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PubMed1971

Behavior of Corn and Sorghum under Water Stress and during Recovery.

Corn (Zea mays L.) and sorghum (Sorghum vulgare, Pers.) plants were grown in a vermiculite-gravel mixture in controlled environment chambers until they were 40 days old. Water was withheld until they were severely wilted, and they were then rewatered. During drying and after rewatering stomatal resistance was measured with a diffusion porometer each morning, and water saturation deficit and water potential were measured on leaf samples. The average resistance of the lower epidermis of well watered plants was lower for corn than for sorghum. When water stress developed, the stomata began to close at a higher water potential in corn than in sorghum. The stomata of both species began to reopen normally soon after the wilted plants were rewatered, and on the 2nd day the leaf resistances were nearly as low as those of the controls. The average leaf water potential of well watered corn was -4.5 bars; that of sorghum, -6.4 bars. The lowest leaf water potential in stressed corn was -12.8 bars at a water saturation deficit of 45%. The lowest leaf water potential in stressed sorghum was -15.7 bars, but the water saturation deficit was only 29%. At these values the leaves of both species were tightly rolled or folded and some injury was apparent. Thus, although the average leaf resistance of corn is little lower than that of sorghum, corn loses much more of its water before the stomata are fully closed than does sorghum. The smaller reduction in water content of sorghum for a given reduction in leaf water potential is characteristic of drought-resistant species.

Journal Article↗

PubMedDate not supplied

Influence of Campylobacter jejuni cecal colonization on immunoglobulin response in chickens.

The immunoglobulin response of chickens to colonization by Campylobacter jejuni isolates B-540 and Clin-1 was monitored. Chicken humoral IgG and biliary secretory IgA (sIgA) responses were assessed by enzyme-linked immunosorbent assay (ELISA). Samples were taken from 128 C. jejuni-colonized chickens and 104 uncolonized chickens housed in a controlled environment. An indirect ELISA was performed using the homologous isolate of C. jejuni as the capture antigen and was developed with the specific goat anti-chicken IgG or IgA alkaline phosphatase conjugates. The ELISA absorbance values of the test samples at 405 nm (serum diluted 1:32 and bile diluted 1:10) were normalized in direct proportion to standard sera and bile sample values. In the colonized chickens, humoral IgG activities were highest at hatch, dropped to their lowest level after 2 weeks, and increased by 8 weeks to levels similar to those detected at hatch. The sIgA activity was lowest at hatch and increased by 4 weeks in colonized chickens while remaining lower in the control chickens. Chickens colonized with isolate B-540 showed a primary sIgA response during the first 4 weeks and reached a plateau over the final 4 weeks. In spite of these limited humoral and secretory immunoglobulin responses, once the chicken ceca was colonized by C. jejuni, the organism persisted throughout the 8-week experiment.

Animals↗

PubMed2001

A murine model of smoke inhalation.

The United States has one of the world's largest per capita fire death rates. House fires alone kill >9,000 Americans annually, and smoke inhalation is the leading cause of mortality from structural fires. Animal models are needed to develop therapies to combat this problem. We have developed a murine model of smoke inhalation through the design, construction, and use of a controlled-environment smoke chamber. There is a direct relationship between the quantity of wood combusted and mortality in mice. As with human victims, the primary cause of death from smoke inhalation is an elevated blood carboxyhemoglobin level. Lethal (78%) and sublethal (50%) carboxyhemoglobin levels were obtained in mice subjected to varying amounts of smoke. Mice exposed to wood smoke demonstrated more dramatic pathology than mice exposed to cotton or polyurethane smoke. A CD-1 model of wood smoke exposure was developed, demonstrating type II cell hypertrophy, cytoplasmic blebbing, cytoplasmic vacuolization, sloughing, hemorrhage, edema, macrophage infiltration, and lymphocyte infiltration. The bronchoalveolar lavage fluid of smoke-exposed mice demonstrated a significant increase in total cell counts compared with those in control mice. These findings are comparable to the lung tissue response observed in human victims of smoke inhalation.

Animals↗

PubMed1994

Dental and oral hygiene student's knowledge of HIV infection and AIDS.

