SEARCH · PubMed Health

Results for “Environment, Controlled”

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 829 records · Page 46Linked to original sources

PubMed1990

Response of abscisic acid in soybean leaves to NO2 exposure.

Soybean (Glycine max L. Merril) cv. 'Williams' plants were exposed 0.0, 0.05, 0.2 and 0.4 microl litre(-1) NO(2) under controlled environment. Amount of abscisic acid (ABA) was measured after either 7 h or 5 days of exposure as well as after 18 h of recovery period. For quantitative analysis of ABA enzyme-linked immunosorbent assay was used. A significant increase (160%) was observed in plants treated with 0.4 microl litre(-1) NO(2) for 5 days compared to an increase of only 82% on exposure for 7 h. Rate of recovery for plants treated with low doses of NO(2) was higher than those treated with higher doses.

Journal Article↗

PubMed1991

Origin of Bel-W3, Bel-C and Bel-B tobacco varieties and their use as indicators of ozone.

Since 1962, the tobacco variety Bel-W3 (Nicotiana tabacum L.), has been used in many countries as an indicator of the presence of phytotoxic concentrations of O(3). It is super-sensitive to O(3) and may produce easily recognizable symptoms for several weeks on the new, fully expanded leaves. Bel-B and Bel-C, tolerant and sensitive to O(3), respectively, are sometimes used along with Bel-W3. Information is provided on the origin and nature of these varieties. This includes their use as indicators of elevated O(3) concentrations, strength and limitations, and the inheritance and nature of resistance to O(3) in Bel-B. The varieties were the product of research initiated in 1957 to determine the cause and to reduce losses from tobacco weather fleck. Bel-C and Bel-B display the classical upper leaf surface injury; whereas, Bel-W3 develops primarily bifacial lesions. Data are provided to show differences in the amounts of acute and chronic injury on each variety when exposed to different O(3) exposure doses in controlled environments and under field conditions. There is discussion of the influence of environmental factors on response to O(3) by the varieties and the possibility of synergistic action of O(3) and SO(3) when tobacco is exposed to mixtures of these gases. The methods and results obtained with Bel-W3 in the Dutch National Monitoring Network for Air Pollution are presented in detail. Use of Bel-W3 world-wide as an indicator of elevated O(3) concentrations has been a significant factor in increasing the awareness of O(3) as a pollutant.

Journal Article↗

PubMed1987

Utilization of potatoes in bioregenerative life support systems.

Data on the tuberization, harvest index, and morphology of 2 cvs of white potato (Solanum tuberosum L.) grown at 12, 16, 20, 24 and 28 degrees C, 250, 400 and 550 micromoles s-1 m-2 photosynthetic photon flux (PPF), 350, 1000 and 1600 microliters l-1 CO2 will be presented. A productivity of 21.9 g m-2 day-1 of edible tubers from a solid stand of potatoes grown for 15 weeks with continuous irradiation at 400 micromoles s-1 m-2, 16 degrees C and 1000 microliters l-1 CO2 has been obtained. This equates to an area of 34.3 m2 being required to provide 2800 kcal of potatoes per day for a human diet. Separated plants receiving side lighting have produced 32.8 g m-2 day-1 which equates to an area of 23.6 m2 to provide 2800 kcal. Studies with side lighting indicate that productivities in this range should be realized from potatoes. Glycoalkaloid levels in tubers of controlled-environment-grown plants are within the range of levels found in tubers of field grown plants. The use and limitation of recirculating solution cultures for potato growth is discussed.

Carbon Dioxide↗

PubMed1992

Growing root, tuber and nut crops hydroponically for CELSS.

Among the crops selected by the National Aeronautics and Space Administration for growth in controlled ecological life support systems are four that have subsurface edible parts -- potatoes, sweet potatoes, sugar beets and peanuts. These crops have been produced in open and closed (recirculating), solid media and liquid, hydroponic systems. Fluorescent , fluorescent plus incandescent and high pressure sodium plus metal halide lamps have proven to be effective light sources. Continuous light with 16 degrees C and 28/22 degrees C (day/night) temperatures have produced highest yields for potato and sweet potato, respectively. Dry weight yields of up to 4685, 2541, 1151 and 207 g m-2 for for potatoes, sweet potatoes, sugar beets and peanuts, respectively, have been produced in controlled environment hydroponic systems.

