SEARCH · PubMed Health

Results for “availability”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 901 records · Page 50Linked to original sources

PubMed2001

Plant density and nutrient availability constrain constitutive and wound-induced expression of trypsin inhibitors in Brassica napus.

We investigated the effects of plant density on plant size, leaf total soluble protein content, and constitutive and wound-induced levels of proteinaceous trypsin inhibitors in pot-grown Brassica napus seedlings in two greenhouse studies. We manipulated plant density by varying the number of intraspecific neighbors surrounding a target plant in the center of each pot. In general, constitutive and induced levels of trypsin inhibitors were significantly reduced by competition in a density-dependent manner, to the extent that induction was greatly reduced or abolished in target plants surrounded by six neighbors. To investigate whether the effects of plant density on inhibitor production were mediated by nutrient availability, we manipulated the concentration of a complete fertilizer applied to target plants surrounded by six neighbors in two greenhouse studies. In general, constitutive and wound-induced levels of inhibitors in plants surrounded by six neighbors were increased by nutrient addition in a dose-dependent manner, such that wound-induction was completely restored in competing plants under conditions of high nutrient availability. Leaf total soluble protein content, measured only in the second trial of each experiment, was not affected by any of the treatments. The effects of plant density, nutrient addition, and wounding on inhibitor levels in all experiments were independent of their effects on above-ground plant size at the time of wounding. Overall, our results suggest that decreasing nutrient availability mediates the density-dependent reductions in inhibitor levels in B. napus seedings.

Brassica napus↗

PubMed1998

Choline availability modulates the expression of TGFbeta1 and cytoskeletal proteins in the hippocampus of developing rat brain.

Choline availability influences long-term memory in concert with changes in the spatial organization and morphology of septal neurons, however little is known concerning the effects of choline on the hippocampus, a region of the brain also important for memory performance. Pregnant rats on gestational day 12 were fed a choline control (CT), choline supplemented (CS), or choline deficient (CD) diet for 6 days and fetal brain slices were prepared on embryonic day 18 (E18). The hippocampus in these brain slices was studied for the immunohistochemical localization of the growth-related proteins transforming growth factor beta type 1 (TGFbeta1) and GAP43, the cytoskeletal proteins vimentin and microtubule associated protein type 1 (MAP1), and the neuronal cell marker neuron specific enolase (NSE). In control hippocampus, there was weak expression of TGFbeta1 and vimentin proteins, but moderately intense expression of MAP1 protein. These proteins were not homogeneously distributed, but were preferentially localized to cells with large cell bodies located in the central (approximately CA1-CA3) region of the hippocampus, and to the filamentous processes of small cells in the fimbria region. Feeding a choline-supplemented diet decreased, whereas a choline-deficient diet increased the intensity of immunohistochemical labeling for these proteins in E18 hippocampus. GAP43 and NSE were localized to peripheral nervous tissue but not hippocampus, indicating that the maturation of axons and neurite outgrowth in embryonic hippocampus were unaffected by the availability of choline in the diet. These data suggest that the availability of choline affects the differentiation of specific regions of developing hippocampus.

Aging↗

PubMed2003

Individual and school level effects of perceived harm, perceived availability, and community size on marijuana use among 12th-grade students: a random effects model.

A hierarchical linear model was used to estimate the individual and school level effects for marijuana use among a national sample of 12th-grade students. School effects were small in comparison to individual level effects, accounting for 2.9% of the variance in marijuana use. At the individual level, perceived harm, perceived availability, and their interaction were significant predictors, each of which varied randomly across schools. Among two school-level predictors, the normative environment for perceived harm was not significant, but normative perceived availability predicted level of marijuana use. The effect of perceived availability on marijuana use was stronger in larger, compared to smaller communities. Results are discussed in light of the use of random regression methods for identifying school-specific patterns of risk and protection for prevention planning.

Adolescent↗

PubMed2004

Disentangling the effects of safety-behavior utilization and safety-behavior availability during exposure-based treatment: a placebo-controlled trial.

The primary aim of the current study was to further investigate the deleterious effects of safety-seeking behaviors on fear reduction by disentangling the effects of perceived availability of threat-relevant safety behaviors during treatment versus their actual use. Participants (N=72) displaying marked claustrophobic fear were randomly assigned to 1 of 5 conditions: (a) exposure only (EO), (b) exposure with phobic safety-behavior availability (SBA), (c) exposure with safety-behavior utilization (SBU), (d) credible placebo treatment (PL), or (e) wait list (WL). High end-state functioning rates at posttreatment were as follows: EO = 94%, SBA = 45%, SBU = 44%, PL = 25%, and WL = 0%. Findings suggest that it is the perception of the availability of safety aids as opposed to their actual use that exerts a disruptive effect on fear reduction. Clinical implications are discussed.

