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At least 847 records · Page 47Linked to original sources
PubMed1989

DNA sequence, products, and transcriptional pattern of the genes involved in production of the DNA replication inhibitor microcin B17.

The 3.8-kilobase segment of plasmid DNA that contains the genes required for production of the DNA replication inhibitor microcin B17 was sequenced. The sequence contains four open reading frames which were shown to be translated in vivo by the construction of fusions to lacZ. The location of these open reading frames fits well with the location of the four microcin B17 production genes, mcbABCD, identified previously through genetic complementation. The products of the four genes have been identified, and the observed molecular weights of the proteins agree with those predicted from the nucleotide sequence. The transcription of these genes was studied by using fusions to lacZ and physical mapping of mRNA start sites. Three promoters were identified in this region. The major promoter for all the genes is a growth phase-regulated OmpR-dependent promoter located upstream of mcbA. A second promoter is located within mcbC and is responsible for a low-level basal expression of mcbD. A third promoter, located within mcbD, promotes transcription in the reverse direction starting within mcbD and extending through mcbC. The resulting mRNA appears to be an untranslated antisense transcript that could play a regulatory role in the expression of these genes.

Amino Acid Sequence↗
PubMed1969

Inhibition of protease production of various bacteria by ammonium salts: its effect on toxin production and virulence.

Production of protease by many bacteria was found to be inhibited by ammonium salts, and the enzyme production was more sensitive to the salts than was growth of the organisms. Inhibition of protease production by some pathogenic bacteria may result in the recognition of an exotoxin which otherwise would have been digested by the protease. In the case of Pseudomonas aeruginosa, qualitatively different toxicities could be demonstrated in the culture fluids, depending on the presence or absence of protease in such a fluid. The toxicity of the culture in the presence of a high titer of protease may be due primarily to the protease, whereas the toxicity exhibited in the absence of protease could be due to proteinacious exotoxin. Producers of high titers of protease tended to be less virulent in vivo than producers of low titers of the enzyme, which exert their toxicities by a separate exotoxin.

Aeromonas↗
PubMed1973

The production and testing of staphylococci with clumping factor activity for use in the assay of fibrinogen degradation products.

A method for the large-scale production of a staphylococcal preparation for use in the assay of fibrinogen degradation products is described. The material is assayed against a fibrinogen standard and is shown to be stable over long periods and of high sensitivity. The possibility of production on an occasional basis in a routine laboratory is discussed.

Agglutinins↗
PubMed1983

Theoretical maximum and observed product yields associated with curdlan production by Alcaligenes faecalis.

As a guide to both strain and process improvement and based on certain assumptions concerning both glucose and energy metabolism of the process organism, Alcaligenes faecalis var. myxogenes, the theoretical "maximum" carbon (glucose) substrate to product conversion efficiency (i.e., product yield) has been estimated for "curdlan-type" beta(1 leads to 3)-glucan exopolysaccharide production in batch fermentations. Under nitrogen limitation, which promotes curdlan biosynthesis (mu = 0), the rate of glucose consumption for cellular maintenance energy (grams of glucose per gram of cells per hour) was approximately five times higher than under carbon limitation. The decrease in the theoretical "maximum" curdlan conversion efficiency of 74% to the average value of 50-56% was due primarily to the high maintenance coefficient of the nitrogen-starved culture.

Alcaligenes↗
PubMed2006

Hepatic glucose production is more sensitive to insulin-mediated inhibition than hepatic VLDL-triglyceride production.

Insulin is an important inhibitor of both hepatic glucose output and hepatic VLDL-triglyceride (VLDL-TG) production. We investigated whether both processes are equally sensitive to insulin-mediated inhibition. To test this, we used euglycemic clamp studies with four increasing plasma concentrations of insulin in wild-type C57Bl/6 mice. By extrapolation, we estimated that half-maximal inhibition of hepatic glucose output and hepatic VLDL-TG production by insulin were obtained at plasma insulin levels of approximately 3.6 and approximately 6.8 ng/ml, respectively. In the same experiments, we measured that half-maximal decrease of plasma free fatty acid levels and half-maximal stimulation of peripheral glucose uptake were reached at plasma insulin levels of approximately 3.0 and approximately 6.0 ng/ml, respectively. We conclude that, compared with insulin sensitivity of hepatic glucose output, peripheral glucose uptake and hepatic VLDL-TG production are less sensitive to insulin.

