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At least 829 records · Page 46Linked to original sources
PubMed1993

Productive and non-productive phases during long-term persistence of influenza C virus.

Persistent infection with a variant of influenza C/Ann Arbor/1/50 virus in MDCK cells has been previously reported. However, the precise molecular mechanism of persistence is still unknown. We show that the release of active progeny virus, as tested for by haemagglutination and acetylesterase profiles, does not take place in freshly seeded MDCK cells. Productive virus replication occurs simultaneously with massive production of structural proteins as shown by immunoprecipitation and immunofluorescence. PCR for the HEF structural protein-encoding segment 4 revealed that positive-sense RNA is present only during virus multiplication whereas negative-sense RNA appears to be constantly detectable. In this study we give initial evidence that influenza C virus can persist in the form of its genomic minus strand RNA, and plus strand transcription, protein synthesis and virus replication remain restricted to productive phases.

Animals↗
PubMed1987

Effect of temperature on the stability of plasmid pTG201 and productivity of xylE gene product in recombinant Escherichia coli: development of a two-stage chemostat with free and immobilized cells.

The effect of temperature on the stability of pTG201, a plasmid carrying the xylE gene (which encodes catechol 2,3-dioxygenase from Pseudomonas putida), and the production of catechol 2,3-dioxygenase in free and immobilized Escherichia coli during continuous culture have been studied at various temperatures. Immobilization of cells increased the stability of pTG201 considerably, even under conditions when expression of the xylE product was enhanced. Since xylE transcription was controlled by the lambda PR promoter and cI857 repressor, increasing derepression temperatures increased catechol 2,3-dioxygenase productivity and decreased pTG201 stability. A two-stage continuous culture system to overcome the impact of the high-level expression of the xylE gene on the stability of pTG201 is described. In the first stage, immobilized cells were grown in the repressed state in order to prevent loss of pTG201, whereas in the second stage, cultures were maintained in the derepressed state.

Catechol 2,3-Dioxygenase↗
PubMed1971

Ethylene production by plant cell cultures: the effect of auxins, abscisic Acid, and kinetin on ethylene production in suspension cultures of rose and ruta cells.

Cell suspension cultures of Ruta graveolens (rue) and Rosa sp. produce ethylene. Both cultures grow at a high rate in hormone-free media. The rose cells are undifferentiated while the Ruta cells differentiate and form shoots after extended culture in hormone-free medium. Addition of 2,4-dichlorophenoxyacetic acid stimulated ethylene production in Ruta cells but not in rose cells. Abscisic acid (ABA) inhibited growth and ethylene production in rose, but only ethylene production in Ruta cells. Addition of kinetin reversed the inhibition by abscisic acid in the rose cells but not in the Ruta cells. The results suggested a distinct physiological difference between the two cultures. The Ruta cells responded to the growth regulators in a manner similar to whole plants.

Journal Article↗
PubMed1991

The products of Rhizobium genes, psi and pss, which affect exopolysaccharide production, are associated with the bacterial cell surface.

Translational fusions between a mutant phoA (lacking its promoter, ribosomal binding site and signal peptide sequence) and Rhizobium 'symbiotic' genes were isolated. Since these fusions expressed alkaline phosphatase (AP), the product of phoA, the genes into which phoA was inserted apparently specify proteins located in the bacterial periplasm or cell membrane, the compartment in which AP has activity. These genes were psiA and genes upstream of psiA (psiA is required for normal nodule development and strains with multicopy psiA fail to make exopolysaccharide (EPS) and to nodulate). Fusions between phoA and pss (exo) genes, which are required for EPS production, also resulted in the expression of AP indicating that products of these pss genes were located at the cell surface. Using gus fusions to psiA and pssA, we found that the former was expressed in N2-fixing bean root nodules but the latter was not.

Alkaline Phosphatase↗
PubMed2006

Company reference estimates for productivity loss due to migraine and productivity gains using rizatriptan 10 mg in Germany.

