irradiated (60-540 R) 1 day after challenge. A dose higher than 180 R induced enhancement of anti-DNP IgE antibody production as compared to nonirradiated control mice, suggesting the existence of irradiation-sensitive suppressor cells. Anti-DNP IgE antibody production was suppressed when immunized and irradiated SJL mice were injected with spleen cells from adult-thymectomized SJL mice. The donors of the spleen cells were thymectomized 2 or 4 months previously, and this suggests that the suppressor cells from unprimed mice are long-living T cells.

Animals↗
PubMed1990

Identification of a cord blood T cell subset of CD3+4-8-45R+ suppressing interleukin 2 production in the autologous mixed lymphocyte reaction and the mode of action of exogenous IL2 in the induction of IL2 production.

As previously reported, the inability of cord blood T cells to produce IL2 in the autologous mixed lymphocyte reaction (AMLR) could be recovered by the treatment of stimulator non-T cells with interferon-gamma (IFN-gamma) and of the AMLR with exogenous IL2. In the present study, we showed that addition of untreated autologous cord blood T cells to the above-mentioned AMLR abrogated the IL2 production in a dose-dependent manner, suggesting active suppression by the untreated T cells because untreated cord blood T cells did not consume IL2. Suppressor activity was abrogated by the treatment of cord blood T cells with monoclonal anti-CD3 antibody plus complement or with monoclonal anti-CD45R (Leu 18) antibody, but not by the treatment with monoclonal anti-CD4 antibody and/or anti-CD8 antibody plus complement. These data showed that the cord blood suppressor T cells were CD3+4-8-45R+. This suppressor activity also disappeared by culturing with rIL2 for 8 hr. As the frequency of CD45R+ cord blood T cells was comparable to that of CD45R+ adult T cells and was minimally affected by the IL2 treatment, functional modulation of CD45R+ suppressor T cells by IL2 is suggested. Moreover, in spite of the inhibitory effect of anti-CD45R antibody on the suppressor activity, IL2 production was not induced merely by addition of anti-CD45R antibody directly to the responder cells in AMLR. Taken together, these data suggest the requirement of exogenous IL2 for IL2 production in that IL2-producing-precursor T cells themselves should be stimulated by IL2 in addition to the modulation of CD45R+ suppressor T cells by IL2.

Adult↗
PubMed1984

The production of arachidonate lipoxygenase products by rat intestine is increased by phenolphthalein.

Rat isolated intestine incubated in Krebs solution converted exogenous [14C]arachidonic acid into products that chromatographed with prostaglandins, leukotriene B4 and 5-hydroxy-eicosatetraenoic acid. The accumulation of these products was increased by phenolphthalein 3.14-1570 microM and reduced by indomethacin 2.8 microM. This raises the possibility that laxation by phenolphthalein involves the formation of arachidonate lipoxygenase and cyclo-oxygenase products.

Animals↗
PubMed1996

Evaluation of hollow fiber bioreactors as an alternative to murine ascites production for small scale monoclonal antibody production.

The objective of this study was to compare monoclonal antibody production in hollow fiber bioreactor systems and murine ascites to determine the feasibility of the bioreactor system as a potential alternative to the use of mice. Three hybridoma cell lines were grown in each of three different hollow fiber bioreactor systems and in groups of 20 mice. Mice were primed with 0.5 ml pristane intraperitoneally 14 days prior to inoculation of 1X10(6) hybridoma cells. Each mouse was tapped a maximum of three times for collection of ascites. Ascites volumes and daily clinical observations were recorded. Bioreactors were harvested three times weekly for 65 day and were monitored by cell counts, cell viability and media glucose consumption. Time and materials logs were maintained. The total quantity of monoclonal antibody produced in 20 mice versus the mean production for the three different bioreactors in 65 days was as follows: cell line 2B11, 455 mg vs. 168 mg; cell line 3C9, 446 mg vs. 565 mg; and cell line RMK, 997 mg vs. 1023 mg. Mean monoclonal antibody concentration ranged from 4.07 to 8.37 mg/ml in murine ascites, and from 0.71 to 11.10 mg/ml in hollow fiber bioreactor system. Although time and material costs were generally greater for the bioreactors, these results suggest that hollow fiber bioreactor system merit further investigations as potentially viable in vitro alternatives to the use of mice for small scale (< 1 g) monoclonal antibody production.