A survey was conducted to assess the knowledge of 30 oral hygiene (OH I & II) and 79 dental students (BCHD III & VI) on HIV infection and AIDS. A questionnaire consisting of twenty-nine questions based on the 'agree-disagree' format was prepared for this study. Clinical slides were projected to assess students' ability to identify oral manifestations of HIV infection. Most students agreed that HIV-sero-positive people were entitled to the same dignity and respect as those who were suffering from other illnesses. Students were concerned about treating sero-positive patients. They would preferably receive training in the management of these patients in a controlled environment. They had a poor perception of the risk of infection following needle-stick injury and whether HIV could be transmitted through contact with saliva. Most students felt that they had insufficient lectures on HIV/AIDS and had practically no clinical exposure to HIV-sero-positive patients.

Acquired Immunodeficiency Syndrome↗

PubMed2004

Behaviour of the three-spined stickleback, Gasterosteous aculeatus (Gasterosteidae, Teleostei) in the multispecies freshwater biomonitor: a validation of automated recordings at three levels of ammonia pollution.

The validity of using an automated online biomonitoring system, the multispecies freshwater biomonitor (MFB), in recording the physiological and behavioural activities of the three-spined stickleback Gasterosteous aculeatus, is assessed. The direct impact of the alternating electrical current generated by the impedance converter on fish activity was measured using a repeated measures design, machine on/machine off. Twelve subjects were used in each of three experimental groups: (1). standard hard water environment (control), (2). 0.1mM NH(4)Cl and (3). 10mM NH(4)Cl. Impedance generated waves were compared to corresponding manually recorded behavioural observations in an attempt to calibrate the MFB, assigning particular behaviours to a particular frequency and amplitude range. Data analysis suggests that the MFB current did not affect fish behaviour at any of the three contamination levels studied. Furthermore, analysis of the frequency with which behavioural activity changed (activity phases classified as inactive or active) showed that MFB behavioural data was not significantly different from that recorded manually. This suggested that the MFB recorded the behaviours that were concurrently observed. The feasibility of using the MFB as an effective behavioural early warning system in an aquacultural environment and as a scientific tool for toxicity testing is discussed.

Ammonium Chloride↗

PubMed1997

Onset of action, efficacy, and safety of a single dose of fexofenadine hydrochloride for ragweed allergy using an environmental exposure unit.

BACKGROUND: Fexofenadine hydrochloride is the active acid metabolite of terfenadine. Fexofenadine's anti-allergic properties require confirmation in a clinical setting. OBJECTIVE: The purpose of this study was to characterize the time to onset of clinically important relief of symptoms of allergic rhinitis in subjects taking single doses of either 60 mg or 120 mg fexofenadine HCl, or placebo, after exposure to ragweed pollen in a controlled environment. Other objectives were to assess the efficacy and safety of single doses of fexofenadine HCl. METHODS: One hundred forty-six ragweed-sensitive subjects were primed in the off-season with ragweed pollen in the environmental exposure unit. One hundred thirty-six subjects who adequately responded to priming entered a single-dose placebo phase. Placebo-responders were disqualified from the study, leaving 99 subjects with adequate symptoms to be randomized and given a single dose of either fexofenadine HCl 120 mg (33), 60 mg (33) or placebo (33), after 60 minutes of allergen exposure. Exposure continued over five hours and subjects recorded symptoms every 20 minutes. This study was of a randomized, placebo-controlled, double-blind, parallel design. RESULTS: Median time to onset for relaxed criteria clinically important relief was 60 minutes for both fexofenadine treatment groups, and 100 minutes for placebo (P = .018). The proportion with relief was 82% at 60 mg, 85% at 120 mg, and 64% for placebo. Treated groups had reductions in symptom scores double that of placebo. CONCLUSIONS: Fexofenadine is safe and efficacious at single doses of 60 mg and 120 mg. Average time to onset was 60 minutes using controlled pollen exposure in an environmental exposure unit.

Adolescent↗

PubMed1982

Environmental influences on semen output.