Adolescent↗

PubMed2006

Relation availability was not confounded with familiarity or plausibility in Gagné and Shoben (1997): Comment on Wisniewski and Murphy (2005).

C. L. Gagné and E. Shoben (1997) proposed that the conceptual system contains information about how concepts are used to modify other concepts and that this relational information influences the ease with which concepts combine. Recently, E. J. Wisniewski and G. L. Murphy suggested that C. L. Gagné and E. Shoben's measure of relation availability was confounded with familiarity and plausibility and that the participants could simply retrieve the stored meanings of the phrases because the phrases were not novel. In this article, the authors demonstrate that E. J. Wisniewski and G. L. Murphy's plausibility and familiarity judgments are dependent variables that (a) are themselves responsive to changes in relation availability, (b) modifier relation availability predicts response time even when the influence of phrase familiarity and plausibility is controlled, and (c) the materials consisted of mainly novel phrases.

Association Learning↗

PubMed2005

Quantifying precision and availability of location memory in everyday pictures and some implications for picture database design.

The authors investigated whether memory for object locations in pictures could be exploited to address known difficulties of designing query languages for picture databases. M. W. Lansdale's (1998) model of location memory was adapted to 4 experiments observing memory for everyday pictures. These experiments showed that location memory is quantified by 2 parameters: a probability that memory is available and a measure of its precision. Availability is determined by controlled attentional processes, whereas precision is mostly governed by picture composition beyond the viewer's control. Additionally, participants' confidence judgments were good predictors of availability but were insensitive to precision. This research suggests that databases using location memory are feasible. The implications of these findings for database design and for further research and development are discussed.

Female↗

PubMed1985

Influence of reduced oxygen availability on cerebral metabolic changes during bicuculline-induced seizures in rats.

The objective of the present work was to study cerebral energy metabolism at threshold levels of hypoxia, i.e., degrees of hypoxia that abolish cerebral electrical activity, in the "normal" and in the epileptic brain. Seizures were induced by intravenous bicuculline and cerebral oxygen availability was reduced by a combination of lowered PO2 and reduced blood pressure to give a transformation of the burst suppression pattern to either one with single spikes or overt EEG flattening. Nonepileptic control animals were exposed to degrees of hypoxia that gave either a markedly depressed EEG pattern with sparse slow waves or EEG flattening. Epileptic and nonepileptic groups proved comparable in terms of calculated oxygen availability and cerebral oxygen consumption at the threshold of "transmission failure." At levels of hypoxia that markedly attenuated or completely abolished seizure discharge, the cerebral metabolic changes were more marked than in comparable nonepileptic animals. These changes comprised an imminent severe perturbation of cerebral cortical phosphorylation potential, a pronounced lactic acidosis with a precipitous redox change, and a marked accumulation of ammonia. The more labile energy balance of the epileptic brain may indicate that the "seizure state" either increases cellular energy demands in spite of the electrical silence or reduces the efficiency of ATP production at the prevailing oxygen availability. It is conceivable that energy failure elicited by complicating hypoxia can aggravate or precipitate brain cell damage in epilepsy.

Animals↗

PubMed2002

Options available--from start to finish--for obtaining data from DNA microarrays II.

Microarray technology has undergone a rapid evolution. With widespread interest in large-scale genomic research, an abundance of equipment and reagents have now become available and affordable to a large cross section of the scientific community. As protocols become more refined, careful investigators are able to obtain good quality microarray data quickly. In most recent times, however, perhaps one of the biggest obstacles researchers face is not the manufacture and use of microarrays at the bench, but storage and analysis of the array data. This review discusses the most recent equipment, reagents and protocols available to the researcher, as well as describing data analysis and storage options available from the evolving field of microarray informatics.

DNA↗

PubMed2004

Is dietary fat intake related to liking or household availability of high- and low-fat foods?

