Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “delta integration”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed1984

Effect of external abdominal irradiation on the dimensions and characteristics of the barriers to passive transport in the rat intestine.

Limited information is available on the effect of irradiation on the intestinal absorption of passively transported nutrients. In this study a previously validated in vitro technique was used to measure the uptake of fatty acids (FA), fatty alcohols and cholesterol into the jejunum, ileum and colon of control rats and animals exposed to cesium-137 source irradiation applied to the abdomen. The effective resistance of the intestinal unstirred water layer was measured with lauryl alcohol, and in control rats this resistance was lowest in the ileum, highest in the colon, and of intermediate value in the jejunum. Fourteen days after 600 rads, unstirred layer resistance was reduced by half in the colon when the bulk phase was stirred at 600 rpm, and in the jejunum, ileum and colon when the bulk phase was unstirred (0 rpm). The incremental change in the free energy of transfer (integral of delta Fw----l) was measured with a homologous series of saturated medium-chain length fatty acids; 14 days after 600 and 900 rads the value of integral of delta Fw----l in the jejunum rose significantly, and occurred when light and electron microscopic changes were minimal. Fourteen days after 300 rads, the uptake of FA 6:0-12:0 was reduced, but this decline in uptake appeared to be caused by a fall in the functional surface area of the membrane rather than a change in integral of delta Fw----l. The uptake of cholesterol into the jejunum, ileum and colon was unaffected by irradiation, suggesting that cholesterol and fatty acids may have different diffusion pathways through the membrane. Thus, external abdominal irradiation influences the dimensions and characteristics of the barriers to passive transport in the intestine of the rat, and thereby modifies the uptake of some but not all passively absorbed nutrients. These functional changes are not closely associated with morphological alterations.

Animals↗
PubMed1986

Tn5-mediated integration of the delta-endotoxin gene from Bacillus thuringiensis into the chromosome of root-colonizing pseudomonads.

Gene replacement mediated by Tn5 sequences was used to integrate the Bacillus thuringiensis subsp. kurstaki HD-1 delta-endotoxin gene (tox) into the chromosome of two corn root-colonizing strains of Pseudomonas fluorescens. A Tn5 transposase deletion element containing the tox gene (delta Tn5-tox) was substituted for a Tn5 element previously present in the P. fluorescens chromosome. Two classes of delta Tn5-tox elements were made. The first class encodes kanamycin resistance in addition to the Tox protein, whereas the second class encodes only the Tox protein. Both classes of delta Tn5-tox elements can no longer transpose, owing to a 324-base-pair deletion in the transposase gene of IS50R, minimizing the potential for horizontal gene transfer of the tox gene to other bacterial species. A frameshift mutation in the transposase gene of IS50L was also constructed to eliminate the possibility of suppression or of a spontaneous reversion at the ochre termination codon that would create an active transposase. Expression of the Tox protein in P. fluorescens strains 112-12 and Ps3732-3-7 was demonstrated by an immunological assay (Western blot) and toxicity against larvae of the tobacco hornworm (Manduca sexta).

Bacillus thuringiensis↗
PubMed1986

Early nutrition and intestinal transport function: effect of low-cholesterol diet.

