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PubMed2002

Applying sputum as a diagnostic tool in pneumonia: limited yield, minimal impact on treatment decisions.

STUDY OBJECTIVES: We evaluated the role of sputum examination in the management of patients with community-acquired pneumonia (CAP) in a primary-care hospital without microbiologic laboratory facilities. DESIGN AND INTERVENTIONS: A diagnostic strategy using regular collection of sputum samples, Gram staining in a local laboratory, and mailing of samples to a commercial laboratory for culture analysis. SETTING: A 200-bed primary-care hospital without subspeciality physicians. PATIENTS: One hundred sixteen consecutive patients with a diagnosis of CAP were prospectively evaluated during a 12-month period. RESULTS: Of 116 patients, 42 patients (36%) were capable of producing a sputum sample. Age > or = 75 years (odds ratio [OR], 0.4; 95% confidence interval [CI], 0.18 to 0.93) and prior ambulatory antimicrobial treatment (OR, 3.2; 95% CI, 1.2 to 8.4) were independent predictors of sputum production. A delay in collection and processing of sputum samples of > 24 h was present in 31% and 39%, respectively. A delay in collection yielded an increased number of Gram-negative enteric bacilli and nonfermenters (44% vs. 7%, p = 0.056). A delay in processing was associated with an increased number of Candida spp isolates (33% vs. 9%, p = 0.16). The overall diagnostic yield was low (10 of 116 patients, 9%) due to a limited number of valid samples (n = 23 of 42 patients, 55%) and a limited number of definitely or probably positive samples on Gram's stain and culture (n = 10 of 42 patients, 24%). Prior ambulatory antimicrobial treatment was associated with a reduction in diagnostic yield (14% vs. 56%, p = 0.09). The impact of diagnostic results on antimicrobial treatment decisions was minimal, with antimicrobial treatment directed to diagnostic results in only one patient. CONCLUSIONS: We conclude that in this setting representative of primary-care hospitals in Germany, sputum had a low diagnostic yield and did not contribute significantly to patient management.

Adult↗
PubMed2002

Blood cultures in the critical care unit: improving utilization and yield.

Sepsis is a common cause of morbidity and death in critically ill patients, and blood culture samples are often drawn in an effort to identify a responsible pathogen. Blood culture results are usually negative, however, and even when positive are sometimes difficult to interpret. Distinguishing between true bacteremia and a false-positive blood culture result is important, but complicated by a variety of factors in the ICU. False-positive culture results are costly because they often prompt more diagnostic testing and more antibiotic prescriptions, and increase hospital length of stay. A number of factors influence the yield of blood cultures in critically ill patients, including the use of antibiotics, the volume of blood drawn, the frequency with which culture samples are drawn, and the site from which the culture samples are taken. Skin preparation techniques, handling of the cultures in the microbiology laboratory, and the type of blood culture system employed also influence blood culture yield. Attempts to identify predictors of true bacteremia in critically ill patients have been disappointing. In this review, we discuss factors that influence blood culture yield in critically ill patients, suggest ways to improve yield, and discuss true bacteremia vs false-positive blood culture results. We also discuss the costs and consequences of false-positive blood culture results, and list noninfectious causes of fever in the ICU.

Bacteremia↗
PubMed1977

Bronchial brushing in bronchogenic carcinoma. Factors influencing cellular yield and diagnostic accuracy.

In a prospective study, varying the bronchial brushing technique through the flexible fiberoptic bronchoscope was examined for the effects of cellular yield and diagnostic accuracy. The yield of cells obtained from the 1.7-mm brush was increased by more than twofold when the brush and bronchoscope were withdrawn as a unit through the pharynx and nose, (nonwithdrawn brushing), rather than withdrawing the brush alone through the aspiration channel of the bronchoscope (withdrawn brushing). The greater number of total cells in the nonwithdrawn brushing specimen was largely due to squamous cells, and the yield of tumor cells by the two methods was similar. The yield of cells from the same brush withdrawn through a new suction adapter available on the bronchoscope (Olympus BF-B2) was significantly decreased, as compared with the withdrawn brushing. There was a further decrease using a shielded 1-mm brush. In 23 of 30 cases of proven carcinoma, the diagnosis was made by the single withdrawn brushing, and in 26 of the 30 by the single nonwithdrawn brushing, a difference which was not statistically significant. We conclude that diagnostic accuracy is not significantly enhanced by withdrawing the brush and bronchoscope as a unit through the pharynx and nose; use of a small shielded brush offers no advantage over a larger unshielded brush; modifications of flexible bronchoscopes, such as the adapter to improve efficacy of suction, should be evaluated for effects on harvests of cells from bronchial brushes before being put into general use.