Animals↗
PubMed1986

Plasminogen activator production from murine mastocytoma cells. Dissociation of plasminogen activator and histamine production by sodium butyrate.

Plasminogen activator (PA) production from mouse mastocytoma P815 was investigated. A trace level of PA was detected in the culture supernatant of P815, but addition of Con A (5 micrograms/ml) stimulated the PA production to the 20- to 50-fold of that of the unstimulated culture. Time course studies suggest that PA is actively synthesized and secreted during the culture period with Con A. Furthermore, pretreatment of P815 with sodium butyrate, which is known to differentiate interleukin-3-dependent bone marrow mast cells or P815 cells, increased the PA production from P815 cells in the presence or absence of Con A.

Animals↗
PubMed1980

Cellular mechanisms for increased fetal hemoglobin production in culture. Evidence for continuous commitment to fetal hemoglobin production during burst formation.

Using microscopic immunodiffusion assays and microdensitometric analysis of pericellular immunoprecipitate, the percentage of nucleated erythrocytes containing fetal hemoglobin (FNRBC) and the mean picograms of fetal or adult hemoglobin per nucleated erythrocyte (picograms HbF/NRBC, picograms HbA/NRBC) were assayed in 14-d-old colonies (bursts) derived from peripheral blood erythroid progenitors. In the peripheral blood of 11 normal adults only 2.2+/-0.5% (mean+/-SE) erythrocytes contained HbF whereas pooled bursts from the same subjects revealed a 13-fold increase in the percentage of FNRBC (29.6+/-3.9%). In culture both the picograms HbF/NRBC (5.2+/-0.4) and the picograms HbA/NRBC (27.7+/-1.5) are increased approximately 20% above the mean in vivo levels in NRBC from normal bone marrow aspirates. Analysis of each of 58 bursts from one subject demonstrated that FNRBC are present in all bursts and range from 5.0 to 95.0% of the total NRBC per burst. The percent FNRBC in each burst was neither correlated with picograms HbF/NRBC per burst nor with picograms HbA/NRBC per burst. Individual subcolonies from one burst in each of two subjects demonstrated between 3 and 81% FNRBC. These findings indicate that first, the increase in HbF production in culture is primarily due to increased production of the number of cells containing HbF, not to increased picograms HbF/NRBC. Second, all 14-d bursts contain some FNRBC. Third, just as seen in vivo, the picograms HbF/cell and the number of cells that contain HbF are independently regulated in culture. Fourth, commitment to produce HbF in vitro continues after subcolony formation in 14-d-old bursts. Augmentation of HbF production in culture therefore closely resembles that seen in acute erythroid stimulation in vivo.

Adult↗
PubMed1995

Endogenous production of interleukin 15 by activated human monocytes is critical for optimal production of interferon-gamma by natural killer cells in vitro.

Natural killer (NK) cells are large granular lymphocytes that constitutively express functional IL-2 receptors. We have shown that recombinant human IL-15 uses the IL-2 receptor to activate human NK cells and can synergize with recombinant human IL-12 to stimulate NK cell production of IFN-gamma in vitro. IFN-gamma production by NK cells is critical in the prevention of overwhelming infection by obligate intracellular microbial pathogens in several experimental animal models. Herein, we demonstrate that human monocytes produce IL-15 protein within 5 h of activation with LPS. Using an IL-15-neutralizing antiserum in a coculture of LPS-activated monocytes and NK cells, we demonstrate that monocyte-derived IL-15 is critical for optimal NK cell production of IFN-gamma. Endogenous IL-15 activates NK cells through the IL-2 receptor, and with endogenous IL-12, regulates NK cell IFN-gamma after monocyte activation by LPS. These in vitro studies are the first to characterize a function for endogenous IL-15, and as such, suggest an important role for IL-15 during the innate immune response. IL-15 may be an important ligand for the NK cell IL-2 receptor in vivo.

Animals↗
PubMed1995

Volatile fatty acids, metabolic by-products of periodontopathic bacteria, inhibit lymphocyte proliferation and cytokine production.