Intestinal structure and function change with aging and with manipulation of the diet. The present study was undertaken to assess the absorption of selected nutrients and the morphologic characteristics of the intestine of weaning rabbits fed chow for 2, 4, or 6 weeks, and to determine the effect of feeding a low-cholesterol diet (LCD) for 2 weeks on these changes. Over the 6-week period in the chow-fed rabbits, an increase was seen in the jejunal villus height, villus surface area, and mucosal surface area, whereas in the ileum no change occurred in the villus height, and a decrease in the mucosal surface area was seen. Feeding LCD for 2 weeks had no effect on the jejunal or ileal mucosal surface area, and returning to chow for 2 weeks after 2 weeks of the low-cholesterol diet (LCD-C) also had no effect on mucosal surface area. Food consumption was lower in animals fed LCD than in animals fed chow, but body weight gain was unchanged. With an in vitro technique, the jejunal, ileal, and colonic uptake of lipids was shown to change over 6 weeks in animals fed chow, with a decline in the value of the incremental change in free energy (integral of delta Fw----I) associated with the uptake of medium-chain fatty acids, and an increase in the uptake of dodecanol, suggesting lower effective resistance of the intestinal unstirred water layer. The jejunal and ileal uptake of glucose and leucine fell from 2 to 6 weeks of age. Feeding LCD for 2 weeks was associated with marked changes in transport: in the jejunum there was increased uptake of fatty acids (FA) 6:0, 8:0, 12:0, 14:0, and 16:0, dodecanol, glucose, and galactose, and reduced uptake of FA 10:0 and 18:0, cholic acid, and leucine. Feeding LCD abolished the site-related differences in integral of delta FW----I, and reduced the early age-related fall in integral of delta FW----I in the ileum and colon. With LCD-C some of the changes in uptake were returned to normal, whereas for others new abnormalities became apparent. Thus, (1) the intestinal structure and transport function of young growing rabbits undergoes complex alterations, with the direction and magnitude of the absorption changes depending on the probe and the intestinal site; (2) feeding LCD for 2 weeks alters the age-related process of intestinal development.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗
PubMedDate not supplied

An integrating vector for tunable, high copy, stable integration into the dispersed Ty delta sites of Saccharomyces cerevisiae.

We have constructed a yeast integration vector targeted to chromosomal Ty delta sequences and used it to create Saccharomyces cerevisiae strains with stable tandem integrations ranging from 1 to 30 vector copies. The vector carries the bacterial NEO gene, allowing copy number to be tuned by varying G418 resistance, which generally increases with copy number as determined by quantitative Southern blot. Tandem integration into a single site is most commonly observed, but single-copy and two-site integration is also observed. Bovine pancreatic trypsin inhibitor was constitutively expressed and secreted using the NEO-based delta vector, and secretion levels were 2-10-fold improved relative to commonly used 2 mu multicopy yeast plasmids. The NEO-based Ty delta vector is a powerful tool for stable heterologous protein expression and secretion in yeast.

Animals↗
PubMed1984

Mechanisms of intestinal adaptation: unstirred layer resistance and membrane transport.

The effect of the resistance of unstirred water layers (UWL) on the kinetic parameters of active and passive intestinal transport processes is well established, but the possibility of adaptive changes in the resistance of this diffusion barrier in health and disease has only recently been appreciated. The rate of uptake (Jd) of a homologous series of saturated fatty alcohols into the jejunum is limited by diffusion through the UWL. The Jd of lauryl alcohol has been determined at different rates of stirring of the bulk phase, and at different sites along the intestine, in animals of different ages, in varying species, in rats with streptozotocin-induced diabetes mellitus, following abdominal irradiation, after acute and chronic exposure to ethanol, and after the feeding of various diets. The UWL varies in response to most of these experimental manipulations. After correcting for unstirred layer effects, the incremental change in free energy (integral of delta Fw----l) of the uptake of medium chain-length fatty acids and the maximal transport rate (Jmd) and Michaelis constant (Km) for glucose uptake were determined. These kinetic parameters changed in many of these experimental manipulations. However, there was no correlation between changes in UWL, integral of delta Fw----l, Jmd, Km or Jmd/Km. It is concluded that (1) the intestine is capable of adapting to a variety of physiological and pathological challenges; and (2) the major kinetic changes included UWL, integral of delta Fw----l, Jmd, and Km. The molecular mechanisms responsible for these changes in the dimensions and characteristics of the barriers to intestinal transport must now be defined.

Adaptation, Physiological↗
PubMed2006

Use of weakly coordinating anions to develop an integrated approach to the tuning of deltaE(1/2) values by medium effects.