OBJECTIVE: Despite the increasing availability of low- and reduced-fat foods, Americans continue to consume more fat than recommended, which may be a contributing factor to the obesity epidemic. This investigation examined relationships between liking and household availability of high- and low-fat foods and their association with dietary fat intake. RESEARCH METHODS AND PROCEDURES: A food frequency questionnaire assessed percent calories from fat consumed over the past year in 85 men and 80 women. Participants reported their degree of liking 22 "high-fat foods" (>45% calories from fat) and 22 "low-fat foods" (<18% calories from fat), and the number and percentage (number of high- or low-fat foods/total number of foods x 100) of these high- and low-fat foods in their homes. RESULTS: Hierarchical regression analyses examined the ability of liking and household availability of low- and high-fat foods to predict percent dietary fat intake. After controlling for age, sex, and BMI, liking ratings for high- and low-fat foods and the interaction of liking for low-fat foods by the percentage of low-fat foods in the household were significant predictors of percent dietary fat consumed. Greater liking of high-fat foods and lower liking of low-fat foods, both alone and combined with a lower percentage of low-fat foods in the home, were predictive of higher dietary fat intake. DISCUSSION: Interventions designed to reduce dietary fat intake should target both decreasing liking for high-fat foods and increasing liking for low-fat foods, along with increasing the proportion of low-fat foods in the household.

Adult↗

PubMed2006

Relationship of adiponectin with insulin sensitivity in humans, independent of lipid availability.

OBJECTIVE: To test in humans the hypothesis that part of the association of adiponectin with insulin sensitivity is independent of lipid availability. RESEARCH METHODS AND PROCEDURES: We studied relationships among plasma adiponectin, insulin sensitivity (by hyperinsulinemic-euglycemic clamp), total adiposity (by DXA), visceral adiposity (VAT; by magnetic resonance imaging), and indices of lipid available to muscle, including circulating and intramyocellular lipid (IMCL; by 1H-magnetic resonance spectroscopy). Our cohort included normal weight to obese men (n = 36). RESULTS: Plasma adiponectin was directly associated with insulin sensitivity and high-density lipoprotein-cholesterol and inversely with plasma triglycerides but not IMCL. These findings are consistent with adiponectin promoting lipid uptake and subsequent oxidation in muscle and inhibiting TG synthesis in the liver. In multiple regression models that also included visceral and total fat, free fatty acids, TGs, and IMCL, either alone or in combination, adiponectin independently predicted insulin sensitivity, consistent with some of its insulin-sensitizing effects being mediated through mechanisms other than modulation of lipid metabolism. Because VAT directly correlated with total fat and all three indices of local lipid availability, free fatty acids, and IMCL, an efficient regression model of insulin sensitivity (R2 = 0.69, p < 0.0001) contained only VAT (part R2 = 0.12, p < 0.002) and adiponectin (part R2 = 0.41, p < 0.0001) as independent variables. DISCUSSION: Given the broad range of total adiposity and body fat distribution in our cohort, we suggest that insulin sensitivity is robustly associated with adiponectin and VAT.

Adiponectin↗

PubMed1998

The A1 allele of the human D2 dopamine receptor gene predicts low D2 receptor availability in healthy volunteers.

Positron emission tomography (PET) studies have revealed significant interindividual variation in dopamine D2 receptor density in vivo in human striatum. Low D2 receptor binding in vivo has been found to associate with alcohol/substance dependence. It has been suggested that the A1 allele of human D2 receptor gene might be associated to a specific type of alcoholism and possibly to a reduced D2 receptor density in vitro. We have determined D2 dopamine receptor-binding density (Bmax), affinity (Kd) and availability (Bmax/Kd) in 54 healthy Finnish volunteers using PET and [11C]raclopride in order to determine whether the A1 allele is associated with a 'baseline' difference in D2 receptor characteristics in vivo. A statistically significant reduction in D2 receptor availability reflecting an alteration in receptor density was observed in the A1/A2 genotype group compared to the A2/A2 group. There was no difference in apparent Kd between the two groups. In conclusion, the association between the A1 allele and low D2 receptor availability in healthy subjects indicates that the A1 allele of the TaqIA polymorphism might be in linkage disequilibrium with a mutation in the promoter/regulatory gene element that affects dopamine D2 receptor expression. This study provides an in vivo neurobiological correlate to the A1 allele in healthy volunteers.

Adult↗

PubMed2000

Elevated hypothalamic/midbrain serotonin (monoamine) transporter availability in depressive drug-naive children and adolescents.