Arachis↗

PubMed1994

Machine vision monitoring of plant health.

Techniques and algorithms to detect and diagnose disorders in plants grown in a controlled environment have been developed. A video camera senses features of plants which are indicative of disorders. Images are calibrated for size and color variations by using calibration templates. Different image segmentation techniques for separating object from background, have been implemented. Plant size and color properties have been investigated, temporal, spectral and spatial variation of leaves were extracted from the segmented images. Neural network and statistical classifiers were used to determine plant condition.

Algorithms↗

PubMed1996

Carbon dioxide exchange of lettuce plants under hypobaric conditions.

Growth of plants in a Controlled Ecological Life Support System (CELSS) may involve the use of hypobaric pressures enabling lower mass requirements for atmospheres and possible enhancement of crop productivity. A controlled environment plant growth chamber with hypobaric capability designed and built at Ames Research Center was used to determine if reduced pressures influence the rates of photosynthesis (Ps) and dark respiration (DR) of hydroponically grown lettuce plants. The chamber, referred to as a plant volatiles chamber (PVC), has a growing area of about 0.2 m2, a total gas volume of about 0.7 m3, and a leak rate at 50 kPa of <0.1%/day. When the pressure in the chamber was reduced from ambient to 51 kPa, the rate of net Ps increased by 25% and the rate of DR decreased by 40%. The rate of Ps increased linearly with decreasing pressure. There was a greater effect of reduced pressure at 41 Pa CO2 than at 81 Pa CO2. This is consistent with reports showing greater inhibition of photorespiration (Pr) in reduced O2 at low CO2 concentrations. When the partial pressure of O2 was held constant but the total pressure was varied between 51 and 101 kPa, the rate of CO2 uptake was nearly constant, suggesting that low pressure enhancement of Ps may be mainly attributable to lowered partial pressure of O2 and the accompanying reduction in Pr. The effects of lowered partial pressure of O2 on Ps and DR could result in substantial increases in the rates of biomass production, enabling rapid throughput of crops or allowing flexibility in the use of mass and energy resources for a CELSS.

Air Pressure↗

PubMed1989

Neuritic outgrowth in primary cell culture of neurons from the squid, Loligo pealei.

Giant fiber lobe (GFL) cells obtained from healthy squid reliably produced neuritic processes in culture. The processes were of two types, a sheet-like veil or thin branching neurites. The latter type was often associated with bulbous expansions (presumptive growth cones), at the termini, at branch points, or at sites of apparent contact among branches from two different cells. On poly-L-lysine substrate, veiling usually occurred by the fourth or fifth day in culture, while the branching processes appeared by one week to ten days. The elaboration of the outgrowths by the GFL neurons was influenced by the culture substrate and incubation temperature. The development of a preparation in which isolated GFL somata extend neurites in an easily controlled environment will permit the detailed study of axon fusion, channel expression and turnover, and synapse formation in the neurons.

Animals↗

PubMed1989

Effects of incandescent radiation on photosynthesis, growth rate and yield of 'Waldmann's Green' leaf lettuce.

Effects of different ratios incandescent (ln) to fluorescent (Fl) radiation were tested on growth of 'Waldmann's Green' leaf lettuce (Lactuca sativa L.) in a controlled environment. After 4 days of treatment, dry weight, leaf area, relative growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR) and photosynthetic rate (Pn) were greater for plants grown at 84 rather than 16% of total irradiance (82 W m-2) from ln lamps. Although leaf dry weight and area were 12-17% greater at 84% ln after the first 8 days of treatment, there were no differences in RGR or Pn between treatments during the last 4 days. If 84% ln was compared with 50% ln, all cumulative growth parameters, RGR, NAR and Pn were greater for 84% ln during the first 4 days of treatment. However, during the second 4 days, RGR was greater for the 50% ln treatment, resulting in no net difference in leaf dry weight or area between treatments. Shifting from 84 to 50% ln radiation between the first and second 4 days of treatment increased plant dry weight, leaf area, RGR and NAR relative to those under 84% ln for 8 days continuously.