Animals↗
PubMed1984

The enhancement of pregnenolone production as the main mechanism of the prolonged stimulatory effect of ACTH on cortisol production by guinea-pig adrenocortical cells.

The prolonged stimulatory influence of corticotropin (ACTH) on the adrenocortical steroidogenic response to ACTH was studied in guinea-pig adrenocortical cells harvested from control and ACTH-treated animals (ACTH1-24, 50 micrograms s.c. twice daily on the day preceding the in vitro experiment). The maximal capacity to produce cortisol in response to ACTH (by 10(5) cells and 2 h incubation) was increased from 341.8 +/- 36.3 ng (control group) to 663.3 +/- 37.6 ng for cells obtained from guinea-pigs treated in vivo with ACTH. In the presence of trilostane, added to the cells in order to block the conversion of pregnenolone to cortisol, the net maximal output of pregnenolone and 17-hydroxypregnenolone in response to ACTH was significantly increased in adrenocortical cells from ACTH-treated animals (449.5 +/- 35.8 ng pregnenolone and 85.7 +/- 10.5 ng 17-hydroxypregnenolone vs 269.1 +/- 36.3 ng pregnenolone and 43.7 +/- 8.51 ng 17-hydroxypregnenolone for cells from control guinea-pigs). It appeared therefore that the total production of pregnenolone (as estimated by the sum of pregnenolone and 17-hydroxypregnenolone produced by the cells incubated with trilostane) nearly reached the level of the maximal production of cortisol in response to ACTH and was also significantly enhanced for cells from ACTH-treated animals (532.2 +/- 38.4 ng vs 312.8 +/- 40.0 ng for cells from control group). By contrast, no effect was documented on 17 alpha-hydroxylase activity since 17 alpha-hydroxylation index was similar for both types of adrenocortical cells (16.3 +/- 2.05% for ACTH-treated animals and 14.2 +/- 2.83% for control group). It was concluded therefore that the prolonged stimulatory influence of ACTH on pregnenolone production is the main mechanism of the enhancement of cortisol synthesis by guinea-pig adrenocortical cells previously stimulated by ACTH.

17-alpha-Hydroxypregnenolone↗
PubMed1993

A step in the process of prostacyclin production whose decline leads to the age-related decrease in production by human umbilical vein endothelial cells in culture.

Human umbilical vein endothelial (HUVE) cells were examined at various culture ages for four steps of prostacyclin (PGI2) production ((1) incorporation of exogenous arachidonic acid into the cell membrane, (2) loss of arachidonic acid from the cell membrane to the cytoplasm, (3) conversion of arachidonic acid to PGI2 in the cytoplasm, (4) release of PGI2 to the outside of the cell) to determine the step whose decline leads to the age-related decrease in PGI2 production. Only conversion to PGI2 (step 3) showed the age-related decrease. Judging from these results, the authors conclude that the age-related decrease in PGI2 production is mainly due to the decrease in the ability of HUVE cells to convert arachidonic acid to PGI2 in the cytoplasm.

Aging↗
PubMed1985

Lipoxygenase products: leukotrienes C4, D4, A4's breakdown products and 12-HPETE influence platelet aggregation in vivo.

Clinical and pathological observations of diseases concomitant which leukotriene release show consistently an involvement of platelet activation. This effect was hitherto believed to be due to tissue trauma. The aim of the present study was to elucidate whether lipoxygenase products such as leukotrienes C4, D4, 12-HPETE and the breakdown products of leukotriene A4 have a direct pro-aggregatory property of their own. Platelet aggregation was induced by intravascular excitation of fluoresceiniso-thiocyanate-dextran in arterioles of the hamster cheek pouch. "Time to aggregate appearance" was assessed prior and after parenteral application of the studied compounds. LTA4's breakdown products were found to have anti-aggregatory properties, whereas LTC4, D4 and 12-HPETE enhanced platelet aggregability.

Animals↗
PubMed1995

Enhancement of antigen-specific antibody production by extracellular slime products from slime-forming Lactococcus lactis subspecies cremoris SBT 0495 in mice.

The effect of extracellular slime products (ESP) produced by Lactococcus lactis subspecies cremoris SBT 0495 on antigen specific antibody production was studied in mice. ESP contained 48.5% protein, 15.4% neutral sugar, and 1.1% of phosphorus. The optimum dose of ESP was between 100 to 500 micrograms per mouse. ESP administered intraperitoneally (200 micrograms per mouse) enhanced the production of specific antibody in mice. These results indicate that ESP may act as an adjuvant.