Cumulative data suggest depression in adulthood being connected to reduced availability of brain serotonin while the role of dopamine remains less specific. Prospective studies have shown a continuity of depressive episodes from childhood to adulthood, combined with poor social function and excess mortality. The object of this study was to examine whether alterations in brain serotonin and/or dopamine transporter levels are already present in depressive children and adolescents. We examined 41 drug-naive patients (aged 7-17) by single photon emission tomography (SPET) using iodine-123-labelled 23-carbomethoxy-3P3(iodophenyl) tropane [123I]beta-CIT as a tracer for monoamine transporters. In addition to the ordinary clinical examination, the patients were given a structured interview and information was gathered from teachers and parents with questionnaires. The diagnoses were established by consensus evaluation between three child psychiatrists. To test the serotonin hypothesis and the dopamine hypothesis regarding depression in children and adolescents, the series was divided into groups with depression present (31) and no depression present (10). In this study, the depressive child and adolescent patients had significantly higher serotonin transporter availability (P < 0.02) in the hypothalamic/midbrain area. Age did not correlate to the hypothalamic/midbrain serotonin transporter binding ratio. No significant difference in dopamine transporter availability in striatum was found between the depressive and the nondepressive children and adolescents.

Adolescent↗

PubMed2004

Serotonin and dopamine transporter availabilities correlate with the loudness dependence of auditory evoked potentials in patients with obsessive-compulsive disorder.

Brain monoaminergic function is involved in the pathophysiology of psychiatric disorders. The loudness dependence (LD) of the N1/P2 component of auditory evoked potentials has been proposed as a noninvasive indicator of central serotonergic function, whereas single photon emission computed tomography (SPECT) and [123I]beta-CIT can be used to visualize both serotonin (SERT) and dopamine transporters (DAT). The aim of the study was to correlate LD and SPECT measures in patients with obsessive-compulsive disorder, a condition with evidence for a serotonergic dysfunction. A total of 10 subjects received both neurophysiological and imaging investigations. Evoked potentials were recorded following the application of acoustic stimuli with increasing intensities. The LD of the relevant subcomponents (tangential dipoles) was investigated using dipole source analysis. SPECT was performed 20-24 h after injection of a mean 140 MBq [123I]beta-CIT. As a measure of brain SERT and DAT availabilities, a ratio of specific to nonspecific [123I]beta-CIT binding for the midbrain . pons region (SERT) and the striatum (DAT) was used. The LD of the right tangential dipole correlated significantly with both SERT and DAT availabilities (Pearson's correlations: rho = 0.69, p < 0.05, and rho = 0.80, p < 0.01, respectively). The correlations remained significant after controlling for the effects of age, gender, and severity of clinical symptoms. Associations between LD and both SERT and DAT availabilities further validate the use of neurophysiological approaches as noninvasive indirect measures of neurochemical brain function and point at a hypothesized interconnection of central monoaminergic systems.

Acoustic Stimulation↗

PubMed1983

Differences in polyamine availability and insertion into fibronectins released from normal and transformed cells.

1. Fibronectin released from transformed rat kidney cells compared with that released from normal rat kidney cells shows a 50% increase in amino group availability. 2. No such changes were observed in thiol and carboxy group availability or in sialic acid content. 3. The increased amino group availability is not due to a greater polyamine content, which was about 0.04 pmol/mg of protein. 4. Transglutaminase mediated the insertion of spermidine into normal cell fibronectin with linear kinetics. With fibronectin from transformed cells (temperature-sensitive mutant or wild-type), kinetics typical of substrate inhibition were observed. 5. Immunochemical analysis with an anti-polyamine antiserum and an anti-(human fibronectin) antiserum showed that fibronectins from normal and transformed cells react differently. The significance of these results is discussed in the light of changes in the secondary structure between the two fibronectins.

Animals↗

PubMed2002

Nitrate and phosphate availability and distribution have different effects on root system architecture of Arabidopsis.

Plant root systems can respond to nutrient availability and distribution by changing the three-dimensional deployment of their roots: their root system architecture (RSA). We have compared RSA in homogeneous and heterogeneous nitrate and phosphate supply in Arabidopsis. Changes in nitrate and phosphate availability were found to have contrasting effects on primary root length and lateral root density, but similar effects on lateral root length. Relative to shoot dry weight (DW), primary root length decreased with increasing nitrate availability, while it increased with increasing phosphate supply. Lateral root density remained constant across a range of nitrate supplies, but decreased with increasing phosphate supply. In contrast, lateral root elongation was suppressed both by high nitrate and high phosphate supplies. Local supplies of high nitrate or phosphate in a patch also had different effects. Primary root growth was not affected by a high nitrate patch, but growth through a high phosphate patch reduced primary root growth after the root left the patch. A high nitrate patch induced an increase in lateral root density in the patch, whereas lateral root density was unaffected by a high phosphate patch. However, both phosphate- and nitrate-rich patches induced lateral root elongation in the patch and suppressed it outside the patch. This co-ordinated response of lateral roots also occurs in soil-grown plants exposed to a nutrient-rich patch. The auxin-resistant mutants axrl, axr4 and aux1 all showed the wild-type lateral root elongation responses to a nitrate-rich patch, suggesting that auxin is not required for this response.