The prevalence of migraine in Germany is up to 14% in the female and up to 8% in the male population and peaks between the age of 35 and 45. Few studies have investigated the productivity loss and resulting costs attributable to migraine in Germany or addressed the question whether these costs can be reduced by optimal treatment. In recent years, 5-HT(1B/D) agonists (so-called triptans), a generation of drugs highly specific for migraine treatment, have been introduced. Seven 5-HT(1B/D) agonists have been approved in Germany with more than 20 dosage forms. We present a model that enables employers to estimate the annual cost of migraine and the annual cost that could be saved by treatment of migraine with rizatriptan compared with the use of non-specific antimigraine medication. A representative German company with 10,000 employees is used for the reference case analysis. This company is predicted to have 580 female and 284 male employees with migraine. These employees are estimated to lose 6992 workdays or 31.8 person years of productive effort annually due to migraine, valued approximately 1,431,719 euros. The value of work loss that could be avoided by treating migraine with rizatriptan is estimated at 619,094 euros annually. These data indicate that costs arising from lost productivity can be reduced by treating migraine headaches with a triptan.

Absenteeism↗
PubMed1994

Display of expression products of cDNA libraries on phage surfaces. A versatile screening system for selective isolation of genes by specific gene-product/ligand interaction.

Techniques for cloning cDNAs from bacteriophage libraries immobilised on solid supports are well established. However, these techniques do not allow selective enrichment of clones expressing proteins of interest. Screening of cDNA libraries would be simplified if the proteins encoded by cDNAs could be expressed on the surface of phage. Phage carrying genes encoding proteins for which a ligand is available can be selected directly by affinity interaction [Crameri, R. & Suter, M. (1993) Gene (Amst.) 137, 69-75]. The expression products from a cDNA library from Aspergillus fumigatus have been displayed on the surface of the filamentous phage M13 and screened for gene products binding to human serum IgE. The physical linkage of cDNA-encoded proteins to the genetic information required for their production, achieved by exploiting the high-affinity interaction of the Jun and Fos leucine zippers, allows screening of up to 1 x 10(10) independent clones in 50-microliters aliquots applied to a well of a microtiter plate coated with the ligand. Phage displaying IgE-binding proteins were selectively enriched 10(5)-10(6)-fold over non-specific phage after six rounds of growth and selection. The apparent molecular mass of the proteins selected from the cDNA library was in the range 20-40 kDa. Restriction enzyme analysis and preliminary sequence determination of 12 selected inserts revealed different sequences. The ability of the proteins to bind to human serum IgE was corroborated by enzyme-linked immunosorbent assay and by Western-blot analysis. The developed cloning strategy allows isolation of cDNAs encoding proteins for which a ligand is available and circumvents immobilisation of the libraries on solid-phase supports which hamper selective enrichment of clones expressing the desired protein.

Aspergillus fumigatus↗
PubMed1998

In vivo human melanoma cytokine production: inverse correlation of GM-CSF production with tumor depth.

Melanomas produce multiple cytokines which may influence their growth in vivo. Experimental evidence suggests that granulocyte macrophage-colony stimulating factor (GM-CSF) can induce a potent anti-melanoma response. whereas interleukin-8 (IL-8) may act as a growth factor in human melanoma. Little is currently known regarding the production of these cytokines by human melanoma in vivo. In this study we tested the hypothesis that endogenous production of GM-CSF and IL-8 can be correlated with the depth of human malignant melanoma surgical specimens. We examined 45 melanocytic human tissue samples consisting of 27 primary cutaneous melanomas, 9 metastatic melanomas, and 9 dysplastic nevi for in vivo GM-CSF and IL-8 production using immunohistochemistry. The majority of thin melanomas (< or = 0.76 mm) stained highly positive for GM-CSF with little or no staining for IL-8 whereas the medium (>0.76- < or = 4.0 mm) and thick (>4.0 mm) melanoma specimens showed little or no staining for GM-CSF and significant amounts of IL-8 staining. Metastatic melanoma as well as dysplastic nevi specimens had little or no GM-CSF and IL-8 staining. These results support the hypothesis that endogenous melanoma cytokines such as GM-CSF and IL-8 with opposing effects on tumor progression play an important role in melanoma growth and regulation.

Biomarkers, Tumor↗
PubMedDate not supplied

Calculations of total activity and relative radiolysis product yields for selected photonuclear reaction target systems used for production of clinically useful, short-lived, positron-emitting radionuclides.