Biopsy↗
PubMed2004

Yield point in prediction of compressive behavior of lumbar vertebral body by dual-energy x-ray absorptiometry.

The aims of the present study were to evaluate the influence of bone mineral content (BMC) and density on the behavior of the lumbar vertebra during compression and to determine critical points during compression. Dual-energy X-ray absorptiometry (DXA) and compression tests were performed on 44 vertebral bodies obtained from 22 cadavers. The results of the study indicate that bone mineral content measured by DXA were strongly correlated with ultimate failure load (r = 0.53, p < 0.001), ultimate failure stress (r = 0.581, p < 0.001), and toughness (r = 0.632, p < 0.001). Correlation with the yield point (r = 0.543, p < 0.001) was also significant. Bone mineral density showed similar results with ultimate failure load (r = 0.742, p < 0.001), ultimate failure stress (r = 0.742, p = 0.001), toughness (r = 0.673, p < 0.001), and yield point (r = 0.693, p < 0.001). The correlation between elastic parameters and DXA were suggestive but not quite significant. BMC was not related significantly with stiffness or Young's modulus. There was no correlation between bone mass and vertebral deformation parameters. In conclusion, bone mass and bone density appear to have a clear relationship to ultimate parameters and yield point. The relation with the yield point might be critical because it marks the beginning of the plastic region and signals the appearance of the first trabecular fractures.

Absorptiometry, Photon↗
PubMed2000

Impact of insecticides and surfactant on lettuce physiology and yield.

Insecticides are used extensively on lettuce, Lactuca sativa L., grown in southwestern Arizona because of heavy insect pressure that can potentially reduce lettuce productivity. Multiple sprays are made per season to manage these insects in lettuce. One of the major concerns related to extensive insecticide applications in lettuce is the potential subtle impact of insecticides that may reduce lettuce photosynthesis and yield. We conducted field and greenhouse experiments to examine the impact of multiple insecticides and surfactant spray applications on lettuce photosynthesis and yield. Lettuce was planted in the field in 1998, insecticides and surfactant were applied, and lettuce gas-exchange and dry weights were determined. Treatments were arranged in a split-plot consisting of insecticides as main plot and surfactant as subplot treatments in a randomized complete block design with four replications. Photosynthetic rates of lettuce were significantly reduced by endosulfan, methomyl, acephate, and surfactant at seedling stage 4 h and 2 d after the spray application was made. However, the reduction in lettuce photosynthesis by these insecticides and surfactant was only transient, and lettuce photosynthesis recovered 5 d after the spray application was made. Photosynthetic rates were not altered by zeta-cypermethrin, emamectin benzoate, and spinosad at the seedling stage. Insecticides or surfactant (Kinetic, a nonionic surfactant) did not significantly affect lettuce photosynthesis after rosette formation. In addition, lettuce dry weight was not significantly altered. These studies suggest that lettuce photosynthesis may be susceptible to some insecticides at the seedling stage. Consequently, we found that biorational insecticides, introduced to manage insect pests in lettuce, have no influence on lettuce physiology at the seedling stage, unlike the chlorinated hydrocarbons, organophosphates, or carbamates tested in this study. In a greenhouse study, we found that lettuce photosynthesis and yield were not altered by Bacillus thuringiensis application. Our results indicate that B. thuringiensis and the newer insecticides, particularly biorationals, can be used to manage lettuce insect pests without significantly altering lettuce gas-exchange and yield.

Animals↗
PubMed2001

Influence of western corn rootworm (Coleoptera: Chrysomelidae) larval injury on yield of different types of maize.