An integrated approach to the control of deltaE(1/2) values, and therefore comproportionation equilibria, through medium effects was delineated for multi-step redox reactions involving cationic products. deltaE(1/2) values (defined as E(1/2)(2+/1+) - E(1/2)(1+/0)) of the two one-electron oxidations of bis(fulvalene)dinickel, 1, were measured under 45 different conditions of solvent and supporting electrolyte. The smallest value, 212 mV, was found in anisole/0.1 M [NBu4]Cl and the largest, 850 mV, in CH2Cl2/0.02 M Na[B(C6H3(CF3)2)4]. By systematically changing the solvent properties, the degree of ion-pairing strengths of the supporting electrolyte ions, and the concentration of the electrolytes, a set of ideal properties was found for maximizing deltaE(1/2) values involving positively charged electrode products. Most importantly (i) the solvent must be of lower polarity and low donor strength and (ii) the supporting electrolyte must have a weakly coordinating anion (WCA). The contrast in ion-pairing tendencies of 1(2+) with WCAs (on the weak side) and halides (on the strong side) mimics that of dianions in THF, where longer chain tetraalkylammonium ions (weak ion pairing) contrast with alkali metal ions (strong ion pairing). The broad picture of medium effects is that of a "mirror image" of solvent and electrolyte properties that influence the tuning of deltaE(1/2) values for multi-electron systems. Application was made both to the four-step oxidation process and to the two-step reduction process of the tetraferrocenyl complex Ni(S2C2Fc2)2, Fc = Fe(C5H5)(C5H4), 2. The two-electron process 2(0/2-) is observed either as a single two-electron voltammetric wave or as two well-separated one-electron waves, depending on the medium. The consequences of the present model for the interpretation of deltaE(1/2) values in mixed-valence chemistry are discussed.

Journal Article↗
PubMed1999

Moyamoya disease: evaluation with diffusion-weighted and perfusion echo-planar MR imaging.

PURPOSE: To determine the clinical efficacy of diffusion-weighted and perfusion echo-planar magnetic resonance (MR) imaging in the evaluation of moyamoya disease. MATERIALS AND METHODS: Seventeen patients with moyamoya disease were examined prospectively with diffusion-weighted and perfusion echo-planar MR imaging and conventional angiography. The change in the effective transverse relaxation rate (delta R2*) peak value, delta R2* peak time, and delta R2* integral were calculated to assess regional cerebral perfusion. The MR images were compared with angiographic images. RESULTS: Of the 34 posterior cerebral arteries (PCAs) of the 17 patients, 14 PCAs (41%) in 11 patients showed stenosis or occlusion. The delta R2* peak value ratio in the cerebral hemispheres decreased significantly, and the delta R2* peak time ratio increased significantly, with PCA stenosis and occlusion. However, no correlation was apparent between perfusion and extent of the stenotic or occlusive lesions of the internal carotid artery bifurcation. The frequency of cerebral infarctions was significantly increased in patients with stenotic or occlusive PCA lesions. For three acute infarctions, a decrease in the apparent diffusion coefficient was significantly correlated with a decrease in the delta R2* peak value, an increase in the delta R2* peak time, and a decrease in the delta R2* integral. CONCLUSION: Regional cerebral perfusion in moyamoya disease is decreased and delayed with PCA stenosis, with greater decrease and delay with PCA occlusion. Diffusion-weighted and perfusion imaging are useful for evaluating cerebral ischemia in moyamoya disease.

Adult↗
PubMed1986

Integration of the delta-endotoxin gene of Bacillus thuringiensis into the chromosome of root-colonizing strains of pseudomonads using Tn5.

The delta-endotoxin gene (tox) from Bacillus thuringiensis subsp. kurstaki HD-1 was cloned into Tn5 and the resulting Tn5-tox element transposed from a vector plasmid into the chromosome of six corn-root-colonizing strains of Pseudomonas fluorescens and Agrobacterium radiobacter. Chromosomal integration of the tox gene maximized stability and minimized the potential for horizontal transfer of the tox gene to other bacterial species. Expression of the tox gene was demonstrated by Western blot analysis and by toxicity against larvae of the tobacco hornworm (Manduca sexta). The method described illustrates how a given gene can be stably integrated into the chromosome of diverse bacterial species.

Bacillus thuringiensis↗
PubMed1987

IS50L as a non-self transposable vector used to integrate the Bacillus thuringiensis delta-endotoxin gene into the chromosome of root-colonizing pseudomonads.