Biomass↗

PubMed1995

Cultured hepatocytes as investigational models for hepatic toxicity: practical applications in drug discovery and development.

Drugs can fail at any phase during discovery, preclinical or clinical development due to unacceptable levels of toxicity, and liver is commonly the principle target organ. Investigational toxicology methods, using appropriate models and hypotheses, can often resolve problems, identify toxic chemical substituents and salvage therapeutic discovery programs. While in vivo models are used to investigate hepatic drug effects in the context of toxicokinetics and systemic influences, cell culture models provide in vitro systems for investigating specific mechanisms in a precisely controlled environment. Using primary hepatocytes isolated from laboratory animals, we have explored several drug-induced hepatic disorders that surfaced during different phases of drug discovery and development. Additionally, the use of human hepatocytes has allowed us to address concerns for human exposure, examine human relevance of animal data, and provide perspective on problems encountered in clinical trials.

Animals↗

PubMed1986

Esophageal obturator airway, ET tube, and pharyngeal-tracheal lumen airway.

Prior to approval of the EOA, this device had not been documented to be effective in oxygenation and ventilation in the pre-hospital arena. The studies quoted to demonstrate its usefulness were done in the very controlled environment of the operating room or of the emergency department. Indeed, the studies on blood gases obtained immediately upon entry into the emergency department would indicate that the esophageal obturator airway is an inadequate and ineffectual pre-hospital airway. The ability of the device to obstruct the esophagus, has been questioned. In a recent review of the EOA, Smith et al state that "How the EOA gained widespread popularity for use in patients requiring CPR without any evidence of its effectiveness is worthy of investigation". The Food and Drug Administration "grandfathered" the EOA as an acceptable device. This approval was to be reviewed with time, and if complications were reported, a second evaluation of the esophageal obturator airway was to be undertaken. Unfortunately, this has never occurred. We are now faced with the pharyngeal-tracheal lumen airway, which is being marketed for use in the pre-hospital area. The Food and Drug Administration approved the marketing and use of this device based on its similarity to the esophageal obturator airway. The PTL, is a device in many respects similar to the EOA. It has been tested in the operating room and the emergency department. In a study done on unsuccessfully resuscitated patients, it was as effective as an ETT. However, no study has shown that the PTL can be used successfully in the pre-hospital setting by ambulance personnel.(ABSTRACT TRUNCATED AT 250 WORDS)

Emergencies↗

PubMed1987

Effect of exogenous prolactin administration on lactational performance of dairy cows.

Eight Holstein cows were utilized to examine the effect of prolactin on lactational performance prior to peak milk production (day 21-34 postpartum) and after peak milk production (day 60-73 postpartum). During each 14 day period, cows received daily intramuscular injections of pituitary-derived bovine prolactin (120 mg; 13.0 IU/mg protein) or excipient. Cows were housed in a controlled environment at 18.1C, 47.8% relative humidity and a 15 hr light: 9 hr dark cycle. In cows administered exogenous prolactin, circulating prolactin concentrations increased within one-half hr post injection, peaked within 2 to 6 hours and declined through the remainder of the day. Average prolactin concentration in the plasma was increased 2 to 5 fold over the 24 hr period in response to prolactin treatment. Yields of milk and milk components (fat, lactose and protein) were not affected by prolactin treatment in either period but the concentration of alpha-lactalbumin in milk was significantly increased (P less than .10) in both periods. Circulating concentrations of somatotropin, triiodothyronine, thyroxine, glucagon, nonesterified fatty acids and glucose were not altered. In prolactin-treated cows, the milking-stimulated prolactin release was decreased at both the PM milking, when circulating concentrations of prolactin were high, and the AM milking, when prolactin concentrations had returned to baseline. Concentration of prolactin in milk tended to increase but was not significantly altered by administration of exogenous prolactin. However, prolactin concentrations in plasma were correlated (r = .56) with milk concentrations. It is clear that postpartum administration of exogenous prolactin during the period of lactation prior to peak milk yield or after peak milk yield does not alter lactational performance in high producing dairy cows.