Short-chain fatty acids are a major by-product of anaerobic metabolism and can be detected in gingival fluid from periodontal pockets. Since most T cells are present subjacent to the pocket epithelium in conjunction with the plasma cells, it is important to know how these T cells are affected by short-chain fatty acids produced by subgingival plaque. The purpose of this study is to examine the effects of extracellular metabolites from periodontopathic bacteria on the proliferation and cytokine production of mouse splenic cells as a potential mechanism of imbalance among host-microbial interactions. A low-molecular-weight, heat-stable agent present in the two-day culture filtrate of Porphyromonas gingivalis, Prevotella loescheii, and Fusobacterium nucleatum significantly depressed Con A- and LPS- induced cell proliferation. To determine whether short-chain fatty acids present in the filtrate could account for the depression, we tested extracted volatile and non-volatile fatty acids for their effects on mitogenic activity. The volatile fatty acids extracted from immunosuppressive supernatants greatly inhibited T- and B- cell proliferation. Among these volatile fatty acids, butyric, propionic, valeric, and isovaleric acids impaired cell proliferation dose-dependently. From gas-liquid chromatographic analysis data, it is suggested that immuno-inhibitory activities in culture filtrates are mainly attributable to butyric and isovaleric acids in P. gingivalis, to propionic, butyric, and isovaleric acids in P. loescheii, and to butyric acid in F. nucleatum. Furthermore, these fatty acids significantly depressed interleukin 2 (IL-2), IL-4, IL-5, IL-6, and IL-10 production by Con A-stimulated splenic-T cells dose-dependently.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2001

Variability in fricative production and spectra: implications for the hyper- and hypo- and quantal theories of speech production.

Fricative spectral data are compared with articulatory data from electropalatographic (EPG) recordings in an investigation of coarticulatory effects on the acoustic signal. Data were taken from CV tokens produced by four female speakers of Australian English. Results are presented for the coronal fricatives /theta s [symbol: see text] z [symbol: see text]/ in seven monophthong vowel contexts. The analysis consists of a comparison of spectral centre of gravity (COG) with EPG centre of gravity measured along the horizontal dimension. The correlation between the articulatory and the acoustic data is quite high. Overall, the sibilant fricatives show very little variability in production, while the nonsibilant dental shows a good deal of variability. This is reflected in the spectral output. It is also shown that the alveolar sibilants show more effect from vowel context than do the postalveolar sibilants. These results are interpreted as showing that coarticulatory resistance is indeed greater for sibilant fricatives, but that degree of tongue body raising inherent in the fricative's production must also be taken into account. The results for overall variability are discussed with reference to the Hyper- and Hypo- and Quantal Theories of speech production. It is suggested that sibilant fricatives do not lend themselves to the articulatory imprecision which, according to these theories, characterizes perceptually salient, and typologically common, speech sounds.

Adult↗
PubMed1988

Thyrotropin induces growth and iodothyronine production in a human thyroid cell line without affecting adenosine 3',5'-monophosphate production.

Using a recently described cell line derived from the fusion of human thyroid and human myeloma cells, we studied the effects of TSH on cell growth, iodide organification, and cAMP production. Although these cells grow in the absence of TSH, when incubated for 2 days in serum-free medium containing purified human or bovine TSH, there was a significant increase in cellular DNA content. The stimulatory effect was observed at concentrations as low as 0.5 microU/ml, which produced a significant increase in DNA content, and was maximal with 5 microU/ml. This effect was still present after 6 days of incubation. Electron microscopy performed by an unbiased observer on cells incubated in the presence of TSH showed an increase in the calculated size of the cells and the nucleus which was significant at 0.1 microU/ml and maximal at 1 microU/ml. Stimulation of 125I organification and hormone production was observed at TSH concentrations as low as 1 microU/ml and was maximal at 10 microU/ml. However, neither TSH (1-50 microU/ml) nor forskolin (10(-6) M) stimulated cAMP production. These data suggest that these cells lack a functional adenylate cyclase pathway and that growth and iodide organification are mediated by other second messenger systems. Such a cell line could yield new insights into the mechanisms of TSH action and may provide a sensitive bioassay for TSH and other thyrotropic factors.

Cell Division↗
PubMed2004

Rate of production of plasma and very-low-density lipoprotein (VLDL) apolipoprotein C-III is strongly related to the concentration and level of production of VLDL triglyceride in male subjects with different body weights and levels of insulin sensitivity.