The potential performance of certain photonuclear target systems designed to produce short-lived positron emitters for nuclear medicine applications was evaluated. Included were calculations of photonuclear target activity yields, relative radiolysis product yields and relative specific activities of products as a function of photonuclear target shapes, dimensions, spacing from the bremsstrahlung photon source, and the energy of the electron beam using the reactions 12C(gamma,n)11C, 14N(gamma,n)13N, and 16O(gamma,n)15O. Results indicate that substantial activity yields can be achieved in these photonuclear target systems and that specific activity of the product varies widely as a function of the energy of the electron beam used to produce the bremsstrahlung and the included angle from the central beam axis that the photonuclear target occupies. Results indicate that several commercial radiotherapy accelerators appear to have electron beam energy and current capabilities suitable for producing multiple mCi (1 mCi = 3.7 X 10(7) Bq) amounts of the above radionuclides.

Electrons↗
PubMed1999

Evidence for the distortion product frequency place as a source of distortion product otoacoustic emission (DPOAE) fine structure in humans. I. Fine structure and higher-order DPOAE as a function of the frequency ratio f2/f1.

Critical experiments were performed in order to validate the two-source hypothesis of distortion product otoacoustic emissions (DPOAE) generation. Measurements of the spectral fine structure of DPOAE in response to stimulation with two sinusoids have been performed with normal-hearing subjects. The dependence of fine-structure patterns on the frequency ratio f2/f1 was investigated by changing f1 or f2 only (fixed f2 or fixed f1 paradigm, respectively), and by changing both primaries at a fixed ratio and looking at different order DPOAE. When f2/f1 is varied in the fixed ratio paradigm, the patterns of 2 f1-f2 fine structure vary considerably more if plotted as a function of f2 than as a function of fDP. Different order distortion products located at the same characteristic place on the basilar membrane (BM) show similar patterns for both, the fixed-f2 and fDP paradigms. Fluctuations in DPOAE level up to 20 dB can be observed. In contrast, the results from a fixed-fDP paradigm do not show any fine structure but only an overall dependence of DP level on the frequency ratio, with a maximum for 2f1-f2 at f2/f1 close to 1.2. Similar stimulus configurations used in the experiments have also been used for computer simulations of DPOAE in a nonlinear and active model of the cochlea. Experimental results and model simulations give strong evidence for a two-source model of DPOAE generation: The first source is the initial nonlinear interaction of the primaries close to the f2 place. The second source is caused by coherent reflection from a re-emission site at the characteristic place of the distortion product frequency. The spectral fine structure of DPOAE observed in the ear canal reflects the interaction of both these sources.

Acoustic Stimulation↗
PubMed2006

New recombinant Escherichia coli strain tailored for the production of poly(3-hydroxybutyrate) from agroindustrial by-products.

A recombinant E. coli strain (K24K) was constructed and evaluated for poly(3-hydroxybutyrate) (PHB) production from whey and corn steep liquor as main carbon and nitrogen sources. This strain bears the pha biosynthetic genes from Azotobacter sp. strain FA8 expressed from a T5 promoter under the control of the lactose operator. K24K does not produce the lactose repressor, ensuring constitutive expression of genes involved in lactose transport and utilization. PHB was efficiently produced by the recombinant strain grown aerobically in fed-batch cultures in a laboratory scale bioreactor on a semisynthetic medium supplemented with the agroindustrial by-products. After 24 h, cells accumulated PHB to 72.9% of their cell dry weight, reaching a volumetric productivity of 2.13 g PHB per liter per hour. Physical analysis of PHB recovered from the recombinants showed that its molecular weight was similar to that of PHB produced by Azotobacter sp. strain FA8 and higher than that of the polymer from Cupriavidus necator and that its glass transition temperature was approximately 20 degrees C higher than those of PHBs from the natural producer strains.

Agriculture↗
PubMed1997

Poly(3-Hydroxybutyrate) Production with High Productivity and High Polymer Content by a Fed-Batch Culture of Alcaligenes latus under Nitrogen Limitation.