Arabidopsis↗

PubMedDate not supplied

Changes in hospital component therapy in response to reduced availability of whole blood.

The effects of a systematic reduction of whole blood (WB) availability on transfusion practice were studied at a large university-affiliated community hospital from 1978 through 1985. The reduction in WB availability was part of a planned statewide shift in blood procurement and processing from hospitals' individual blood banks to a new statewide blood center. Hospital WB use declined 96 percent, from 3400 to 109 units annually, with a net addition of more than 3000 units of plasma to the statewide stocks. A large increase in the use of other blood components occurred when WB was withdrawn, but this use fell sharply in 1984 and 1985, despite the continued relative unavailability of WB. Analysis of individual hospitals' services showed that increases in the use of packed red cells were distributed across all the services that frequently use red cell transfusions. However, a disproportionate rise and then fall in the use of fresh-frozen plasma and platelets for cardiovascular operations were observed. The data suggest that education and more conservative transfusion practices are reducing the use of blood components despite continued restricted availability of WB.

Blood Cells↗

PubMedDate not supplied

The effect of duration and time of food availability on the photoperiodic response in the male house sparrow, Passer domesticus.

We investigated the effects of food availability on the seasonal testicular growth in the photoperiodic house sparrow (Passer domesticus). Two experiments were performed, each lasting 4 weeks. In experiment 1, sparrows were exposed to natural (NDL; group 1), short (8L:16D; group 2) and long (16L:8D; groups 3-5) day lengths with access to food ad libitum (groups 1-3) or for 10 h (zeitgeber time (zt) 0-10, group 4; zt 0 is the time of light onset) or for 8 h (zt 8-16, group 5). Testes recrudesced under long, but not short and natural, day lengths, and the recrudescence under long days was influenced by the duration of food availability. In experiment 2, the sparrows were exposed to short (8L:16D, group 1) and long (16L:8D, groups 2-5) day lengths with access to food ad libitum (for groups 1 and 2) or for 6 h (for groups 3-5) at different times during the 16 h light period (group 3- zt 0-6, group 4- zt 5-11, group 5- zt 10-16). As the expected, the testes recrudesced only under long lengths, but the photoinduction was variable among the 4 groups. The testes grew to full size in groups 2 and 3 that received food either ad libitum or for 6 h at zt 0-6, but to sub-maximal size in the groups that received 6 h food either at zt 5-11 (group 4) or at zt 10-16 (group 5). Altogether, these results support the idea that the photoperiodic regulation of reproduction in a seasonally breeding species is influenced both by the duration and the time of food availability.

Analysis of Variance↗

PubMedDate not supplied

Safety and efficacy of currently available fibrin tissue adhesives.

PURPOSE: The purpose of this study is to review preparation methods, bonding power, preparation time, and costs associated with currently available autologous and homologous fibrin tissue adhesive preparations. METHODS: Two autologous fibrin tissue adhesive preparations (AFTA-A and AFTA-E), a single-donor homologous preparation, and 2 multiple-donor pooled homologous fibrin tissue adhesives, Vi-Guard and Tisseel, were evaluated and compared in relation to bonding power, preparation time, cost, bicompatibility, and biodegradability. RESULTS: Vi-Guard and Tisseel showed significantly greater bonding strengths than their single-donor counterparts. AFTA-C offers the quickest preparation time. All preparations were found to be similar in biocompatibility and biodegradability in soft tissue tests. Histology showed no infection or tissue reaction from adhesive exposure in any of the preparations. CONCLUSION: The optimal choice of a fibrin tissue adhesive is determined by the particular clinical indication. Currently available fibrin tissue adhesives vary appreciably in their bonding strength, cost, level of exposure risk, and preparation methods and times. Autologous preparations, which offer optimal safety, lack the strength and availability characteristics found with the multiple-donor preparations.

Absorbable Implants↗