Overweight individuals with reduced insulin sensitivity often have mild to moderate hypertriglyceridemia. To investigate the role of apolipoprotein (apo)C-III metabolism in the etiology of hypertriglyceridemia in these individuals, we investigated 10 male subjects with different body weights (body mass index, 24-34 kg/m(2)) and insulin sensitivity (homeostasis model assessment, 4.7-35.0). Total plasma and very-low-density lipoprotein (VLDL) apoC-III kinetics, as well as VLDL triglyceride (TG) and VLDL apoB kinetics, were measured with iv injected stable isotopes. The apoC-III, TG, and apoB levels in VLDL ranged from 2.9-18.2 mg/dl, 0.49-2.89 mmol/liter, and 6.7-29.3 mg/dl, respectively. Mean production rates (PRs) were: VLDL apoC-III, 20.2 +/- 4.1 micromol/d (range, 8.0-44.8); VLDL TG, 26.9 +/- 4.6 mmol/d (range, 10.2-51.1); and VLDL apoB, 4.4 +/- 0.8 micromol/d (range, 1.5-9.1). VLDL apoC-III PRs were significantly correlated with body mass index, homeostasis model assessment, and plasma TG (r = 0.66, P < 0.05; r = 0.80, P < 0.01; r = 0.95, P < 0.001, respectively). Similar correlations were found for plasma apoC-III PRs (r = 0.70, P < 0.05; r = 0.67, P < 0.05; r = 0.80, P < 0.01, respectively). Fractional catabolic rates (FCRs) were not significantly related to metabolic variables. VLDL TG levels were strongly related to VLDL apoC-III levels (r = 0.99, P < 0.001) and VLDL apoC-III PRs (r = 0.94, P < 0.001). VLDL apoC-III levels were more strongly correlated with VLDL TG PRs (r = 0.81, P < 0.01) than with VLDL TG FCRs or VLDL apoB FCRs (r = -0.53, P = 0.12; r = -0.37, P = 0.29). These results suggest that increased hepatic production of VLDL apoC-III is characteristic of subjects with higher body weights and lower levels of insulin sensitivity and is strongly related to the plasma concentration and level of production of VLDL TG.

Adult↗
PubMed1998

The daily cortisol production reinvestigated in healthy men. The serum and urinary cortisol production rates are not significantly different.

We have measured the urinary cortisol production rate (uCPR) simultaneously with the serum cortisol production rate (sCPR) in four healthy men within a period of 3 days. uCPR, determined by isotope dilution of 11-oxoetiocholanolone was compared with sCPR, which was measured in three different ways (a, b, c). Blood was sampled at 10-min intervals for 24 h, and deconvolution analysis was applied to the cortisol concentrations. The daily serum cortisol production per liter, multiplied by the distribution volume yielded sCPR. The measurement methods are characterized as follows: a) the secretion and elimination terms were free; b) like method a, but with the input of the rate constants alpha and beta into the elimination function; c) the average 24-h cortisol concentration was multiplied by the metabolic clearance rate. uCPR was 25.4 +/- 4.7 [range: 21.3-31.4] micromol/(m2 x day), sCPR (method a) was 28.8 +/- 4.5 [range: 23.5-34.3] micromol/(m2 x day), sCPR (method b) was 27.9 +/- 8.1 [range: 18.5-37.7] micromol/(m2 x day), and sCPR (method c) was 29.3 +/- 4.8 [range: 22.7-33.2] micromol/(m2 x day). uCPR did not significantly differ from each of the 3 sCPR values (P > 0.30; > 0.46; and > 0.06, respectively). The patterns of the cortisol secretory rates in the present and previous studies do not necessarily represent the physiological process of the secretory bursts. We conclude that the estimated CPR, being 25-30 micromol/(m2 x day) [9-11 mg/(m2 x day)], can serve as a guideline for glucocorticoid replacement dose and that the urinary route to measure CPR is preferred because of its relative ease.

Humans↗
PubMed2005

A series of crystal structures of a meta-cleavage product hydrolase from Pseudomonas fluorescens IP01 (CumD) complexed with various cleavage products.

Meta-cleavage product hydrolase (MCP-hydrolase) is one of the key enzymes in the microbial degradation of aromatic compounds. MCP-hydrolase produces 2-hydroxypenta-2,4-dienoate and various organic acids, according to the C6 substituent of the substrate. Comprehensive analysis of the substrate specificity of the MCP-hydrolase from Pseudomonas fluorescens IP01 (CumD) was carried out by determining the kinetic parameters for nine substrates and crystal structures complexed with eight cleavage products. CumD preferred substrates with long non-branched C6 substituents, but did not effectively hydrolyze a substrate with a phenyl group. Superimposition of the complex structures indicated that benzoate was bound in a significantly different direction than other aliphatic cleavage products. The directions of the bound organic acids appeared to be related with the k(cat) values of the corresponding substrates. The Ile139 and Trp143 residues on helix alpha4 appeared to cause steric hindrance with the aromatic ring of the substrate, which hampers base-catalyzed attack by water.

