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PubMed1984

Nutritional requirements of experimental fish.

Satisfactory fulfillment of the nutritional requirements of experimental fish under subchronic and chronic test conditions (such as carcinogenesis studies) is critical to the outcome of a study. Nutritional requirements of many coldwater, warmwater, and marine fishes have been determined in part by the use of semipurified diets. Generally, these diets were fed to small fish in controlled environment tanks with no supplemental food available. The control diets contained semipurified natural ingredients, or, when appropriate, purified (crystalline) nutrients and were formulated to meet the requirements (approximate) of the test species. We fed the fish representative diets to insure that their nutritional needs were met and that no adverse pathology would develop. We then modified these control diets by removing one or more of the purified nutrients to determine the essentiality of a dietary component. Later, other diets were formulated to contain different amounts of the essential nutrients, or one ingredient was substituted for another, so that the quantitative requirements could be decided. Thus we could determine the dietary requirements for protein, fat, carbohydrate, and bulk, and the qualitative and quantitative requirements for the individual amino acids, vitamins, fatty acids, and some minerals. Semipurified diets were later used in toxicity studies for the measurement of the effect of different levels of manufactured contaminants, such as insecticides, or natural toxicants, such as aflatoxin, on the well-being of fishes. Information on the preparation of semipurified diets for fishes, feeding techniques, and nutritional requirements as well as suggestions on care of small fishes in tanks appropriate for longer term carcinogenesis studies is provided.

Amino Acids↗

PubMed1979

Photosynthetic Adaptation of Solanum dulcamara L. to Sun and Shade Environments: II. Physiological Characterization of Phenotypic Response to Environment.

Photosynthetic and growth properties of Solanum dulcamara L. were studied under controlled environments. The 200 experimentally tested plants were clonal replicates of five field-collected individuals, three from fully exposed habitats and two from deeply shaded habitats. After 4 weeks of growth in one of eight environmental treatments, each plant was measured for leaf adaxial and abaxial conductance to water vapor, specific leaf weight, chlorophyll per square decimeter of leaf, photosynthetic unit size, light-saturated photosynthetic rate, total leaf area, and total leaf, stem, and root dry weights. Changes in light level influenced photosynthesis and growth of each plant more than changes in water availability or temperature. It is strongly suggested that the primary adaptive response of the tested individuals to changes in levels of light involves the regulation of leaf thickness.

Journal Article↗

PubMed2000

Fine tuning bacterial chemotaxis: analysis of Rhodobacter sphaeroides behaviour under aerobic and anaerobic conditions by mutation of the major chemotaxis operons and cheY genes.

Rhodobacter sphaeroides chemotaxis is significantly more complex than that of enteric bacteria. Rhodobacter sphaeroides has multiple copies of chemotaxis genes (two cheA, one cheB, two cheR, three cheW, five cheY but no cheZ), controlling a single 'stop-start' flagellum. The growth environment controls the level of expression of different groups of genes. Tethered cell analysis of mutants suggests that CheY(4) and CheY(5) are the motor-binding response regulators. The histidine protein kinase CheA(2) mediates an attractant ('normal') response via CheY(4), while CheA(1) and CheY(5) appear to mediate a repellent ('inverted') response. CheY(3) facilitates signal termination, possibly acting as a phosphate sink, although CheY(1) and CheY(2) can substitute. The normal and inverted responses may be initiated by separate sets of chemoreceptors with their relative strength dependent on growth conditions. Rhodobacter sphaeroides may use antagonistic responses through two chemosensory pathways, expressed at different levels in different environments, to maintain their position in a currently optimum environment. Complex chemotaxis systems are increasingly being identified and the strategy adopted by R.sphaeroides may be common in the bacterial kingdom.

Amino Acid Sequence↗

PubMed1996

Controlling ourselves, controlling our world. Psychology's role in understanding positive and negative consequences of seeking and gaining control.

This article begins by examining psychology's contributions to understanding the positive consequences of control for individual mental and physical health. Person-environment control mismatches and the negative personal, interpersonal, and societal consequences of seeking and having control are then discussed. As corrections to mismatches and negative consequences, three methods of analyses are provided. First, definitional and conceptual precision is offered, including a more careful matching of control-related interventions to multidimensional, individual-specific control profiles. Second, therapeutic assessment and interventions are placed within a biopsychosocial model of control. Finally, philosophy of science and paradigmatic issues underlying control theories are highlighted, particularly as they affect psychology's role in examining values toward which control efforts should be directed. These topics are important for people's personal and collective well-being.