Semen output characteristics of 7,858 ejaculates of 57 commercial Holstein sires in artificial insemination were analyzed to estimate effects of environment over 3-yr. Large differences existed between bulls, first and second ejaculates, and intervals between collections for all measures of semen output. Effects of age of bulls were greatest for sperm concentration per milliliter and total sperm output, peaking at 4 yr of age. Original semen volume was influenced less by age. December was the best month for total sperm production even though June and July were the months for most volume of seminal fluid production. Total sperm output was highest on Fridays and lowest on Wednesdays. Effects of temperature and humidity and changes in temperature and humidity on semen output were small and inconsistent. These results do not support the assumption that semen output could be increased in controlled environment conditions.

Age Factors↗

PubMed2003

Farming in space: environmental and biophysical concerns.

The colonization of space will depend on our ability to routinely provide for the metabolic needs (oxygen, water, and food) of a crew with minimal re-supply from Earth. On Earth, these functions are facilitated by the cultivation of plant crops, thus it is important to develop plant-based food production systems to sustain the presence of mankind in space. Farming practices on earth have evolved for thousands of years to meet both the demands of an ever-increasing population and the availability of scarce resources, and now these practices must adapt to accommodate the effects of global warming. Similar challenges are expected when earth-based agricultural practices are adapted for space-based agriculture. A key variable in space is gravity; planets (e.g. Mars, 1/3 g) and moons (e.g. Earth's moon, 1/6 g) differ from spacecraft orbiting the Earth (e.g. Space stations) or orbital transfer vehicles that are subject to microgravity. The movement of heat, water vapor, CO2 and O2 between plant surfaces and their environment is also affected by gravity. In microgravity, these processes may also be affected by reduced mass transport and thicker boundary layers around plant organs caused by the absence of buoyancy dependent convective transport. Future space farmers will have to adapt their practices to accommodate microgravity, high and low extremes in ambient temperatures, reduced atmospheric pressures, atmospheres containing high volatile organic carbon contents, and elevated to super-elevated CO2 concentrations. Farming in space must also be carried out within power-, volume-, and mass-limited life support systems and must share resources with manned crews. Improved lighting and sensor technologies will have to be developed and tested for use in space. These developments should also help make crop production in terrestrial controlled environments (plant growth chambers and greenhouses) more efficient and, therefore, make these alternative agricultural systems more economically feasible food production systems.

Agriculture↗

PubMed2005

[Treatment of residents in 74 nursing homes: the opinion of caregivers].

This study is based on the outcomes of the program "Privacy In Nursing Homes" that has been initiated by the Dutch Department of Health in the late 90's. In this study, personnel of 74 nursing homes were asked to reflect on the way they treat residents. The attitudes of personnel were measured with a questionnaire that contains 80 propositions about their behaviour towards residents. The propositions can be reduced to five factors: kindness, structural environment, control, freedom to choose, and respect. First, we give the general results on these five factors. After that we give insight in the correlations between the five different aspects of treatment and the results of regression analysis. The general conclusion is that the behaviour towards residents in nursing homes at the beginning of the 21st Century is far from optimal. Residents most notably lack personal freedom and control over their received care and their way of living. This result is especially worrying because client conformed care has been an important point of attention for some time now. Another important conclusion is that the care for residents has a positive relation with the mangement policy of an organization and so, it is possible to improve the care.

Activities of Daily Living↗

PubMed2000

Outcomes assessment and minimally invasive surgery: historical perspective and future directions.

BACKGROUND: Outcomes assessment is being used increasingly to shape practice patterns in all areas of medicine. Although outcomes assessment is not a new concept, the widespread application of outcomes measurement for modifying practice is novel. Instead of focusing on results of interventions in highly controlled environments, outcomes studies usually report results as they occur in uncontrolled, real-world environments. Recently, the Society of American Gastrointestinal Endoscopic Surgeons (SAGES) has initiated a society-wide initiative to monitor outcomes in patients undergoing various laparoscopic operations. METHODS: Pertinent literature is reviewed as it relates to outcomes assessment. The historical background underpinning the modern interest in outcomes is outlined. Definitions of terms useful for understanding outcomes research are given. The impact of outcomes assessment on minimally invasive surgery, both positive and negative, are examined. The SAGES outcome initiative is introduced. CONCLUSIONS: Although outcomes studies usually do not provide information on the causes of observations made, they have gained in popularity because they provide information about patient perceptions of disease, disability, and treatment. Minimally invasive surgical procedures often are reported in terms of outcomes assessment because a controlled clinical trial was rendered impossible by early and widespread application of laparoscopic surgery. The SAGES outcomes initiative will provide the necessary tools for the participation of surgeons in the process of practice profiling.