Alcaligenes latus has been known to produce poly(3-hydroxybutyrate) (PHB) in a growth-associated manner even under nutrient-sufficient conditions. However, the PHB content obtained by fed-batch culture was always low, at ca. 50%, which makes the recovery process inefficient. In this study, the effect of applying nitrogen limitation on the production of PHB by A. latus was examined. In flask and batch cultures, the PHB synthesis rate could be increased considerably by applying nitrogen limitation. The PHB content could be increased to 87% by applying nitrogen limitation in batch culture, which was considerably higher than that typically obtainable (50%) under nitrogen-sufficient conditions. In fed-batch culture, cells were first cultured by the DO-stat feeding strategy without applying nitrogen limitation. Nitrogen limitation was applied at a cell concentration of 76 g (dry cell weight)/liter, and the sucrose concentration was maintained within 5 to 20 g/liter. After 8 h of nitrogen limitation, the cell concentration, PHB concentration, and PHB content reached 111.7 g (dry cell weight)/liter, 98.7 g/liter, and 88%, respectively, resulting in a productivity of 4.94 g of PHB/liter/h. The highest PHB productivity, 5.13 g/liter/h, was obtained after 16 h.

Journal Article↗
PubMed2005

Protamylasse, a residual compound of industrial starch production, provides a suitable medium for large-scale cyanophycin production.

Protamylasse is a residual compound occurring during the industrial production of starch from potatoes. It contains a variety of nutrients and all necessary minerals and could be used as a carbon, nitrogen, and energy source for the growth of bacteria and also for cyanophycin (CGP) biosynthesis. Media containing protamylasse as the sole compound diluted only in water were therefore examined for their suitability in CGP production. Among various bacterial strains investigated in this study, a recombinant strain of Escherichia coli DH1 harboring plasmid pMa/c5-914::cphA6803, which carries the cyanophycin synthetase structural gene (cphA) from Synechocystis sp. strain PCC6803, was found to be most suitable. Various cultivation conditions for high CGP contents were first optimized in shake flask cultures. The optimized conditions were then successfully applied to 30- and 500-liter fermentation scales in stirred tank reactors. A maximum CGP content of 28% (wt/wt) CGP per cell dry matter was obtained in 6% (vol/vol) protamylasse medium at an initial pH of 7.0 within a cultivation period of only 24 h. The CGP contents obtained with this recombinant strain employing protamylasse medium were higher than those obtained with the same strain cultivated in mineral salts medium or in expensive commercial complex media such as Luria-Bertani or Terrific broth. It was shown that most amino acids present in the protamylasse medium were almost completely utilized by the cells during cultivation. Exceptions were alanine, tryptophan, tyrosine, and most interestingly, arginine. Furthermore, CGP was easily isolated from protamylasse-grown cells by applying the acid extraction method. The CGP exhibited a molecular mass of about 26 to 30 kDa and was composed of 50% (mol/mol) aspartate, 46% (mol/mol) arginine, and 4% (mol/mol) lysine. The use of cheap residual protamylasse could contribute in establishing an economically and also ecologically feasible process for the biotechnological production of CGP.

Amino Acids↗
PubMed1970

Effect of exogenous interferon on rubella virus production in carrier cultures of cells defective in interferon production.

An established cell line (Vero) defective in interferon production was used to evaluate the role of interferon in chronic rubella virus infections of cell cultures. Inoculation of Vero cells with a low multiplicity of virus resulted in the development of carrier cultures which had the characteristics of a regulated infection. Although added interferon did not alter rubella virus production in carrier cultures of cells capable of producing interferon, such added interferon caused a dramatic reduction of virus production in the carrier cultures of Vero cells. There was a reduction of the fraction of cells producing virus in Vero carrier cultures, but not in carrier cultures of other cells upon incubation in the continual presence of rubella virus antibodies. In addition, the fraction of infected cells fluctuated in carrier cultures in Vero cells. The data indicate that interferon is not necessary for maintaining a chronic rubella virus infection in vitro and suggest an instability of the virus genome in Vero cells.

Journal Article↗
PubMed1982

Gamma interferon production in allogeneic stimulation: antigenicity that is sufficient to cause interferon production.

Spleen cells obtained from allogeneic cell-primed mice produced immune interferon when cocultivated with the antigenic cells. The purpose of this study was to clarify the antigenic determinants for immune interferon production in this allogeneic stimulation system. An incompatibility at the K end alone or at the D end alone of the H-2 complex was sufficient for immune interferon induction. No interferon production was observed in the combinations between strains of mice that differ for the non-H-2 regions, including the M locus. Immune interferon-producing cells (IIPC), induced by difference of the H-2K or H-2D regions, recognized the specificities controlled by the H-2K or H-2D regions, respectively; namely, there was no cross-reaction between the two regions. The difference between H-2d and H-2b did not cause interferon production in the combinations of which non-H-2 regions were very similar to each other. IIPC were not induced in the combination, but when IIPC were properly induced in B6 spleen cells, the IIPC could recognize the specificities controlled by the H-2d region (B10D2) and produced immune interferon.