Assertiveness↗

PubMed2001

Infection control issues after bone marrow transplantation.

Bone marrow transplant recipients are at increased risk of a variety of infections from endogenous and exogenous sources. Various practices, including the use of prophylactic agents and a controlled environment are often employed in the name of infection control. Comparable data are lacking because of non-unified definitions of infection and endpoints. Antibiotic-resistant bacteria and fungi are being isolated more frequently as a result of selective pressure.

Antifungal Agents↗

PubMed1997

Neural grafting to experimental neocortical infarcts improves behavioral outcome and reduces thalamic atrophy in rats housed in enriched but not in standard environments.

BACKGROUND AND PURPOSE: The purpose of this study was to evaluate whether grafting of fetal neocortical tissue 1 week after focal brain ischemia improved behavioral outcome and reduced secondary thalamic atrophy. METHODS: One week after distal ligation of the right middle cerebral artery in spontaneously hypertensive male rats, blocks of fetal neocortex (embryonic day 17) were homografted to rats housed in standard or enriched environments. Control infarcted nongrafted rats were housed in the enriched environment. Behavioral outcome was repeatedly tested until the rats were killed 20 weeks after the ligation. Ten days earlier, a mixture of 2% Fluoro-Gold and 10% biotinylated dextran amine was injected into the transplants for retrograde and anterograde tracing of graft-host connections. RESULTS: Grafted and nongrafted rats with enriched housing performed significantly better than grafted rats with standard housing on a rotating pole and a prehensile traction test. Grafted "enriched" rats were moreover significantly better than grafted "standard" rats and nongrafted enriched rats in a rotation test and a postural and locomotor tail position test. In the latter test, nongrafted enriched rats performed significantly better than grafted standard rats. The lesion-induced atrophy in posterior thalamus with its major sensorimotor cortex relay nuclei was significantly reduced in grafted enriched rats compared with nongrafted enriched rats. Afferent and efferent graft-host connections were identified in both grafted groups. Graft volumes did not differ. CONCLUSIONS: Neural grafting enhanced functional outcome and reduced thalamic atrophy only when combined with housing in enriched environments.

Animals↗

PubMed1982

[Repercussions of anterior hypothalamic lesions on nycthemeral variations of plasma thyroxine and corticosterone in the pigeon].

Plasma thyroxine and corticosterone levels were determined by competitive protein binding assay, at 3 hr intervals, throughout the photoperiod. Pigeons were kept in controlled environment (21 +/- 1 degree C; 14L6-20: 10D). Intact controls exhibited low thyroxine (T4) and corticosterone (B) levels for the light phase of the photoperiod. Values were rising during the night, up to a peak at 03 hr. Electrolytic lesions were placed bilaterally in either the nucleus anterior medialis hypothalami or the n. preopticus, or the n. supraopticus. Circadian rhythms of both T4 and B were markedly altered in all lesioned pigeons, with a shift of very high T4 values to the morning times and a complete disorganization of B patterns, with very heterogeneous values. The possibility is raised that anterior hypothalamic formations participate in the endogenous oscillator circuitry in birds.

Animals↗

PubMed2002

Treatment of chronic pain with spinal cord stimulation versus alternative therapies: cost-effectiveness analysis.

OBJECTIVE: There is limited available research measuring the cost-effectiveness of spinal cord stimulation (SCS), compared with best medical treatment/conventional pain therapy (CPT). The purpose of this study was to tabulate the actual costs (in Canadian dollars) for a consecutive series of patients treated with SCS in a constant health care delivery environment and to compare the costs with those for a control group treated in the same controlled environment. METHODS: We present a consecutive series of 104 patients with failed back syndrome. Within this group, 60 patients underwent SCS electrode implantation, whereas 44 patients were designated as control subjects. We monitored these patients for a 5-year period and tabulated the actual costs incurred in diagnostic imaging, professional fees paid to physicians, implantation (including the costs for hardware), nursing visits for maintenance of the stimulators, physiotherapy, chiropractic treatments, massage therapy, and hospitalization for treatment of breakthrough pain. From these data, the cumulative costs for each group were calculated for a 5-year period. An analysis of Oswestry questionnaire results was also performed, to evaluate the effects of treatment on the quality of life. RESULTS: The actual mean cumulative cost for SCS therapy for a 5-year period was $29,123/patient, compared with $38,029 for CPT. The cost of treatment for the SCS group was greater than that for the CPT group in the first 2.5 years. The costs of treating patients with SCS became less than those for CPT after that period and remained so during the rest of the follow-up period. In addition, 15% of SCS-treated patients were able to return to employment, because of superior pain control and lower drug intake. No patients in the control group were able to return to employment of any kind. CONCLUSION: SCS is cost-effective in the long term, despite the initial high costs of the implantable devices.