Forecasting↗

PubMed1989

Condensation of hypertrophic chondrocytes at the chondro-osseous junction of growth plate cartilage in Yucatan swine: relationship to long bone growth.

Chondrocytes of the cartilaginous growth plate are found in a spatial gradient of cellular differentiation beginning with cellular proliferation and ending with cellular hypertrophy. Although it is recognized that both proliferation and hypertrophy contribute significantly to overall bone growth, mechanisms acting on the chondrocyte to control the timing, the rate, and the extent of hypertrophy are poorly understood. Similarly, mechanisms acting on the terminal chondrocyte to cause its death at the chondro-osseous junction have not been investigated. In this study we examine the condensation of terminal hypertrophic chondrocytes in proximal and distal radial growth plates of Yucatan swine at 4 weeks of age. The animals were raised in a controlled environment where activity and feeding patterns were synchronized to a given time in the light/dark cycle. We analyzed cellular condensation both as a function of circadian rhythms in a 24-hr time period, and as a function of overall rate of growth. The data suggest that the magnitude of circadian influences on long bone growth is significantly damped at the level of the hypertrophic chondrocyte compared to that seen by previous investigators studying circadian influences on chondrocytic proliferation. Secondly, the condensation of hypertrophic chondrocytes at the chondro-osseous junction varies inversely with rate of growth in length of the bone. At any time period, a higher percentage of terminal chondrocytes in the condensed form was found in the slower-growing of the two growth plates. We relate these findings to current hypotheses concerning controls of chondrocytic hypertrophy and possible controls over the timing of hypertrophic cell death.

Animals↗

PubMed2000

Using stable isotope natural abundances (delta 15N and delta 13C) to integrate the stress responses of wild barley (Hordeum spontaneum C. Koch.) genotypes.

To integrate the complex physiological responses of plants to stress, natural abundances (delta) of the stable isotope pairs 15N/14N and 13C/12C were measured in 30 genotypes of wild barley (Hordeum spontaneum C. Koch.). These accessions, originating from ecologically diverse sites, were grown in a controlled environment and subjected to mild, short-term drought or N-starvation. Increases in total dry weight were paralleled by less negative delta 13C in shoots and, in unstressed and droughted plants, by less negative whole-plant delta 13C. Root delta 15N was correlated negatively with total dry weight, whereas shoot and whole-plant delta 15N were not correlated with dry weight. The difference in delta 15N between shoot and root varied with stress in all genotypes. Shoot-root delta 15N may be a more sensitive indicator of stress response than shoot, root or whole-plant delta 15N alone. Among the potentially most productive genotypes, the most stress-tolerant had the most negative whole-plant delta 15N, whether the stress was drought or N-starvation. In common, controlled experiments, genotypic differences in whole-plant delta 15N may reflect the extent to which N can be retained within plants when stressed.

Carbon Isotopes↗

PubMed2002

A field evaluation of the impact of transfer efficiency on worker exposure during spray painting.

This paper presents a mathematical model to predict breathing-zone overspray concentrations produced during spray painting as a function of the overspray generation rate, ventilation and work practices. The overspray generation rate required an estimate of the spray gun transfer efficiency, which was provided by a previously developed mathematical model. These models were evaluated in the field under two different scenarios: first in a controlled environment that approximated the assumptions of models, and then under actual spray painting conditions. Results from the first test showed the model overestimated transfer efficiency, but the measured exposures and predicted exposures were not significantly different. During actual spray painting operations, all task exposures were within a factor of three of the model predictions, and there was no statistical difference between the measured and predicted values. The predicted average exposure of each worker was within the 95% confidence interval. The overall mean exposure was within one standard error of the model prediction. The current study expands on the original exposure model by including a transfer efficiency model to provide a better estimate of the overspray generation rate. The theoretical foundation between exposure and its primary determinants is established, and this knowledge can be applied to design and can evaluate optimal control interventions. Also, the general methodology presented here for developing an exposure model is applicable to operations other than spray painting.