Insertion sequence IS50L of transposon Tn5 was used as a non-self transposable vector to integrate the delta-endotoxin gene (tox) from Bacillus thuringiensis subsp. kurstaki HD-1 into the chromosome of two corn-root colonizing strains of Pseudomonas fluorescens (112-12 and Ps3732-3-7). A DNA fragment containing the KmR gene from Tn5 and tox was inserted into an IS50L element (IS50L-tox) contained on a suicide plasmid. Transposition of IS50L-tox into the chromosome of P. fluorescens 112-12 and Ps3732-3-7 occurred by selecting for KmR transconjugants and supplying transposase in cis from a linked IS50R element. A frameshift mutation in the transposase gene of the IS50L-tox element was also constructed to decrease the likelihood that suppression or a spontaneous reversion at the UAA (ochre) termination codon of IS50L would create an active transposase. The inability of IS50L-tox to transpose further minimizes the potential for horizontal gene transfer of the tox gene to other bacterial species. Expression of the Tox protein in strains 112-12 and Ps3732-3-7 was demonstrated by an immunological assay (Western blot) and toxicity against larvae of the tobacco hornworm (Manduca sexta).

Bacillus thuringiensis↗
PubMed1986

Progesterone and LH variations after LH-RH administration in the luteal phase of the menstrual cycle.

We have investigated the pituitary and luteal responses to LH-RH and their related changes. 11 normal women were studied during the luteal phase (day +4/+11). Blood samples were collected every 15 min for a basal period of 180 and 120 min after the intravenous administration of 25 micrograms of LH-RH. Progesterone (P) and LH were assayed by radioimmunoassay. Data were analyzed as maximum peak and its percent increase (delta max), integrated secretory area (ISA) and percent increase of ISA (delta A) in respect to basal values for both P and LH. LH-RH elicited a secretory response of both hormones in all cases. ISA of LH was significantly greater after LH-RH administration in respect to basal values (p less than 0.001) and delta max accounted to 475 +/- (SE) 36% of the basal concentration. Luteal responsiveness varied from about 115-130% to more marked increments. ISA of P differed from basal to stimulated conditions (p less than 0.05) and delta max was 166 +/- (SE) 14%. The analysis of temporal relationship between P and LH secretion showed that LH promptly rose after LH-RH, while the enhancement of P plasma levels occurred within 31 +/- 19 min after LH rise. Then P levels reached a plateau, values of which were statistically different from those observed before LH-RH administration. In two cases where luteal function was blunted or absent, in spite of marked increments of LH, P secretion did not occur. These data are consistent with the presence of close relationships between hypothalamic, pituitary and luteal functions and strengthen the contention about the usefulness of LH-RH during luteal phase for the lifespan and maintenance of corpus luteum.

Adult↗
PubMed1990

Integration host factor increases the transpositional immunity conferred by gamma delta ends.

The ends of the bacterial transposon gamma delta contain adjacent binding sites for gamma delta transposase and integration host factor (IHF). IHF+ and IHF- strains were used in conjunction with gamma delta transposon ends containing or lacking the site for IHF binding to determine the role that IHF plays in various gamma delta-mediated transposition events. IHF was not essential for the transposition of gamma delta and seemed to decrease its frequency of transposition about threefold. IHF played no role in determining the distribution of gamma delta inserts into a target replicon, nor did it significantly alter the frequency of simple transpositions. The only clear role discerned for IHF and the terminal IHF-binding sites was in transposition immunity. IHF stimulated the immunity of those plasmids that contain an end of gamma delta, provided the end included the terminal IHF-binding site. For both ends, the degree of stimulation of immunity was similar to the stimulation of binding of transposase by IHF.

Bacterial Proteins↗
PubMed2005

Delta and spindle components in the integrated EEG during nocturnal sleep for infants with developmental disabilities.