Back Pain↗

PubMed2002

Comparison of static and dynamic medium environments for culturing of pre-implantation mouse embryos.

The ability to manipulate mouse pre-implantation embryos in vitro has become a valuable tool in many scientific disciplines. However, fewer embryos maintain viability following in vitro manipulation compared with embryos in vivo. It has been suggested that use of dynamic medium environments may improve viability by simulating in utero environment. The objective of the study reported here was to compare a microdrop in vitro culture system with a microdevice in vitro culture system containing a static and two dynamic medium environments (0.1 and 0.5 microl/h) for culturing of mouse pre-implantation embryos. Results indicated that the static medium environment, in silicon-glass microdevices, was not significantly different from the microdrop control environment in proportion of embryos developing from the two-cell to the blastocyst stage. However, the static microdevice environment produced significantly (P < 0.05) more morulas than did that of the control group. Both of these treatment groups, under the presented conditions, consistently had significantly higher proportions of blastocysts (P < 0.05) and morulas (P < 0.05) and lower proportions of abnormal (P < 0.05) and eight-cell embryos (P < 0.05), compared with those of the high flow rate dynamic environment microdevice treatment groups. Studies exploring slower or pulsatile rates of medium delivery in a dynamic medium environment are indicated.

Animals↗

PubMed2001

Drought stress, plant water status, and floral trait expression in fireweed, Epilobium angustifolium (Onagraceae).

In a controlled environment, we artificially induced drought during flowering of Epilobium angustifolium, an animal-pollinated plant. Leaf water potential (ψ(l)) and floral traits were monitored over a 12-d period of soil moisture depletion. Soil moisture depletion induced drought stress over time, as revealed by significant treatment × day interactions for predawn and midday ψ(l). Nectar volume and flower size showed significant negative responses to drought stress, but nectar sugar concentration did not vary between treatments. Floral traits were more buffered from drought than leaf water potentials. We used path analysis to examine direct and indirect effects of ψ(l) on floral traits for plants in well-watered (control) vs. drought treatments. According to the best-fit path models, midday ψ(l) has significant positive effects on flower size and nectar volume in both environments. However, for controls midday ψ(l) also had a significant negative effect on nectar sugar concentration. Results indicate that traits influencing floral attractiveness to pollinators in E. angustifolium vary with plant water status, such that pollinator-mediated selection could indirectly target physiological or biochemical controls on ψ(l). Moreover, under mesic conditions selection for greater nectar sugar reward may be constrained by the antagonistic effects of plant water status on nectar volume and sugar concentration.

Journal Article↗

PubMed2006

Acute heat exposure increases high-intensity performance during sprint cycle exercise.

The purpose of this study was to investigate the effects of acute heat exposure at thermal balance on high-intensity performance during sprint cycle exercise. Nine healthy male subjects were tested in three different, well-controlled environments in an environmental chamber: T (22 degrees C, 65% RH), H1 (30 degrees C, 55% RH) and H2 (35 degrees C, 62% RH), each test being carried out on a different day following a randomized sequence. After 30 min of exposure to the set environment, subjects performed the 30-s sprint cycle exercise. Heart rate, rectal and skin temperatures were measured prior to exercise, at rest, before and after environmental exposure, and after exercise. There were no differences in subjects' core temperature or heart rate prior to exercise. However, skin temperature was significantly higher in hot trials compared with the control throughout the experimental session (P < 0.05). Peak power was significantly higher in the hot environments compared with the control. Mean power was higher only in H2 compared with T (P < 0.05). This difference in power output was the consequence of a faster pedaling cadence in the hot trials (P < 0.05). Plasma ammonia was higher in the hot trials versus control at 4 min post-sprint. No differences in blood lactate levels at 3 min post-sprint were observed between tests. The results of this study suggest that the exposure to hot environment caused an improvement in power output for a single 30-s sprint. This increase in power output was associated with an elevation in plasma ammonia suggestive of an increase in adenine nucleotide loss.