Aerosols↗

PubMed1988

Effects of nitrogen dioxide on biochemical and physiological characteristics of soybean.

One month old soybean (Glycine max (L.) Merrill) cv. 'Williams' plants were exposed to nitrogen dioxide (NO2 at 0.1, 0.2, 0.3, and 0.5 microl liter(-1) and carbon filtered air (control), 7 h per day for five days, under controlled environment. Data were collected on net photosynthetic rate (PN), stomatal resistance (SR), and dark respiration rate (DR), immediately following the fifth day of exposure and 24 h after termination of exposure. Chlorophyll a (Ch a), chlorophyll b (Ch b), total chlorophyll (tot Ch) and foliar nitrogen (N) were measured before and after exposures. Growth characteristics--relative growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR), and root shoot ratio (RSR) -- were computed for treated plants using standard growth equations. Increases of 18% and 23% in PN were observed immediately following exposure to 0.2 microl liter(-1) NO2 and after 24 h recovery period, respectively. With 0.5 microl liter(-1) NO2 treatment, reductions in PN of 23% and 50% were observed, immediately after exposure and following 24 h recovery, respectively. DR rates with 0.2 l liter(-1) treatment were higher than the control. Chlorophyll a and tot Ch showed significant reduction with 0.5 microl liter(-1) NO2 treatment. The percent reduction in Ch a and tot Ch with 0.5 microl liter(-1) NO2 were 45% and 47%, respectively. Increases in foliar nitrogen content after 0.2 and 0.3 microl liter(-1) NO2 treatments were 46% and 69%, respectively. Nitrogen dioxide at 0.5 microl liter(-1) reduced RGR and NAR by 47% and 51%, respectively. Leaf area ratio was 42% higher in 0.5 microl liter(-)1 NO2 treated plants, compared with the control; this increase was insufficient to compensate for the decrease in NAR resulting in a net decline in RGR. Nitrogen dioxide up to 0.2 microl liter(-1) increased PN and foliar-N content of soybean. With 0.5 microl liter(-1) NO2, significant decreases were observed in PN, leaf chlorophyll, foliar-N, NAR and RGR. Nitrogen dioxide up to 0.2 microl liter(-)1 has a favorable influence on overall growth characteristics of soybean; however, inhibitory effects were seen with NO2 treatment at 0.5 microl liter(-1).

Journal Article↗

PubMed2001

Photoperiodic control of dormancy in Sedum telephium and some other herbaceous perennial plants.

The environmental control of dormancy and flowering of the herbaceous perennial Sedum telephium was studied in controlled environments. Short photoperiods induced growth cessation and the formation of resting buds in both seedlings and mature plants, whereas long photoperiods resulted in immediate growth activation of dormant buds. No chilling was required for dormancy release, even in plants induced to dormancy and maintained at high temperature (21 degrees C) for more than 3 months. The critical photoperiod for dormancy release was about 15 h, a minimum of four long-day (LD) cycles (24 h) being required. The true photoperiodic nature of this response was ascertained by night interruption experiments. Flowering of S. telephium was found to have an obligatory LD requirement, with no requirement for vernalization. The critical photoperiod and minimum number of inductive cycles for floral induction were the same as for dormancy release. Dormancy release by long days was also obtained in preliminary experiments with three other herbaceous perennials. The eco-physiological significance of photoperiodic control of dormancy is discussed, and it is concluded that the mechanism ensures stability of winter dormancy, even under conditions of climatic warming.

Journal Article↗

PubMed2005

Determinants of biomass production in hybrid willows and prediction of field performance from pot studies.