Animals↗
PubMed1995

Growth hormone activation of human monocytes for superoxide production but not tumor necrosis factor production, cell adherence, or action against Mycobacterium tuberculosis.

We have previously demonstrated that growth hormone (GH) is a human macrophage-activating factor which primes monocytes for enhanced production of H2O2 in vitro. This report extends our observations to other monocyte functions relevant to infection. We find that GH also primes monocytes for O2- production, to a degree similar to the effect of gamma interferon. Neither macrophage-activating factor alone stimulates monocytes to release bioactive tumor necrosis factor. However, GH, unlike gamma interferon, does not synergize with endotoxin for enhanced tumor necrosis factor production. In further contrast, GH does not alter monocyte adherence or morphology, while phagocytosis and killing of Mycobacterium tuberculosis by GH-treated monocytes are also unaffected. Therefore, despite the multiplicity of the effects of GH on the immune system in vivo, its effects on human monocytes in vitro appear to be limited to priming for the release of reactive oxygen intermediates.

Blood Bactericidal Activity↗
PubMed1996

Neurotoxicity of glia activated by gram-positive bacterial products depends on nitric oxide production.

The present study examined the mechanism by which bacterial cell walls from two gram-positive meningeal pathogens, Streptococcus pneumoniae and the group B streptococcus, induced neuronal injury in primary cultures of rat brain cells. Cell walls from both organisms produced cellular injury to similar degrees in pure astrocyte cultures but not in pure neuronal cultures. Cell walls also induced nitric oxide production in cultures of astrocytes or microglia. When neurons were cultured together with astrocytes or microglia, the cell walls of both organisms became toxic to neurons. L-NAME, a nitric oxide synthase inhibitor, protected neurons from cell wall-induced toxicity in mixed cultures with glia, as did dexamethasone. In contrast, an excitatory amino acid antagonist (MK801) had no effect. Low concentrations of cell walls from either gram-positive pathogen added together with the excitatory amino acid glutamate resulted in synergistic neurotoxicity that was inhibited by L-NAME. The induction of nitric oxide production and neurotoxicity by cell walls was independent of the presence of serum, whereas endotoxin exhibited these effects only in the presence of serum. We conclude that gram-positive cell walls can cause toxicity in neurons by inducing the production of nitric oxide in astrocytes and microglia.

Animals↗
PubMed1997

Interleukin-12 suppresses immunoglobulin E production but enhances immunoglobulin G4 production by human peripheral blood mononuclear cells.

The effect of interleukin-12 (IL-12) on human immunoglobulin G4 (IgG4) and IgE production was examined with cells derived from filarial patients and European controls. IL-12 inhibited IgE release but enhanced IgG4 production in cultures of peripheral blood mononuclear cells stimulated with anti-CD2 plus IL-2. When purified T- and B-cell cocultures were examined, IL-12 again markedly enhanced IgG4, whereas IgE production was no longer inhibited.

Animals↗
PubMed2001

Human neutrophils and their products induce Shiga toxin production by enterohemorrhagic Escherichia coli.

The Shiga toxins (Stx) are critical virulence factors for Escherichia coli O157:H7 and other serotypes of enterohemorrhagic E. coli (EHEC). These potent toxins are encoded in the genomes of temperate lambdoid bacteriophages. We recently demonstrated that induction of the resident Stx2-encoding prophage in an O157:H7 clinical isolate is required for toxin production by this strain. Since several factors produced by human cells, including hydrogen peroxide (H2O2), are capable of inducing lambdoid prophages, we hypothesized that such molecules might also induce toxin production by EHEC. Here, we studied whether H2O2 and also human neutrophils, an important endogenous source of H2O2, induced Stx2 expression by an EHEC clinical isolate. Both H2O2 and neutrophils were found to augment Stx2 production, raising the possibility that these agents may lead to prophage induction in vivo and thereby contribute to EHEC pathogenesis.

Diarrhea↗