Animals↗
PubMed1992

Improving the production of E. coli beta-lactamase in Bacillus subtilis: the effect of glucose, pH and temperature on the production level.

Bacillus subtilis has been considered a promising host for the production of foreign proteins. However, proteases released by the host organism can often cause rapid breakdown of secreted heterologous proteins. Here we report that the addition of 6% glucose and 100 mM potassium phosphate to the growth medium significantly reduces the degradation of E. coli TEM beta-lactamase secreted from B. subtilis, when applying an expression system based on B. amyloliquefaciens alpha-amylase. The yield of beta-lactamase was increased 10-20-fold when compared to the yield in Luria medium. The promoter of B. amyloliquefaciens alpha-amylase gene is repressed by glucose. However, here we show that the repression does not take place in a multicopy plasmid, thus enabling our approach to efficiently reduce the protease action by catabolite repression. We have also studied the role of pH and temperature on the beta-lactamase production in laboratory scale bioreactors. Low temperature and low pH are both favorable for a high level beta-lactamase production by the high copy plasmid construction.

Bacillus subtilis↗
PubMed1991

The waste-product theory of aging: simulation of metabolic waste production.

A mathematical model of cellular metabolism is used to relate the rates of cell division and waste production to the concentrations of oxygen and glucose in the medium in which a normal diploid cell culture is grown. The metabolic model in tandem with an earlier waste-content model based on the waste-product theory of aging provides a unified cell-culture model with which population size and intracellular waste content can be calculated. Population size is measured by the number of population doublings which have been achieved. After suitable adjustment of parameters in the metabolic model, maximum values of population size are calculated numerically with the use of the unified model. Results show that the population maxima are related in a plausible way to the oxygen and glucose concentrations. The effects of temperature changes and contact inhibition of growth are also simulated. Small changes in the cell-division and waste-production rates can cause transformation to unlimited growth in the waste-content model, but the unified model is not correspondingly sensitive to changes in the oxygen and glucose concentrations or to changes in temperature.

Cell Division↗
PubMed1994

Biological safety considerations in the production of health care products from recombinant organisms.

Safety considerations in the field of recombinant technology and rDNA production of health care products have been under discussion since the beginning of this technology in 1973 and will certainly go on. However no adverse effects, which could have been attributed to rDNA technology have been observed. On the other hand many life-saving and life-improving drugs have been on the market for many years to the benefit of many patients. New technologies and products thereof often provoke uncertainties about their impact on the environment or society. This article discusses some potential risks in the application of rDNA technology to drugs as well as some benefits for patients, society and environment.

Journal Article↗
PubMed1993

In-target production of [13N]ammonia: target design, products, and operating parameters.

[13N]Ammonia, commonly used in PET, has been prepared in good yield in the target. Up to 800 mCi of radiopharmaceutical was obtained by in-line processing of the irradiated water. Relatively low hydrogen pressure was used to control the target chemistry. Target designs and the product dependence on beam dose, dose rate and pressure are reported. Ethanol as a target additive was also investigated. Hydrogen and ethanol together were more effective than either alone at high beam dose. Parameters are reported for production needs from single doses to synthetic applications. An incidental method for production of [13N]nitrogen gas is also reported.

Ammonia↗
PubMed2006

Modulating effects of a novel skin-lightening agent, alpha-lipoic acid derivative, on melanin production by the formation of DOPA conjugate products.

Sodium zinc dihydrolipoylhistidinate (DHLHZn) is a compound of Zn(2+)/dihydrolipoic acid derivate complex, which was developed for cosmetic/medical use. To characterize DHLHZn as a novel skin-lightening agent, inhibitory actions of DHLHZn on tyrosinase (including its reaction pathway) have been elucidated in this study. In a B16 melanoma cell system, DHLHZn was active in suppressing the synthesis of melanins as well as alpha-arbutin, well known as a depigmenting drug. Furthermore, in a tyrosinase assay, DHLHZn showed stronger inhibitory effect on DOPAchrome formation than other tyrosinase inhibitors such as kojic acid. Our previous report demonstrated that the sulfhydryl groups of lipoyl motif react with DOPAquinone to form lipoyl DOPA conjugates. We therefore postulated that conjugated products between DHLHZn and DOPAquinone might be formed. Upon reaction of DHLHZn with L-DOPA following tyrosinase-catalyzed oxidation, the formation of DHLH DOPA conjugated products was confirmed by HPLC-tandem mass spectrometry using reserpine as the internal standard. In addition, the inhibitory kinetics analyzed by a Lineweaver-Burk plot exhibited the reversibility of DHLHZn as a competitive inhibitor with a KI value of 0.35 microM. These results indicate that this covalent reaction might contribute to alternating DOPAquinone, which is a tyrosinase reaction product, and result in the competitive inhibitory effect of DHLHZn on DOPAchrome formation. DHLHZn may thus serve as a potentially effective skin-lightening agent, an effectiveness that is based on the compound's covalent scavenging of DOPAquinone resulting in depigmentation.