Pot experiments are often performed to assess plant physiological traits and relationships among growth traits under controlled environments. However, the reliability of pot studies for predicting the growth and performance of trees in the field has rarely been rigorously assessed. We evaluated the suitability of pot experiments for predicting field performance, measured as shoot biomass production, by investigating determinants of growth in hybrid willows (Salix spp.) grown under various environmental conditions in the field, and by comparing the data with the results from a corresponding pot study. Biomass production in six hybrid willow clones, bred for use as bio-fuels, was assessed in three field trials located in central and southeastern Sweden throughout the first 3-year cutting cycle. The determinants of biomass productivity, measured as biomass allocation and nitrogen (N) economy, were identified in one of the field trials. Key traits for shoot biomass production in the field were total leaf area and total amount of N; plant N losses by shed leaves were only partly controlled by leaf-litter N concentration. These key traits were also obtained from the pot study and related to shoot biomass production and abscission-leaf N loss in the field. Total leaf area and total N pool of plants grown in pot experiments were good predictors of long-term biomass production in the field, whereas shoot biomass production, specific leaf area and tissue N concentration of pot-grown plants were less suitable as predictors of field performance. Relationships between the key traits and shoot biomass production were clone-specific, indicating the need for analysis of growth traits at the clone level if field performance of trees is to be evaluated based on data from pot studies. Nutrient loss components are important for tree performance in the long term and evaluations of nutrient loss characteristics at the individual-tree level should focus on nutrient pools lost rather than on nutrient concentrations in abscised plant parts.

Biomass↗

PubMed1984

Loline alkaloids in tall fescue hay and seed and their relationship to summer fescue toxicosis in cattle.

In three trials, young Holstein steers housed in restraint type crates in a controlled environment room were fed tall fescue hay or seed diets to determine the ability of the diets to produce signs of summer syndrome. Trial 1 examined the effects of dehydration and extended storage of G1-307 fescue compared to alfalfa on dairy steers. Calves fed G1-307 fescue had lower daily feed intake, higher rectal temperatures and respiration rates, and lost 13.4 kg more body weight during the experimental period as compared to those fed alfalfa hay. In trial 2, benomyl (a systemic fungicide) was used to eliminate the fungus Epichloe typhina from treated G1-307 fescue plants. Steers fed the treated G1-307 fescue progeny had higher daily intakes, lower rectal temperature, lower respiration rates, and lost less body weight over the trial period as compared with those fed untreated G1-307 fescue. Kenhy tall fescue seeds with and without analyzable N-acetyl and N-formyl loline alkaloids and a control diet were fed in trial 3. Steers fed the seed with the loline alkaloids had reduced intake, higher rectal temperatures, and lost 10.9 kg more body weight over the trial period than steers fed seed that did not contain loline alkaloids.

Animal Feed↗

PubMed2006

Pilot study to evaluate the accuracy of ultrasonography in confirming endotracheal tube placement.

STUDY OBJECTIVE: Visualization of the vocal cords and end-tidal capnography are the usual standards in confirming endotracheal tube placement. Vocal cord visualization is, however, not always possible, and capnography is not 100% reliable and requires ventilation of the lungs to confirm placement. The goal of this study is to determine the accuracy of ultrasonography for detecting endotracheal tube placement into the trachea and esophagus in real time. METHODS: This was a prospective, randomized, controlled study. Eligible patients were adults undergoing elective surgery requiring intubation. Exclusion criteria were a history of difficult intubation, abnormal airway anatomy, aspiration risk factors, and esophageal disease. Thirty-three patients were enrolled. After induction of anesthesia and neuromuscular blockade, the anesthesiologist placed the endotracheal tube in the trachea and esophagus in random order with direct laryngoscopy. During the intubations, a high-frequency, linear transducer was placed transversely on the neck at the suprasternal notch. Two emergency physicians, blinded to the order and performance of the intubations, independently recorded the location of the endotracheal tube according to the real-time ultrasonographic image. A 2-by-2 table was used to calculate sensitivity and specificity of the emergency physicians' ability to detect placement of the endotracheal tube. RESULTS: For each physician, the sensitivity for identifying the first intubation as tracheal was 100% (95% confidence interval [CI] 77% to 100%) with a specificity of 100% (95% CI 82% to 100%). One endotracheal tube was unintentionally placed twice in the esophagus, but both tube placements were identified as esophageal by the emergency physicians. CONCLUSION: In this pilot study, 2 emergency physicians experienced in ultrasonography accurately detected placement of endotracheal tubes during intubation with ultrasonography in select patients in the controlled environment of the operating room. Future studies should examine the use of ultrasonography to visualize endotracheal tube placement in real time by emergency physicians with less ultrasonographic training; use of the technique in the emergency department on a wider range of patients, including patients with difficult airways; and assessment of the utility of ultrasonography in confirmation of endotracheal tube position in already intubated patients.

Adult↗