Ammonia↗

PubMedDate not supplied

Benzodiazepine-resistant "brown fat" pattern in positron emission tomography: two case reports of resolution with temperature control.

PURPOSE: Supraclavicular uptake of 2-deoxy-2-[18F]fluoro-D-glucose (FDG) on positron emission tomography (PET) scan is attributed to lymph node, muscle, or brown fat activity. Differentiation between physiological or pathological etiologies is necessary. Benzodiazepine premedication to reduce physiological uptake has been attempted with variable success. A relationship between brown-fat FDG uptake and cold temperature has also been established. To our knowledge, no case reports or studies have been published to demonstrate whether controlling the temperature can alter the physiological uptake in these regions. PROCEDURES: Two teenage female patients with these patterns on PET scans performed with oral benzodiazepine administration underwent repeat imaging with temperature-controlled environment settings. RESULTS: Resolution of supraclavicular FDG uptake with temperature control in two patients in whom benzodiazepine had no prior effect. CONCLUSION: Although the exact mechanism remains unknown, we propose that the control of temperature reduces the metabolism of glucose by brown fat. Further studies are warranted to confirm the above observations, and, if confirmed, to determine the most efficient and effective use of temperature control to minimize supraclavicular and axillary FDG uptake.

Adipose Tissue, Brown↗

PubMed2004

The nature of long-term care nursing work.

Data from a pilot study on the nature of nursing work in long-term care (LTC) facilities are compared with data on nursing work in intensive care units (ICUs). The comparison suggests that the LTC nursing work environment is a complex, demanding, and interesting one that is different from, not less than, nursing work in acute care environments. The data also suggests that nursing educators and researchers should reconsider LTC nursing work environments. Long-term care nursing offers an ideal, relatively controlled environment for research on what nursing work is and how nursing interventions affect patient outcomes. Long-term care nurses, whose daily work has always involved working with a variety of professional and unlicensed staff members, can serve as models for delegation and interpersonal skills. Finally, the LTC setting offers the ideal environment for clinical sites in connection with the proposed curriculum changes in end-of-life care for patients and their families.

Aged↗

PubMed1996

Implementation of a computer-controlled life support system in the acceleration research environment.

Electronic control of the G-valve and pressure breathing regulator is being implemented in some advanced life support systems used in aircrew protection. This technological improvement, however, has not reached its full potential in the research environment. A computer-controlled life support system interface providing programmable schedules for G-suit inflation and positive pressure breathing during +Gz (PBG) was developed. Output pressures from a G-valve and pressure breathing regulator (Carleton Technologies) were controlled by a Macintosh computer running LabVIEW software. Required pressures were determined as functions of single or multiple control inputs (i.e. +Gz level, a pressure signal, time, etc.). Subject safety was ensured via hardware limitations and status checks incorporated into the software. Experiments conducted at +1 Gz and at various +Gz levels evaluated the computer software-life support hardware interface. Open-loop algorithms allowed independent control of multiple regulators using simple (single input) and complex (multiple input with adaptive loop) control structures. The system provided accurate and reproducible G-suit and mask pressures. Time of inflation, peak pressure attained, and deflation rate were effectively controlled at all +Gz levels. The ability to alter the pressure schedules independent of +Gz or time allowed comprehensive control over all parameters necessary to conduct acceleration research involving advanced life support systems.

Aerospace Medicine↗

PubMed2006

Management of Rett syndrome in the controlled multisensory (Snoezelen) environment. A review with three case stories.

Rett syndrome (RS) 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 continuous intervention programs to be administered on a regular basis throughout life. Many of these individuals with RS show fear of movement and, therefore, find it hard to accept external facilitation (so common in physical therapy intervention). In a search for novel intervention techniques that might improve their ability to cope with difficulties in daily situations, while also reducing their difficulty in handling motion inflicted by an external physical facilitator, we examined the use of the Snoezelen room. The Snoezelen, also known as the controlled multisensory environment, can provide a soothing atmosphere that appeals to the individual with RS, while at the same time it can improve physical, sensorial, and functional abilities. This article suggests various intervention goals that are appropriate for individuals with RS at different stages of the disorder. Since the management of young children with RS in the multisensory environment has been discussed at length in the past, this article will mainly describe intervention with adults with RS, focusing on three case stories. The present article reviews the available scientific materials on the topic of Snoezelen, incorporating clinical knowledge in the field of RS and suggesting this approach as an appropriate intervention method for this population.