Animals↗
PubMed2004

Increased norepinephrine production associated with burn injuries results in CCL2 production and type 2 T cell generation.

The susceptibility of thermally injured mice (TI-mice) to various infections is markedly influenced by burn-associated type 2 T cell responses, which are common with severe thermal injuries. Previously, we have reported that CC chemokine ligand 2/monocyte chemoattractant protein-I (CCL2) is produced in mice within 1 day of thermal injury, and the subsequent development of burn-associated type 2 T cell responses are triggered by this chemokine produced early after thermal injury. In this study, influence of norepinephrine (NE) on CCL2 production in mice early after thermal injury (TI) was investigated. Peripheral blood mononuclear cells (PBMC) and peritoneal macrophages (PMphi) from TI-mice produced CCL2, but the same cell preparations from normal mice did not. This chemokine was not produced by PBMC and PMphi from TI-mice previously treated with 6-hydroxydopamine (6-OHDA), which destroys sympathetic nerve termini. NE production was increased in circulation of TI-mice, and treatment of TI-mice with 6-OHDA resulted in the inhibition of NE secretion. When PBMC from normal mice were treated with NE, they acquired the ability to produce CCL2. Splenic T cells from TI-mice produced IL-4 into their culture fluids, while the cytokine was not produced by splenic T cells from TI-mice previously treated with 6-OHDA. These results indicate that NE may have an important role on early CCL2 production and the subsequent development of burn-associated type 2 T cell responses.

Animals↗
PubMed2004

Pretreatment with granulocyte-colony stimulating factor decreases lipopolysaccharide-induced interferon-gamma production in mice in association with the production of interleukin-18.

We studied the effects of pretreatment with granulocyte-colony stimulating factor (G-CSF) on the production of pro- and anti-inflammatory cytokines induced by lipopolysaccharide (LPS). Mice received G-CSF or control saline once a day for 7 days or once at 1 h before the injection of LPS. Cytokines were measured by enzyme-linked immunosorbent assay or antibody-based electrochemiluminescence assay and cytokine mRNA was measured by RNAse protection assay. Mice pretreated with G-CSF for 7 days before LPS had lower serum levels of LPS-induced interferon-gamma (IFN-gamma) and higher levels of interleukin (IL)-6 and IL-10 than controls. G-CSF-pretreated mice also had lower mRNA levels of IFN-gamma and higher mRNA levels of IL-6 and IL-10 in the spleen and/or liver than controls. G-CSF-pretreated mice had serum levels of tumor necrosis factor, IL-12 p70 and IL-12 p40 similar to controls. G-CSF-pretreated mice had lower levels of spleen IL-18 than controls-serum IL-18 being undetectable in mice after LPS-and lower levels of IL-18 mRNA in the spleen. Mice pretreated with G-CSF 1 h before LPS had lower levels of serum IFN-gamma and spleen IL-18 than controls. G-CSF pretreatment alters the expression of LPS-induced cytokines with a decrease in pro-inflammatory IFN-gamma and an increase in anti-inflammatory IL-6 and IL-10. G-CSF decrease of IL-18 production may be a major mechanism explaining the effects of G-CSF on the production of IFN-gamma.

Animals↗
PubMed2005

Application of bioreactor system for large-scale production of Eleutherococcus sessiliflorus somatic embryos in an air-lift bioreactor and production of eleutherosides.