Two field experiments were conducted in 1995-1996 to determine if there are common yield responses among maize hybrids to larval western corn rootworm, Diabrotica virgifera virgifera LeConte injury. Three yellow dent hybrids, five white food grade dent hybrids, and a popcorn hybrid were included in the study. The minimum level of rootworm injury as measured by root damage ratings (3.2-4.2) that significantly reduced yield was similar across the hybrids included in the study. However, the pattern of yield response to different rootworm injury levels varied among hybrids. This suggests that maize hybrids may inherently differ in their ability to tolerate rootworm injury and partition biomass in response to injury and other stresses. The complex interaction among hybrid, level of injury, and other stresses suggests that a common western corn rootworm injury-yield relationship may not exist within maize.

Animals↗
PubMed2005

Proactive spraying against boll weevils (Coleoptera: Curculionidae) reduces insecticide applications and increases cotton yield and economic return.

The current standard practice of two to three preemptive insecticide applications at the start of pinhead (1-2-mm-diameter) squaring followed by threshold-triggered (whenever 10% of randomly selected squares have oviposition punctures) insecticide applications for boll weevil, Anthonomus grandis grandis Boheman, control does not provide a reliably positive impact on cotton, Gossypium hirsutum L., yields in subtropical conditions. This study showed that four fewer spray applications in a "proactive" approach, where spraying began at the start of large (5.5- 8-mm-diameter) square formation and continued at 7- to 8-d intervals while large squares were abundant, resulted in fewer infested squares and 46-56% more yield than the standard treatment at two locations during 2004. The combination of fewer sprays and increased yield made the proactive approach 115-130% more profitable than the standard. The proactive approach entails protection only at the crop's most vulnerable stage (large squares) that, as a source of food, accelerates boll weevil reproduction. In contrast, the standard approach protects early season small squares and later season bolls, both of which contribute less to boll weevil reproduction than large squares. Proaction is an in-season crop protection approach that can be used to increase yield in individual fields during the same season and that could be incorporated into boll weevil eradication strategy that involves later diapause sprays. Because proaction is based on an important relationship between the cotton plant and boll weevil reproduction, the tactic will probably be effective regardless of climate or region.

Animals↗
PubMed2006

Yield and forage quality of glandular-haired alfalfa under alfalfa weevil (Coleoptera: Curculionidae) and potato leafhopper (Hemiptera: Cicadellidae) pest pressure in Virginia.

Cultivars of glandular-haired alfalfa, Medicago sativa L., such as '54H69', are currently available and marketed as being resistant to potato leafhopper, Empoasca fabae (Harris) (Hemiptera: Cicadellidae). 54H69 and a standard, nonglandular-haired alfalfa 'Choice' were evaluated at two locations in Virginia over a 3-yr period. Dry matter yields and concentrations of crude protein and acid detergent fiber were compared at the first, second, and third harvests. Overall, the two cultivars produced similar dry matter yields of comparable forage quality in the absence of insecticides at both locations in each year. Untreated 54H69 did not produce greater dry matter yields than untreated Choice under either light or heavier potato leafhopper pest pressure. Concentrations of crude protein did not vary between the two cultivars at any harvest. Some differences in concentrations of acid detergent fiber were detected between cultivars, but these differences were not consistent among years, harvests, or between locations. Further comparisons between untreated 54H69 and treated Choice were made, but few significant differences were detected in dry matter yields or forage quality. An economic analysis for the study indicated that a grower planting 54H69 would realize less net revenue than a grower planting Choice, largely because of the seed premium for the glandular-haired cultivar and the evident need to treat 54H69 with insecticide for control of alfalfa weevil, Hypera postica (Gyllenhal) (Coleoptera: Curculionidae), and potato leafhopper.

Animals↗
PubMed2003

The absolute number of peripheral blood CD34+ cells predicts a timing for apheresis and progenitor cell yield in patients with hematologic malignancies and solid tumors.