The delta and spindle components in the integrated EEG for 121 infants with developmental disabilities (from 4 mo. to 6 yr. of age: M=1.79, SD=0.14; 57 girls and 64 boys) were studied throughout nocturnal sleep. In 80 (66.1%, Group A) of 121 subjects, periodic changes of delta and spindle rhythm powers were noted in measurements of EEG made during sleep. In 28 (23.1%, Group B), delta but not spindle rhythm powers were found, and in the remaining 13 subjects (10.7%, Group C) neither delta nor spindle rhythm powers were found throughout measurements of EEG made during sleep. The Tsumori-Inage Questionnaire for Infants was administered to the parents to estimate subjects' behavioral developmental level as Developmental Quotients. Significantly lower mean Developmental Quotients were found for Groups B and C than Group A. These findings suggested that the presence or absence of delta and spindle rhythm powers in EEG measurements made during nocturnal sleep could be taken as an index of the severity of developmental disorders in infants with developmental disabilities.

Child↗
PubMed1996

Noncompetitive NMDA channel blockade during waking intensely stimulates NREM delta.

We previously found that subanesthetic doses of ketamine administered during the dark (active) period (DP) in rats strongly increased the integrated amplitude of the delta (1-4 Hz) electroencephalogram (EEG) in subsequent nonrapid eye movement (NREM) sleep. Here, we injected MK-801 into adult male Sprague-Dawley rats to test the hypothesis that such delta stimulation is characteristic of drugs that noncompetitively block the cation channel gated by the N-methyl-D-aspartate (NMDA) receptor. Injections of 0.3 and 0.5 mg/kg MK-801 in the middle of the DP produced waking intoxication for approximately 3 hr. In the following light period, NREM delta integrated amplitude was markedly increased in every rat (mean 55% increase after 0.5 mg/kg). A separate control experiment with 3-hr sleep deprivation in the mid-DP showed that the delta stimulation could not be attributed to sleep loss during MK-801 intoxication. Mechanisms by which NMDA cation channel blockade might stimulate NREM delta include a compensatory (homeostatic) sleep response to the metabolic, receptor or other neuronal effects of cation channel blockade; pathologic EEG slowing caused by neurotoxicity (in which case NREM delta might provide a noninvasive index of neurotoxic vacuolization); or a persistent, direct action of the drug or its metabolites on delta-generating systems. Questions of mechanism gain interest because of the magnitude of these pharmacologic effects on the sleep EEG component (delta) thought to be correlated with brain recuperative processes. In addition, our findings add to growing evidence implicating excitatory amino acid systems in sleep regulation.

Animals↗
PubMed1985

[Variants of the plasmid pAS8 delta with increased frequency of integration into Rhodopseudomonas sphaeroides chromosome--the result of IS8-element duplication].

The possible participation of IS8 and IS elements of Rhodopseudomonas sphaeroides in cointegrate formation by chromosome of the purple bacterium and plasmid pAS8-121 delta has been studied. The plasmid derivatives having deleted Tn7 have been studied. Plasmid integration into the chromosome of the purple bacterium is shown to be mediated by IS8 element of the plasmid. Plasmid derivatives having the integration potential increased for two orders were isolated by a series of intergeneric conjugational crosses during which plasmid pAS8-121 delta was transferred from Rhodopseudomonas sphaeroides (cointegrate of plasmid and chromosome) to Escherichia coli (plasmid in an autonomous state) and back to Rhodopseudomonas sphaeroides. The restriction analysis of plasmid DNA digested by Hpal and Smal restriction endonucleases has revealed the tandem duplications of IS8 in plasmids capable of integration into the chromosome of the purple bacterium with a high frequency.

Chromosomes, Bacterial↗
PubMed2000

Analytic environment-dependent tight-binding bond integrals: application to MoSi2.

We present the first derivation of explicit analytic expressions for the environmental dependence of the sigma, pi, and delta bond integrals within the orthogonal two-center tight-binding approximation by using the recently developed bond-order potential theory to invert the nonorthogonality matrix. We illustrate the power of this new formalism by showing that it not only captures the transferability of the bond integrals between elemental bcc Mo and Si and binary C11(b) MoSi2 but also predicts the absence of any discontinuity between first and second nearest neighbors for the ddsigma bond integral even though large discontinuities exist for ppsigma, pppi, and ddpi.

Journal Article↗
PubMed1987

Distribution of effective field in the ising spin glass of the +/- J model at T = O. Solutions as superpositions of delta-functions.