Embryogenic callus was induced from leaf explants of Eleutherococcus sessiliflorus cultured on Murashige and Skoog (MS) basal medium supplemented with 1 mg l(-1) 2,4-dichlorophenoxyacetic acid (2,4-D), while no plant growth regulators were needed for embryo maturation. The addition of 1 mg l(-1) 2,4-D was needed to maintain the embryogenic culture by preventing embryo maturation. Optimal embryo germination and plantlet development was achieved on MS medium with 4 mg l(-1) gibberellic acid (GA(3)). Low-strength MS medium (1/2 and 1/3 strength) was more effective than full-strength MS for the production of normal plantlets with well-developed shoots and roots. The plants were successfully transferred to soil. Embryogenic callus was used to establish a suspension culture for subsequent production of somatic embryos in bioreactor. By inoculating 10 g of embryogenic cells (fresh weight) into a 3l balloon type bubble bioreactor (BTBB) containing 2l MS medium without plant growth regulators, 121.8 g mature somatic embryos at different developmental stages were harvested and could be separated by filtration. Cotyledonary somatic embryos were germinated, and these converted into plantlets following transfer to a 3l BTBB containing 2l MS medium with 4 mg l(-1) GA3. HPLC analysis revealed that the total eleutherosides were significantly higher in leaves of field grown plants as compared to different stages of somatic embryo. However, the content of eleutheroside B was highest in germinated embryos. Germinated embryos also had higher contents of eleutheroside E and eleutheroside E1 as compared to other developmental stages. This result indicates that an efficient protocol for the mass production of E. sessiliflorus biomass can be achieved by bioreactor culture of somatic embryos and can be used as a source of medicinal raw materials.

Bioreactors↗
PubMed2004

How do aldehyde side products occur during alkene epoxidation by cytochrome P450? Theory reveals a state-specific multi-state scenario where the high-spin component leads to all side products.

A theoretical study of alkene epoxidation, by the high-valent iron-oxo species (Compound I) of cytochrome P450, reveals a multi-state scenario in which the different products are generated in a state specific manner. All the low-spin doublet state processes are effectively concerted epoxide producing pathways. By contrast, all the high-spin quartet processes are stepwise and either lead to epoxide that does not conserve the isomeric identity of the alkene (cis or trans), or/and to by-products such as suicidal complexes and aldehydes. The product/state inventory is the following: (a) The epoxide with conserved alkene stereochemistry is generated from the low-spin doublet states of Compound I in a nonsynchronous but effectively concerted pathways that involve carbon radical (with Fe(III) and Fe(IV)) and cationic intermediates. (b) The epoxide with scrambled alkene stereochemistry is obtained from the quartet high-spin radical intermediate (with Fe(IV)). (c) The suicidal complex, with a C-N bond between the alkene and the porphyrin, is obtained from the high-spin cationic state that possesses one electron in the sigma xy* orbital (the antibonding Fe-N orbital made from dxy and nitrogen sigma-hybrids). (d) The aldehyde by-product is obtained from the high-spin cationic state that possesses one electron in the sigma xy* orbital (the antibonding O-Fe-S orbital made from dz2 and the oxo and sulfur sigma-hybrids). Factors controlling the competition between these processes are discussed.

Alkenes↗
PubMed2005

Production and characterization of monoclonal antibodies against excretory/secretory products of adult Echinococcus granulosus, and their application to coproantigen detection.

Two IgM murine monoclonal antibodies (MAbs), EgC1 and EgC3, were produced against the excretory/secretory (E/S) products of Echinococcus granulosus adult worms. Immunoblotting revealed that both predominantly recognized a 50 kDa antigen in the somatic extract and an 85 kDa component in the E/S products. Immunolocalization showed that both MAbs reacted with the tegument of the parasite, and additionally EgC3 reacted with parenchyma and the tegument lining the external surface of the reproductive organs. A coproantigen capture ELISA was developed using a rabbit polyclonal antibody against E/S products from adult tapeworms as catching antibodies, and each one of MAbs as detecting antibody. The assays detected seven out of eight (EgC1), and eight out of eight (EgC3) experimentally infected dogs (worm burdens ranging from 61 to 57,500), using heat-treated samples obtained at prepatent period, and none (n=8) of helminth-free samples. Time course analysis showed that, after a 12-25 days lag, coproantigen levels rose above cut off O.D. values and typically peaked around 30 days post-infection (DPI) at the end of the experiment. One dog experimentally infected with Taenia hydatigena metacestodes was slightly detected as positive at different time points after 30 DPI. Both MAbs showed a similar pattern of recognition, but T. hydatigena antigens were undetectable for a longer period, and reached lower O.D. values with EgC1. Interestingly, fecal samples from two experimentally infected dogs with Echinococcus multilocularis were not recognized by the EgC1 assay, suggesting a potential value as species-specific diagnostic tool.

Animals↗