Retrospective analysis was conducted in 51 autologous peripheral blood progenitor cell (PBPC) collections using the Spectra AutoPBSC System from patients with hematologic malignancies and solid tumors to study the predictive value of CD34+ cell counts in the peripheral blood for the yield of CD34+ cells in the apheresis product. The correlation coefficients for CD34+ cells microL(-1) of peripheral blood with CD34+ cell yield (x 10(6) kg(-1) of body weight and x 10(5) kg(-1) of body weight L(-1) of blood processed) were 0.903 and 0.778 (n=51 collections), respectively. Products collected from patients with CD34+ cell counts below 15 microL(-1) in the peripheral blood contained a median of 0.49 x 10(6) CD34+ cells kg(-1) (range: 0.05-2.55), whereas those with CD34+ cell counts more than 15 microL(-1) contained a median of 3.72 x 10(6) CD34+ cells kg(-1) (range: 1.06-37.57). From these results, a number of at least 15 CD34+ cells microL(-1) in the peripheral blood ensured a minimum yield of 1 x 10(6) CD34+ cells kg(-1) as obtained by a single apheresis procedure. The number of CD34+ cells in the peripheral blood can be used as a good predictor for timing of apheresis and estimating PBPC yield. With regard to our results, apheresis with a possibly poor efficiency should be avoided because the collection procedure is time-consuming and expensive.

Adolescent↗
PubMed1992

Milking frequency alters the milk yield and mammary blood flow response to intra-mammary infusion of insulin-like growth factor-I in the goat.

The milk yield and mammary blood flow responses to close-arterial, intra-mammary infusion of IGF-I were investigated in five Saanen goats milked frequently or normally the day before. Animals were infused for 6 h with recombinant human IGF-I (1.3 nmol/min) and milked hourly following i.v. injection of oxytocin beginning 2 h before infusion and then every 2 h. On one occasion animals were milked five times (after i.v. injection of oxytocin) on the day before infusion and on the other they were milked twice, without oxytocin. The ratio of milk yield from the infused to that from non-infused gland increased by 17 +/- 4% (mean +/- S.E.M.) in goats milked twice the day before infusion and by 6 +/- 2% when the infusion was preceded by frequent milking. Maximal responses were obtained 4 h after the start of the infusion and differed significantly (P < 0.05), according to pretreatment milking. Blood flow through the infused gland rose in parallel to the milk yield response. At 5 h, when maximal levels were achieved, blood flow was 182 +/- 23% of the pre-infusion flow rate following twice-daily milking and 139 +/- 3% of the pre-infusion flow rate following more frequent milk removal. Thus, more frequent milk removal on the day before close-arterial infusion of IGF-I attenuated both the milk yield and mammary blood-flow response to the infusion of IGF-I.

Animals↗
PubMed1994

Short-term oxytocin treatment increases bovine milk yield by enhancing milk removal without any direct action on mammary metabolism.

The milk yield-enhancing effect of oxytocin administered either before or after milking was examined using a within-animal model. Eight cows in mid-lactation were changed from normal twice daily milking to a split-milking design, whereby half of the udder was milked at 0500 and 1500 h (control half; normal milking times), and the other half at 0800 and 1800 h (test half). This continued for 3 weeks. During the second week, oxytocin was administered as an i.m. injection immediately before the 0800 and 1800 h milkings. The test half was thus milked immediately after oxytocin administration, whilst the control half was milked 3 h before oxytocin. Milk yield decreased slightly on the adoption of split-milking. The decrease did not differ between udder halves and was not, therefore, due to inadequate milk-ejection in the test half compared with the control. During the week of oxytocin treatment, the yield decreased further in the control half but increased in the test half; consequently, the yield from the test half was significantly greater than that from the control half (P < 0.05). The ratio of change in the test half relative to that in the control half was 1.12, significantly different from unity (P = 0.002). Analysis of variance demonstrated a significant (P < 0.001) interaction between udder half and oxytocin treatment, confirming that the effect of oxytocin was restricted to the test half, treated immediately before milking. This supports the established view that oxytocin acts by enhancing the milk-ejection reflex, and refutes a recent claim that the hormone has a direct stimulatory action on mammary metabolism.

Analysis of Variance↗
PubMed1996

Effects of diurnal control in the mineral concentration of nutrient solution on tomato yield and nutrient absorption in hydroponics.

We researched effects of diurnal change of the mineral concentration on tomato yield and nutrient absorption. First, we examined the effect on yield in a spray culture, in the experiment 1-1, when nitrate concentration of solution (N) and potassium concentration (K) were low and phosphate concentration (P) was high during the daytime, while N and K were high and P was low during the night, the yield was low. In the experiment 1-2, when N and K were high and P was low during the daytime, while N and K were low and P was high during the night, the yield was low. Second, we examined the effect on nutrient absorption in a water culture. Concentration of KNO3, of solution was changed in the daytime or the night. When KNO3 level was low during the daytime, while it was high during the night, total nitrate and potassium absorption for 24 hours was the highest. It were showed the possibility of the efficient supply of minerals to plants by the diurnal control in minerals.