Adult↗

PubMed2005

Environmental enrichment promotes neurogenesis and changes the extracellular concentrations of glutamate and GABA in the hippocampus of aged rats.

The aim of the present study was to investigate the effects of environmental enrichment on the neurogenesis and the extracellular concentrations of glutamate and GABA in the hippocampus of freely moving young and aged rats. Male Wistar rats of 2 (young) and 25 (old) months of age were housed during 8 weeks in an enriched environment; control rats were kept in individual plastic cages during that same period of time. Rats were injected intraperitoneally with bromodeoxyuridine (BrdU; 40 mg/kg; 7 days) during the fourth week of the housing period to detect neurogenesis in the dentate gyrus (DG) of the hippocampus. Rats were sacrified 6 weeks after the last injection of BrdU. During the last week of housing, rats were tested in the water maze for the evaluation of spatial learning. After the housing period, rats were stereotaxically implanted with guide-cannulas to accommodate microdialysis probes in the CA3 area of the hippocampus and the extracellular concentrations of glutamate and GABA were determined. Aged rats showed a decrease in the number of BrdU positive cells in the dentate gyrus compared to young rats. However, neurogenesis in the dentate gyrus of both young and old rats was increased in animals housed in an enriched environment. Microdialysis experiments in the CA3 area of the hippocampus showed that enriched housing conditions increased basal extracellular concentrations of glutamate in aged rats. Perfusion of KCl 100 mM produced a higher increase of extracellular glutamate and GABA in aged rats but not in young rats housed in an enriched environment compared to control rats. These results suggest that enriched housing conditions change both neurogenesis in the dentate gyrus and glutamate and GABA levels in the CA3 area of the hippocampus of aged rats.

Aging↗

PubMed1994

Creep of a poly(etherurethane urea) in an oxidative environment.

The creep behavior of a PEUU without added stabilizers was examined in H2O2/CoCl2, an environment that simulates the biodegradation of this polymer. Creep in the control environments, air, water, and H2O2, was logarithmic with time as is characteristic of primary or viscoelastic creep. At short times, creep in H2O2/CoCl2 followed the same time dependency as creep in H2O2; however, at longer times an acceleration in the creep rate was observed. Creep in H2O2/CoCl2 was satisfactorily described by addition of a linear time term to the creep equation with an induction time, ti. The induction time was extended by stress-induced crystallization of the soft segments, but was reduced by an increase in H2O2 concentration. Oxidative degradation of the PEUU soft segments was detected by infrared and GPC analysis at times less than ti. This led to the speculation that an initial "precursor" layer was created at the surface by chain cleavage. Microcracking in a subsequent stage was postulated to be responsible for the observed effect on the creep behavior.

Biocompatible Materials↗

PubMed2000

Benthic fluxes of cadmium, lead, copper and nitrogen species in the northern Adriatic Sea in front of the River Po outflow, Italy.

Trace heavy metal (Cd, Pb and Cu) and nitrogen species (N-NO3, N-NO2 and N-NH4) fluxes between sediment and water were examined for approximately 4 days, in a coastal marine station located in the northern Adriatic Sea in front of the River Po outflow. An in situ benthic chamber, equipped with electronic devices for monitoring and adjustment of oxygen and pH and with a temperature detector, was used. The benthic chamber experiment enabled study of the temporal trend of metals and nutrients when oxygen concentration varied in a controlled environment. Although particular care was devoted to chamber deposition and parameter control, sediment resuspension occurred at the beginning of the experiment and O2 fluctuations were observed during the course of the experiment. Pb concentration was affected by both resuspension and oxic conditions in bottom water, which prevented determination of any reasonable Pb flux value. Cd and Cu, not influenced by oxygen fluctuations, reached an equilibrium phase in a short period with initial positive fluxes from sediment of 0.68 (S.D. = 0.07) and 6.9 (S.D. = 5.6) pmol cm(-2) h(-1), respectively. With regard to nitrogen species, the highest positive flux was that of N-NH4 (10.5, S.D. = 2.4, nmol cm(-2) h(-1)) whose concentration increased in the chamber, while nitrate concentration (initial flux of -5.7, S.D. = 1.5, nmol cm(-2) h(-1)) immediately decreased after the beginning of the experiment. Nitrite concentration was almost constant throughout the experiment and its flux was generally low (initial flux 0.1, S.D. = 0.9, nmol cm(-2) h(-1)).

Ammonia↗