Rhizosphere soil has a more diverse and active microbial community compared to nonvegetated soil. Consequently, the rhizosphere pyrene degrader population (PDP) and pyrene degradation may be enhanced ...compared to nonvegetated bulk soil (NVB). The objectives of this growth chamber study were to compare (1) Bermuda grass (Cynodon dactylon cv. Guymon) growth in pyrene-contaminated and noncontaminated soils and (2) pyrene degradation and PDP among NVB, Bermuda grass bulk (BB), and Bermuda grass rhizosphere soil (BR). Soils were amended with pyrene at 0 and 500 mg kg^sup -1^, seeded with Bermuda grass, and thinned to two plants per pot 14 days after planting (DAP). Pyrene degradation was evaluated over 63 days. The PDP was enumerated via a most probable number (MPN) procedure at 63 DAP. Bermuda grass root growth was more sensitive to pyrene contamination than shoot growth. Pyrene degradation followed first-order kinetics. Pyrene degradation was significantly greater in BR compared to BB and NVB with rate constants of 0.082, 0.050, and 0.052 day^sup -1^, respectively. The PDPs were 8.01, 7.30, and 6.83 log^sub 10^ MPN g^sup -1^ dry soil for BR, BB, and NVB, respectively. The largest PDP was in soil with the most rapid pyrene degradation. These results indicate that Bermuda grass can grow in pyrene-contaminated soil and enhance pyrene degradation through a rhizosphere effect.PUBLICATION ABSTRACT
Rhizosphere microbial populations in contaminated soils Nichols, T.D. (Arkansas Univ., Fayetteville, AR (USA). Dept. of Agronomy); Wolf, D.C; Rogers, H.B ...
Water, air, and soil pollution,
04/1997, Letnik:
95, Številka:
1-4
Journal Article
Recenzirano
Rhizosphere microbial populations may increase bioremediation of soil contaminated with organic chemicals. A growth chamber study was conducted to evaluate rhizosphere microbial populations in ...contaminated and non-contaminated soil. Alfalfa (Medicago sativa L.) and alpine bluegrass (Poa alpina L.) were grown in soil containing a mixture of organic chemicals for 14 weeks. The equal millimolar mixture of hexadecane, (2,2-dimethylpropyl)benzene, cis-decahydronaphthalene (decalin), benzoic acid, phenanthrene, and pyrene was added at levels of 0 and 2000 mg/kg. Organic chemical degrader (OCD) populations were assessed by a Most-Probable-Number technique, and bacteria and fungi were enumerated by plate count methods. Different methods for expressing OCD rhizosphere populations were investigated to determine the effect it had on interpretation of the results. At 9 weeks, the OCD numbers were significantly higher in rhizosphere and contaminated soils than in bulk and non-contaminated soils, respectively. Alfalfa rhizosphere OCD levels were 4 × 107/g for contaminated and 6 × 106/g for non-contaminated soils. Bluegrass rhizosphere OCD levels were 1 × 107/g and 1 × 106/g in contaminated and non-contaminated soils, respectively. Selective enrichment of OCD populations was observed in contaminated rhizosphere soil. Higher numbers of OCD in contaminated rhizospheres suggest potential stimulation of bioremediation around plant roots.
Ceftazidime-avibactam is a novel cephalosporin-beta-lactamase inhibitor combination that is active against many carbapenem-resistant
(CRE). We describe a retrospective chart review for 60 patients ...who received ceftazidime-avibactam for a CRE infection. In-hospital mortality was 32%, 53% of patients had microbiological cure, and 65% had clinical success. In this severely ill population with CRE infections, ceftazidime-avibactam was an appropriate option.
Abstract
Background
Real-world data assessing outcomes of immunocompromised patients treated with ceftolozane/tazobactam (C/T) are limited. This study evaluated treatment and clinical outcomes of ...immunocompromised patients receiving C/T for multidrug-resistant (MDR) Pseudomonas aeruginosa.
Methods
This was a 14-center retrospective cohort study of adult immunocompromised inpatients treated for ≥24 hours with C/T for MDR P. aeruginosa infections. Patients were defined as immunocompromised if they had a history of previous solid organ transplant (SOT), disease that increased susceptibility to infection, or received immunosuppressive therapies. The primary outcomes were all-cause 30-day mortality and clinical cure.
Results
Sixty-nine patients were included; 84% received immunosuppressive agents, 68% had a history of SOT, and 29% had diseases increasing susceptibility to infection. The mean patient age was 57 ± 14 years, and the median (interquartile range) patient Acute Physiology and Chronic Health Evaluation II and Charlson Comorbidity Index scores were 18 (13) and 5 (4), respectively, with 46% receiving intensive care unit care at C/T initiation. The most frequent infection sources were respiratory (56%) and wound (11%). All-cause 30-day mortality was 19% (n = 13), with clinical cure achieved in 47 (68%) patients. Clinical cure was numerically higher (75% vs 30%) in pneumonia patients who received 3-g pneumonia regimens vs 1.5-g regimens.