Biomass↗
PubMed2001

Effect of the excitation source on the quantum-yield measurements of rhodamine B laser dye studied using thermal-lens technique.

A dual-beam transient thermal-lens technique was employed for the determination of absolute fluorescence quantum-yield measurements of Rhodamine B laser dye in different solvents. We investigated the effect of excitation on the absolute fluorescence quantum yield of Rhodamine B. 514 nm radiation from an argon ion laser was used as a cw excitation source and 532 nm pulses from a Q-switched Nd:YAG laser were used as a pulsed excitation source. The fluorescence quantum-yield values were found to be strongly influenced by environmental effects as well as the transient nature of the excitation beam. Our results also indicate that parameters, like the concentration of the dye solution, aggregate formation and excited state absorption, affect the absolute values of the fluorescence yield significantly.

Journal Article↗
PubMedDate not supplied

Growth and yield responses of potato to mixtures of carbon dioxide and ozone.

Elevated carbon dioxide (CO2) concentrations in the atmosphere can stimulate plant growth and yield, whereas ground-level ozone (O3) concentrations cause the opposite effect in many areas of the world. Recent experiments show that elevated CO2 can protect some plants from O3 stress, but this has not been tested for most crop species. Our objective was to determine if elevated CO2 protects Irish potato (Solanum tuberosum L.) from foliar injury and suppression of growth and yield caused by O3. An O3-resistant cultivar (Superior) and an O3-sensitive cultivar (Dark Red Norland) were exposed from within 10 d after emergence to maturity to mixtures of three CO2 and three O3 treatments in open-top field chambers. The three CO2 treatments were ambient (370 microL L(-1)) and two treatments with CO2 added to ambient CO2 for 24 h d(-1) (540 and 715 microL L(-1)). The O3 treatments were charcoal-filtered air (15 nL L(-1)), nonfiltered air (45 nL L(-1)), and nonfiltered air with O3 added for 12 h d(-1) (80 nL L(-1)). Elevated O3 and CO2 caused extensive foliar injury of Dark Red Norland, but caused only slight injury of Superior. Elevated CO2 increased growth and tuber yield of both cultivars, whereas elevated O3 generally suppressed growth and yield, mainly of Dark Red Norland. Elevated CO2 appeared to protect Dark Red Norland from O3-induced suppression of shoot, root, and tuber weight as measured at midseason but did not protect either cultivar from O3 stress at the final harvest. The results further illustrate the difficulty in predicting effects of O3 + CO2 mixtures based on the effects of the individual gases.

Air Pollutants↗
PubMed2006

Assessing alternatives for mitigating net greenhouse gas emissions and increasing yields from rice production in China over the next twenty years.

Assessments of the efficacy of mitigation of greenhouse gas (GHG) emissions from paddy rice systems have typically been analyzed based on field studies. Extrapolation of the mitigation potential of alternative management practices from field studies to a national scale may be enhanced by spatially explicit process models, like the DeNitrification and DeComposition (DNDC) model. Our objective was to analyze the impacts of mitigation alternatives, management of water, fertilizer, and rice straw, on net GHG emissions (carbon dioxide, methane, and nitrous oxide fluxes), yields, and water use. After constructing a GIS database of soil, climate, rice cropping area and systems, and management practices, we ran DNDC with 21-yr alternative management schemes for each of the approximately 2500 counties in China. Results indicate that, despite large-scale adoption of midseason drainage, there is still large potential for additional methane reductions from Chinese rice paddies of 20 to 60% over 2000-2020. However, changes in management for reducing CH4 emissions simultaneously affect soil carbon dynamics as well as N2O emissions and can thereby reorder the ranking of technical mitigation effectiveness. The order of net GHG emissions reduction effectiveness found here is upland rice > shallow flooding > ammonium sulfate > midseason drainage > off-season straw > slow-release fertilizer > continuous flooding. Most of the management alternatives produced yields comparable to the baseline; however, continuous flooding and upland rice significantly reduced yields. Water management strategies appear to be the most technically promising GHG mitigation alternatives, with shallow flooding providing additional benefits of both water conservation and increased yields.