The integral equation for the distribution function of effective field of the +/- J random Ising model in the pair (Bethe) approximation is investigated. Its exact solutions at H (magnetic field) = O, T (temperature) = O and for z (coordination number) = 3 expressed as superpositions of 2N + 1 (more than 3), delta functions are considered. Then the integral equation is reduced to a system of algebraic equations of z - 1th degree with N + 1 unknowns. The system of the equations is solved by the Gröbner basis method with N = 1,2,3,4. The number of physically acceptable solutions for a given N is omega(N) + 1, where omega(N) is the number of divisors of N. The ground-state energy and entropy for these are calculated. They are very close in value (entropies are positive), and it is suggested that a number of physically acceptable solutions correspond to local stationary spin-glass states, as discussed in the literatures.

Chemical Phenomena↗
PubMed1997

Unmarked gene integration into the chromosome of Mycobacterium smegmatis via precise replacement of the pyrF gene.

After integration into the bacterial chromosome an exogenous gene may be stably expressed without continued selection for the recombinant locus. However, chromosomal integration events occur infrequently, requiring the concomitant integration of a drug resistance marker in order to identify colonies of recombinant cells. The generation of a drug-resistant recombinant strain can both reduce the in vivo applicability of the strain and preclude the use of recombinant vectors which use the same drug resistance marker. We have constructed a plasmid, pINT-delta, which allows recombination of exogenous genes onto the Mycobacterium smegmatis chromosome. The exogenous gene completely replaces the pyrF gene and the resultant strain lacks any exogenous drug resistance marker. The methodologies described herein are general and applicable even to those bacteria for which extrachromosomal plasmids are not available. Using pINT-delta we integrated the lacZ gene into the M. smegmatis chromosome via a precise exchange of lacZ and pyrF. The resultant strain was used to demonstrate that the expression of genes integrated at the pyrF locus is repressed twofold by inclusion of uracil in the growth medium. In addition, we used pINT-delta to construct an M. smegmatis strain with a precise deletion of its pyrF locus. This strain, TSm-627, grows normally in rich medium but does not grow in medium lacking uracil. TSm-627 cells allow the pyrF gene to be used as a selectable marker for growth on medium lacking uracil. In TSm-627 cells, the pyrF gene is also useful as a counterselectable marker on complete medium containing 5'-fluoroorotic acid and uracil. Two pyrF-containing plasmids, designed to exploit the new delta pyrF strain, have been constructed and their possible applications to problems in mycobacteriology are discussed.

Amino Acid Sequence↗
PubMed2005

Variation in carbon isotope discrimination in relation to plant performance in a natural population of Cryptantha flava.

Few studies of phenotypic selection have focused on physiological traits, especially in natural populations. The adaptive significance of plant water-use efficiency, the ratio of photosynthesis to water loss through transpiration, has rarely been examined. In this study, carbon isotopic discrimination, Delta, an integrated measure of water-use efficiency, was repeatedly measured in juveniles and adults in a natural population of the herbaceous desert perennial Cryptantha flava over a 4-year period and examined for plasticity in Delta, consistency between years in values of Delta, and evidence for selection on Delta phenotypes. There was significant concordance in Delta values among the 4 years for adult plants and significant correlations in Delta values measured in different years for juveniles and adults combined. The wettest year of the study, 1998, proved an exception because Delta values that year were not correlated with Delta values in any other year of the study. Consistency in Delta measured on the same plants in different years could indicate genotypic variation and/or consistency in the water status of the microhabitats the plants occupied. Two forms of plasticity in Delta were also evident; mean seasonal values were correlated with precipitation the preceding autumn, and Delta values also declined with plant size, indicating increasing water-use efficiency. Phenotypic selection was evident because in the first year of the study juvenile plants that would survive until year five averaged lower Delta values than did those that failed to survive. During the driest year, 2000, Delta was significantly negatively correlated with adult plant size, measured as the number of leaf rosettes, but the negative relationship between Delta and the number of flowering stalks, a more direct measure of fitness, was not significant. These results suggest that the direction of phenotypic selection on Delta changes as plants grow.

Boraginaceae↗