Conclusions
Of 69 immunocompromised patients treated with C/T for MDR P. aeruginosa, clinical cure was achieved in 68% and mortality was 19%, consistent with other reports on a cross-section of patient populations. C/T represents a promising agent for treatment of P. aeruginosa resistant to traditional antipseudomonal agents in this high-risk population.
Rhizosphere microbial populations may increase bioremediation of soil contaminated with organic chemicals. A growth chamber study was conducted to evaluate rhizosphere microbial populations in ...contaminated and non-contaminated soil. Alfalfa (Medicago sativa L.) and alpine bluegrass (Poa alpina L.) were grown in soil containing a mixture of organic chemicals for 14 weeks. The equal millimolar mixture of hexadecane, (2,2-dimethyl-propyl)-benzene, cis-decahydronaphthalene (decalin), benzoic acid, phenanthrene, and pyrene was added at levels of 0 and 2000 mg/kg. Organic chemical degrader (OCD) populations were assessed by a Most-Probable-Number technique, and bacteria and fungi were enumerated by plate count methods. Different methods for expressing OCD rhizosphere populations were investigated to determine the effect it had on interpretation of the results. At 9 weeks, the OCD numbers were significantly higher in rhizosphere and contaminated soils than in bulk and non-contaminated soils, respectively. Alfalfa rhizosphere OCD levels were 4 × 10^sup 7^/g for contaminated and 6 × 10^sup 6^/g for non-contaminated soils. Bluegrass rhizosphere OCD levels were 1 × 10^sup 7^/g and 1 × 10^sup 6^/g in contaminated and non-contaminated soils, respectively. Selective enrichment of OCD populations was observed in contaminated rhizosphere soil. Higher numbers of OCD in contaminated rhizospheres suggest potential stimulation of bioremediation around plant roots.PUBLICATION ABSTRACT
Multidrug-resistant
infections remain common in hospitals worldwide. We investigated the outcomes associated with the use of ceftolozane-tazobactam for the treatment of these infections.
Data were ...collected retrospectively from 20 hospitals across the United States about adults who received ceftolozane-tazobactam for the treatment of multidrug-resistant
infections of any source for at least 24 hours. The primary outcome was a composite of 30-day and inpatient mortality, and secondary outcomes were clinical success and microbiological cure. Multivariable regression analysis was conducted to determine factors associated with outcomes.
Two-hundred five patients were included in the study. Severe illness and high degrees of comorbidity were common, with median Acute Physiology and Chronic Health Evaluation (APACHE) II scores of 19 (interquartile range IQR, 11-24) and median Charlson Comorbidity Indexes of 4 (IQR, 3-6). Delayed initiation of ceftolozane-tazobactam was common with therapy started a median of 9 days after culture collection. Fifty-nine percent of patients had pneumonia. On susceptibility testing, 125 of 139 (89.9%) isolates were susceptible to ceftolozane-tazobactam. Mortality occurred in 39 patients (19%); clinical success and microbiological cure were 151 (73.7%) and 145 (70.7%), respectively. On multivariable regression analysis, starting ceftolozane-tazobactam within 4 days of culture collection was associated with survival (adjusted odds ratio OR, 5.55; 95% confidence interval CI, 2.14-14.40), clinical success (adjusted OR, 2.93; 95% CI, 1.40-6.10), and microbiological cure (adjusted OR, 2.59; 95% CI, 1.24-5.38).
Ceftolozane-tazobactam appeared to be effective in the treatment of multidrug-resistant
infections, particularly when initiated early after the onset of infection.
Cancer screenings aid in the early detection of cancer and can help reduce cancer-related mortality. The current model of care for cancer screening is often siloed, based on the targeted cancer site. ...We tested the acceptability of a new model of care, called the One-Stop-Shop Cancer Screening Clinic, that centralizes cancer screenings and offers patients the option to complete all their recommended cancer screenings within one to two visits. We administered surveys to 59 community members and 26 healthcare providers to gather feedback about the One-Stop-Shop model of care. Both community members and providers identified potential benefits (e.g., decreased patient burden, increased completion of cancer screenings) and also potential challenges (e.g., challenges with workflow and timing of care) of the model of care. The results of the study support the acceptability of the model of care. Of the community members surveyed, 89.5% said, if offered, they would be interested in participating in the One-Stop-Shop Cancer Screening Clinic. Future studies are needed to formally evaluate the impact and cost effectiveness of the One-Stop-Shop Cancer Screening Clinic.Cancer screenings aid in the early detection of cancer and can help reduce cancer-related mortality. The current model of care for cancer screening is often siloed, based on the targeted cancer site. We tested the acceptability of a new model of care, called the One-Stop-Shop Cancer Screening Clinic, that centralizes cancer screenings and offers patients the option to complete all their recommended cancer screenings within one to two visits. We administered surveys to 59 community members and 26 healthcare providers to gather feedback about the One-Stop-Shop model of care. Both community members and providers identified potential benefits (e.g., decreased patient burden, increased completion of cancer screenings) and also potential challenges (e.g., challenges with workflow and timing of care) of the model of care. The results of the study support the acceptability of the model of care. Of the community members surveyed, 89.5% said, if offered, they would be interested in participating in the One-Stop-Shop Cancer Screening Clinic. Future studies are needed to formally evaluate the impact and cost effectiveness of the One-Stop-Shop Cancer Screening Clinic.