Air Pollutants↗
PubMedDate not supplied

Photoperiod shift effects on yield characteristics of rice.

Edible yield must be maximized for each crop species selected for inclusion in the Controlled Ecological Life-Support System (CELSS) proposed by NASA to support long-term manned space missions. In a greenhouse study aimed at increasing biomass partitioning to rice (Oryza sativa L.) grain, plants of the high yielding semi-dwarf rice cultivar Ai-Nan-Tsao were started in pots under 8-h photoperiods at a density of 212 plants m-2. After different periods of time under 8-h photoperiods, pots were switched to continuous light for the remainder of the cropping cycle. Continuous light did not delay time to first panicle emergence (60 d) or time to harvest (83 d). There was a positive correlation between the length of continuous light treatments and nongrain biomass. Grain yield (1.6 +/- 0.2 g plant-1) did not increase in continuous light. Yield-efficiency rate (grain weight per length of cropping cycle, canopy volume, and weight of nongrain shoot biomass) was used to compare treatments. Small Ai-Nan-Tsao rice canopies grown under 8-h photoperiods were more efficient producers of grain than canopies grown under continuous light for a portion of the rice cropping cycle.

Biomass↗
PubMed2001

Comparison of bending modulus and yield strength between outer stratum medium and stratum medium zona alba in equine hooves.

OBJECTIVE: To determine whether the bending modulus and yield strength of the outer stratum medium (SM) differed from those of the SM zona alba (SMZA) and to what degree they differed. In addition, a comparison was made among our values and values reported elsewhere. SAMPLE POPULATION: 10 normal equine feet. PROCEDURE: A 3-point bending technique was used to determine the bending modulus and yield strength of the outer SM and SMZA. Efforts were made to minimize biological and technical factors that could influence the bending modulus. RESULTS: Bending modulus of the outer SM was (mean +/- SD) 187.6 +/- 41.3 MPa, whereas mean value for the SMZA was 98.2 +/- 36.8 MPa. Mean yield strength was 19.4 +/- 2.6 MPa for the outer SM and 5.6 +/- 1.7 MPa for the SMZA. Values for bending modulus and yield strength differed significantly between the outer SM and SMZA. Significant differences were not detected when the outer SM was loaded in bending from the outer or inner surface. CONCLUSIONS AND CLINICAL RELEVANCE: Potentially, the SMZA could serve as a mechanical buffer zone between the rigid hoof wall and bone and laminar tissues. This buffer zone potentially assists the feet of horses in transmitting a load through the tissues and prevents the most susceptible tissues from becoming damaged. More consistency among tissue selection, preparation, and testing protocols must be attained before an accurate 3-dimensional finite-element model of an equine foot can be constructed.

Animals↗
PubMed2002

Effect of lameness on milk yield in dairy cows.

OBJECTIVE: To examine the relationship between lameness and milk yield in dairy cows. DESIGN: Cohort study. ANIMALS: 531 dairy cows. PROCEDURE: Cows affected with lameness were classified into 1 of 3 groups on the basis of type of diseases or lesions observed, including interdigital phlegmon (foot rot), papillomatous digital dermatitis (foot warts), or claw lesions. Cows not affected with lameness were classified as healthy. From Dairy Herd Improvement Association records, 305-day mature equivalent milk yield data were collected at the end of lactation or when the cow left the herd. Milk yield was compared between cows affected with lameness and healthy cows. RESULTS: 167 (31%) cows were affected with lameness during lactation. Lame cows had claw lesions (60%), papillomatous digital dermatitis (31%), or interdigital phlegmon (9%). Milk yield in lame cows with interdigital phlegmon (mean, 17,122 lb) was significantly less, compared with healthy cows (19,007 lb). CONCLUSIONS AND CLINICAL RELEVANCE: In this herd, interdigital phlegmon was associated with a 10% decrease in milk production. Lame cows with claw lesions or papillomatous digital dermatitis produced less milk than healthy cows, but the difference was not significant.

Animals↗