Animals↗

PubMed2006

The influence of swelling and matrix degradation on the microstructural integrity of tendon.

Tendon is multi-level fibre composite material, responsible for the transmission of forces from muscles to the skeleton. It is composed of a hierarchical arrangement of collagenous units surrounded by a proteoglycan-rich matrix, arranged to support strain transfer, and thus contribute to the mechanical behaviour of tendon. This study examines the effect of swelling and enzymatic degradation on structural integrity at different levels of the tendon hierarchy. Biochemical and microstructural analysis are used to examine the effects of incubation on the composition and swelling of the matrix, prior to a mechanical characterisation of sample integrity. Results indicated significant swelling of tendon fibrils and interfibrillar matrix after incubation in phosphate buffered saline, leading to a reduction in ultimate tensile load, with failure initiated between fibrils and sub-fibrils. In contrast, incubation with the enzyme chondroitinase ABC resulted in a total removal of glycosaminoglycan from the samples, and a subsequent reduction in the extent of swelling. These fascicles also demonstrated an increase in failure loads, with failure predominating between fibres. The findings from this work confirm the importance of the non-collagenous matrix components in controlling strain transfer within tendon structures. It also highlights the necessity to maintain samples within a suitable and controlled environment prior to testing.

Animals↗

PubMed2005

Errors in transfusion medicine.

In the past two decades, health services in the developed world have directed much resource toward improving the safety of the blood supply. Blood is collected, tested, and processed within a carefully controlled environment, and quality is assured by rigorous donor selection procedures and increasingly sensitive and sophisticated testing for transfusion-transmitted pathogens. Additional safety strategies implemented by some blood services include leukocyte reduction, bacterial screening, and pathogen inactivation. Thus, the transfusion chain from the donor to the point of issue from the blood center is highly regulated and secure, and transfusion-transmitted infection is an increasingly rare event.

Blood Specimen Collection↗

PubMed2005

Patterning cells in highly deformable microstructures: effect of plastic deformation of substrate on cellular phenotype and gene expression.

We describe the fabrication of deformable microstructures by low-pressure-soft-microembossing (muSEmb) that provides in vitro experimental "test-beds" to investigate the interplay of mechanical and chemical stimuli on cell behavior in a highly controlled environment. Soft microembossing exploits the softness and plasticity of parafilm to fabricate microstructures by pressing a silicon master or an elastomeric poly(dimethylsiloxane) stamp into the parafilm. We demonstrate that a protein-resistant comb polymer can be printed into the raised features of the embossed microstructures, which imparts protein, and hence cell resistance to those regions of the microstructures. These two features of our fabrication methodology-microembossing followed by spatially selective transfer of a nonfouling polymer-forms the core of our strategy to pattern cells within the parafilm microstructures, such that the cells are confined within bottoms of the microstructures. Cell culture experiments demonstrated the preferential cell attachment of NIH 3T3 fibroblasts to the fibronectin (FN) micropatterns by immunofluorescence microscopy. The actin cytoskeleton realigned along the axis of applied mechanical stress, and stretched cells showed altered gene expression of cytoskeletal and matrix proteins in response to mechanical deformation. The use of parafilm as a substrate and muSEmb as a fabrication method provides a simple and widely accessible methodology to investigate cellular behavior under well-defined conditions of plastic deformation and surface ligand density.

Animals↗

PubMed2005

Rodent models of attention-deficit/hyperactivity disorder.