Data on root parameters and distribution are important for an improved understanding of the factors influencing nutrient uptake by a crop. Therefore, a study was conducted on a Crowley silt loam at ...the Rice Research and Extension Center near Stuttgart, Arkansas to measure root growth and N, P and K uptake by three rice (Oryza sativa L.) cultivars at active tillering (36 days after emergence (DAE)), maximum tillering (41 DAE), 1.25 cm internode elongation (55 DAE), booting (77 DAE) and heading (88 DAE). Soil-root core samples were taken to a depth of 40 cm after plant samples were removed, sectioned into 5 cm intervals, roots were washed from soil and root lengths, dry weights and radii were measured. Root parameters were significantly affected by the soil depth × growth stage interaction. In addition, only root radius was affected by cultivar. At the 0- to 5-cm soil depth, root length density ranged from 38 to 93 cm cm⁻³ throughout the growing season and decreased with depth to about 2 cm cm⁻³ in the 35- to 40-cm depth increment. The increase in root length measured with each succeeding growth stage in each soil horizon also resulted in increased root surface area, hence providing more exposed area for nutrient uptake. About 90% of the total root length was found in the 0- to 20-cm soil depth throughout the season. Average root radius measured in the 0- to 5-cm and 35- to 40-cm depth increments ranged from 0.012 to 0.013 cm and 0.004 to 0.005 cm, respectively throughout the season. Total nutrient uptake by rice differed among cultivars only during vegetative growth. Differences in total nutrient uptake among the cultivars in the field appear to be related to absorption kinetics of the cultivars measured in a growth chamber study.
Delayed application and/or early draining of floodwater to lowland irrigated rice (
Oryza sativa L.) should allow producers in southern USA more time for ground application of chemicals while ...reducing potential hazards from aerial applications and conserving water. Two field studies were conducted to evaluate growth and yield responses of “Tebonnet”, “Alan”, and “Texmont” rice to reduced flood duration and altered N management. Depending upon the study, treatments consisted of normal (four- to five-leaf stage) or delayed timing of flood application in combination with recommended or earlier-than-recommended draining of the floodwater, and full-season flush irrigation. Nitrogen was either applied once at the four- to five-leaf stage or as a three-way split with normal- or earlier-than-recommended timing. Flush irrigation reduced shoot and root growth and yield of rice as compared to normal flood while delayed-flood irrigation reduced shoot dry weight but had no effect on root length density or grain and head-rice yields. Nitrogen uptake was greater with a single preflood application of N than with a three-way split application. Yields were not affected by N management or earlier-than-recommended draining of the floodwater. These data indicate that the duration of floodwater application currently practiced in rice production in southern USA may be reduced without sacrificing grain yield or quality.
Medical and public health scientists are using evolution to devise new strategies to solve major health problems. But based on a 2003 survey, medical curricula may not adequately prepare physicians ...to evaluate and extend these advances. This study assessed the change in coverage of evolution in North American medical schools since 2003 and identified opportunities for enriching medical education.
In 2013, curriculum deans for all North American medical schools were invited to rate curricular coverage and perceived importance of 12 core principles, the extent of anticipated controversy from adding evolution, and the usefulness of 13 teaching resources. Differences between schools were assessed by Pearson's chi-square test, Student's t-test, and Spearman's correlation. Open-ended questions sought insight into perceived barriers and benefits.
Despite repeated follow-up, 60 schools (39%) responded to the survey. There was no evidence of sample bias. The three evolutionary principles rated most important were antibiotic resistance, environmental mismatch, and somatic selection in cancer. While importance and coverage of principles were correlated (r = 0.76, P < 0.01), coverage (at least moderate) lagged behind importance (at least moderate) by an average of 21% (SD = 6%). Compared to 2003, a range of evolutionary principles were covered by 4 to 74% more schools. Nearly half (48%) of responders anticipated igniting controversy at their medical school if they added evolution to their curriculum. The teaching resources ranked most useful were model test questions and answers, case studies, and model curricula for existing courses/rotations. Limited resources (faculty expertise) were cited as the major barrier to adding more evolution, but benefits included a deeper understanding and improved patient care.
North American medical schools have increased the evolution content in their curricula over the past decade. However, coverage is not commensurate with importance. At a few medical schools, anticipated controversy impedes teaching more evolution. Efforts to improve evolution education in medical schools should be directed toward boosting faculty expertise and crafting resources that can be easily integrated into existing curricula.
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