Crystallography, X-Ray↗
PubMed1999

Longevity, lifetime pig production and productivity, and age at first conception in a cohort of gilts observed over six years on commercial farms.

An observational cohort study was conducted using a producer group of 33 farms selected based on their completeness of reproduction data, including dates of birth, entry to a herd, and removal. Average lifetime pig production and parity at removal in a cohort of 2,265 females born in 1990 were 67.2 pigs born alive and 5.6 parities, respectively. Approximately 90% of farrowings occurred from the second through the fourth year from birth. Farrowing rates between parities of 2 and 4 were higher than other parities, and pigs born alive from parities 3 to 5 were the greatest among parities. The 10th and 90th percentiles of age at first conception were 227 and 322 days. Increasing the age at first mating was associated with low farrowing rate (P<0.01) in parity 0. Older age at first conception was associated with lower parity at removal, shorter reproductive herd life, and fewer lifetime pigs born alive (P< 0.01). Of the 2,265 breeding females, 253 (11.2%) were re-mated at parity 0 and farrowed. These sows with a record re-mating at parity 0 had lower parity at removal, less lifetime pig production and lower lifetime productivity than those with no re-mating at parity 0 (P<0.01). It is recommended that unbred gilts 230 days of age or older should be mated soon.

Age Factors↗
PubMed2004

High-productivity continuous biofilm reactor for butanol production: effect of acetate, butyrate, and corn steep liquor on bioreactor performance.

Corn steep liquor (CSL), a byproduct of the corn wet-milling process, was used in an immobilized cell continuous biofilm reactor to replace the expensive P2 medium ingredients. The use of CSL resulted in the production of 6.29 g/L of total acetone-butanol-ethanol (ABE) as compared with 6.86 g/L in a control experiment. These studies were performed at a dilution rate of 0.32 h-1. The productivities in the control and CSL experiment were 2.19 and 2.01 g/(L.h), respectively. Although the use of CSL resulted in a 10% decrease in productivity, it is viewed that its application would be economical compared to P2 medium. Hence, CSL may be used to replace the P2 medium. It was also demonstrated that inclusion of butyrate into the feed was beneficial to the butanol fermentation. A control experiment produced 4.77 g/L of total ABE, and the experiment with supplemented sodium butyrate produced 5.70 g/L of total ABE. The butanol concentration increased from 3.14 to 4.04 g/L. Inclusion of acetate in the feed medium of the immobilized cell biofilm reactor was not found to be beneficial for the ABE fermentation, as reported for the batch ABE fermentation.

Acetates↗
PubMed2000

Lipase production by Penicillium restrictum using solid waste of industrial babassu oil production as substrate.

Lipase, protease, and amylase production by Penicillium restrictum in solid-state fermentation was investigated. The basal medium was an industrial waste of babassu oil (Orbignya oleifera) production. It was enriched with peptone, olive oil, and Tween-80. The supplementation positively influenced both enzyme production and fungal growth. Media enriched with Tween-80 provided the highest protease activity (8.6 U/g), whereas those enriched with peptone and olive oil led to the highest lipase (27.8 U/g) and amylase (31.8 U/g) activities, respectively.

Amylases↗
PubMed2000

Improvements in titer, productivity, and yield using Solka-floc for cellulase production.

Researchers studying cellulase enzymes for the economical production of fuel ethanol envision cellulose as the carbon source. However, submerged Trichoderma reesei cultures grown on cellulose exhibit high run-to-run variability. Thus, an investigation of 30 batch cellulase production experiments was instrumental in determining fermentation conditions that improved enzyme titers, yields, and productivities. Eighteen of the 30 batch experiments experienced minimal process upsets and were classified into eight groups based on agitation rate, gas sparge rate, and the use of oxygen supplementation. Comparing corn steep liquor with yeast extract/peptone also tested the effect of different sources of nitrogen in the media. Average 7-d enzyme titers were doubled from 4 to 8 FPU/mL primarily by increasing aeration.

Biotechnology↗