An ideal animal model should be similar to the disorder it models in terms of etiology, biochemistry, symptomatology, and treatment. Animal models provide several advantages over clinical research: simpler nervous systems, easily interpreted behaviors, genetic homogeneity, easily controlled environment, and a greater variety of interventions. Attention-deficit/hyperactivity disorder (ADHD) is a neurobehavioral disorder of childhood onset that is characterized by inattentiveness, hyperactivity, and impulsiveness. Its diagnosis is behaviorally based; therefore, the validation of an ADHD model must be based in behavior. An ADHD model must mimic the fundamental behavioral characteristics of ADHD (face validity), conform to a theoretical rationale for ADHD (construct validity), and predict aspects of ADHD behavior, genetics, and neurobiology previously uncharted in clinical settings (predictive validity). Spontaneously hypertensive rats (SHR) fulfill many of the validation criteria and compare well with clinical cases of ADHD. Poor performers in the five-choice serial reaction time task and Naples high-excitability rats (NHE) are useful models for attention-deficit disorder. Other animal models either focus on the less important symptom of hyperactivity and might be of limited value in ADHD research or are produced in ways that would not lead to a clinical diagnosis of ADHD in humans, even if ADHD-like behavior is displayed.

Animals↗

PubMed2005

Anaerobic and complementary treatment of domestic sewage in regions with hot climates--a review.

This study presents a literature review on the treatment of domestic sewage in controlled environments having the anaerobic process and specifically the upflow anaerobic sludge blanket (UASB) concept as the core, under natural hot conditions. The UASB process application is however beset by the preponderance of suspended solids, and the paper looks at its optimization via pre- and post-treatments to curb the prevailing problems, in the light of possible discharge and re-use/recycling/resource recovery, leading to efficient environmental protection. Pre-treatment clarification could be done with ferric chloride/polyelectrolyte, so that phosphate precipitates during the process. The pre-treated liquid phase can be submitted to a high rate anaerobic process, using the simple and robust UASB technology. In a subsequent post-treatment step, ammonium can be removed by ion exchange using a zeolite column through which the wastewater percolates after leaving the anaerobic digester. The various stages can also eliminate a large fraction of the pathogens present in the raw wastewater, mainly through the pre-treatment sedimentation and the ion exchange filtration. The sludge produced in the precipitation stage can be stabilized in a conventional anaerobic digester. Integration of the different treatment steps provides a sustainable technology to treat domestic sewage under hot climate conditions.

Bacteria, Anaerobic↗

PubMed2005

Management of young children with Rett disorder in the controlled multi-sensory (Snoezelen) environment.

Rett syndrome is a neurological disorder resulting from an X-linked dominant mutation. It is characterized by a variety of physical and perceptual disabilities, resulting in a need for constant therapy programs to be administered on a regular basis throughout the client's life. As the child with Rett disorder (RD) is entering the more obvious, hectic phase of this syndrome (stage II), signs of extreme agitation and discomfort are usually exhibited. This behavior is suspected to reflect damaging chaotic processes accruing in the brain at that time. Experts advise that calming techniques might be helpful for children with Rett during this period. This may be our earliest opportunity to change the course of the disorder. Now that our knowledge of RD has increased and children are being diagnosed at a substantially earlier age, new intervention methods should be introduced for parents and therapists. This may ensure more suitable treatment. The multi-sensory environment may provide a soothing haven, which appeals to the child with RD. This article provides a short review of RD typical phenotype and suggests suitable activities that could take place in the multi-sensory environment with this population at the early stages of appearance of the Rett disorder.

Environment, Controlled↗

PubMed2006

A spontaneous tonic chloride conductance in solitary glutamatergic hippocampal neurons.

GABA-A receptors mediate both phasic synaptic inhibition and more recently appreciated tonic currents in the vertebrate central nervous system. We addressed discrepancies in the literature regarding the pharmacology of tonic currents by examining tonic currents in a controlled environment of dissociated, solitary glutamatergic neurons. We describe a novel tonically active, bicuculline-sensitive chloride conductance that is insensitive to gabazine and to picrotoxin and thus not mediated by conventional GABA receptors. We exclude a significant contribution from small conductance calcium-gated potassium (SK) channels. We also pharmacologically exclude calcium-gated chloride channels, glycine receptors and the chloride current associated with glutamate transport. Finally, we demonstrate that, although small, this current modulates neuronal excitability. We speculate that this tonic current may provide a complementary mechanism for the regulation of neuronal excitability, particularly in regions with low ambient GABA concentrations. We conclude that this bicuculline-sensitive conductance needs to be accounted for in studies of GABA tonic currents, lest it be confused with currents associated with GABA overflow.

Animals↗