Rumen microbial responses to supplemental nitrate. I. Yeast growth and protozoal chemotaxis in vitro as affected by nitrate and nitrite concentrations.

Nitrates have been fed to ruminants, including dairy cows, as an electron sink to mitigate CH4 emissions. In the NO3- reduction process, NO2- can accumulate, which could directly inhibit methanogens and some bacteria. However, little information is available on eukaryotic microbes in the rumen. Protozoa were hypothesized to enhance nitrate reductase but also have more circling swimming behavior, and the yeast Saccharomyces cerevisiae was hypothesized to lessen NO2- accumulation. In the first experiment, a culture of S. cerevisiae strain 1026 was evaluated under 3 growth phases: aerobic, anoxic, or transition to anoxic culture. Each phase was evaluated with a control or 1 of 3 isonitrogenous doses, including NO3-, NO2-, or NH4+ replacing peptone in the medium. Gas head phase, NO3-, or NH4+ did not influence culture growth, but increasing NO2- concentration increasingly inhibited yeast growth. In experiment 2, rumen fluid was harvested and incubated for 3 h in 2 concentrations of NO3-, NO2-, or sodium nitroprusside before assessing chemotaxis of protozoa toward glucose or peptides. Increasing NO2- concentration decreased chemotaxis by isotrichids toward glucose or peptides and decreased chemotaxis by entodiniomorphids but only toward peptides. Live yeast culture was inhibited dose-responsively by NO2- and does not seem to be a viable mechanism to prevent NO2- accumulation in the rumen, whereas a role for protozoal nitrate reductase and NO2- influencing signal transduction requires further research.

Rumen microbial responses to supplemental nitrate. II. Potential interactions with live yeast culture on the prokaryotic community and methanogenesis in continuous culture.

Nitrates have been fed to ruminants, including dairy cows, as an electron sink to mitigate CH4 emissions. In the NO3- reduction process, NO2- can accumulate, which could directly inhibit methanogens and possibly other microbes in the rumen. Saccharomyces cerevisiae yeast was hypothesized to decrease NO2- through direct reduction or indirectly by stimulating the bacterium Selenomonas ruminantium, which is among the ruminal bacteria most well characterized to reduce both NO3- and NO2-. Ruminal fluid was incubated in continuous cultures fed diets without or with NaNO3 (1.5% of diet dry matter; i.e., 1.09% NO3-) and without or with live yeast culture (LYC) fed at a recommended 0.010 g/d (scaled from cattle to fermentor intakes) in a 2 × 2 factorial arrangement of treatments. Treatments with LYC had increased NDF digestibility and acetate:propionate by increasing acetate molar proportion but tended to decrease total VFA production. The main effect of NO3- increased acetate:propionate by increasing acetate molar proportion; NO3- also decreased molar proportions of isobutyrate and butyrate. Both NO3- and LYC shifted bacterial community composition (based on relative sequence abundance of 16S rRNA genes). An interaction occurred such that NO3- decreased valerate molar proportion only when no LYC was added. Nitrate decreased daily CH4 emissions by 29%. However, treatment × time interactions were present for both CH4 and H2 emission from the headspace; CH4 was decreased by the main effect of NO3- until 6 h postfeeding, but NO3- and LYC decreased H2 emission up to 4 h postfeeding. As expected, NO3- decreased methane emissions in continuous cultures; however, contrary to expectations, LYC did not attenuate NO2- accumulation.

Untreated Gleason Grade Progression on Serial Biopsies during Prostate Cancer Active Surveillance: Clinical Course and Pathological Outcomes.

PURPOSE: We describe the outcomes of patients with low risk localized prostate cancer who were upgraded on a surveillance biopsy while on active surveillance and evaluated whether delayed treatment was associated with adverse outcome. MATERIALS AND METHODS: We included men in the study with lower risk disease managed initially with active surveillance and upgraded to Gleason score 3+4 or greater. Patient demographics and disease characteristics were compared. Kaplan-Meier curve was used to estimate the treatment-free probability stratified by initial upgrade (3+4 vs 4+3 or greater), Cox regression analysis was used to examine factors associated with treatment and multivariate logistic regression analysis was used to evaluate the factors associated with adverse outcome at surgery. RESULTS: The final cohort comprised 219 men, with 150 (68%) upgraded to 3+4 and 69 (32%) to 4+3 or greater. Median time to upgrade was 23 months (IQR 11-49). A total of 163 men (74%) sought treatment, the majority (69%) with radical prostatectomy. The treatment-free survival rate at 5 years was 22% for 3+4 and 10% for 4+3 or greater upgrade. Upgrade to 4+3 or greater, higher prostate specific antigen density at diagnosis and shorter time to initial upgrade were associated with treatment. At surgical pathology 34% of cancers were downgraded while 6% were upgraded. Cancer volume at initial upgrade was associated with adverse pathological outcome at surgery (OR 3.33, 95% CI 1.19-9.29, p=0.02). CONCLUSIONS: After Gleason score upgrade most patients elected treatment with radical prostatectomy. Among men who deferred definitive intervention, few experienced additional upgrading. At radical prostatectomy only 6% of cases were upgraded further and only tumor volume at initial upgrade was significantly associated with adverse pathological outcome.

Multi-state trials of Bt sweet corn varieties for control of the corn earworm (Lepidoptera: Noctuidae).

Field tests in 2010-2011 were performed in New York, Minnesota, Maryland, Ohio, and Georgia to compare Bt sweet corn lines expressing Cry1A.105 + Cry2Ab2 and Cry1Ab with their non-Bt isolines, with and without the use of foliar insecticides. The primary insect pest in all locations during the trial years was Heliocoverpa zea (Boddie), which is becoming the most serious insect pest of sweet corn in the United States. At harvest, the ears were measured for marketability according to fresh market and processing standards. For fresh market and processing, least squares regression showed significant effects of protein expression, state, and insecticide frequency. There was a significant effect of year for fresh market but not for processing. The model also showed significant effects of H. zea per ear by protein expression. Sweet corn containing two genes (Cry1A.105 + Cry2Ab2) and a single gene (Cry1Ab) provided high marketability, and both Bt varieties significantly outperformed the traditional non-Bt isolines in nearly all cases regardless of insecticide application frequency. For pest suppression of H. zea, plants expressing Bt proteins consistently performed better than non-Bt isoline plants, even those sprayed at conventional insecticide frequencies. Where comparisons in the same state were made between Cry1A.105 + Cry2Ab2 and Cry1Ab plants for fresh market, the product expressing Cry1A.105 + Cry2Ab2 provided better protection and resulted in less variability in control. Overall, these results indicate Cry1A.105 + Cry2Ab2 and Cry1Ab plants are suitable for fresh market and processing corn production across a diversity of growing regions and years. Our results demonstrate that Bt sweet corn has the potential to significantly reduce the use of conventional insecticides against lepidopteran pests and, in turn, reduce occupational and environmental risks that arise from intensive insecticide use.

Sweet Corn Sentinel Monitoring for Lepidopteran Field-Evolved Resistance to Bt Toxins.

As part of an insect resistance management plan to preserve Bt transgenic technology, annual monitoring of target pests is mandated to detect susceptibility changes to Bt toxins. Currently Helicoverpa zea (Boddie) monitoring involves investigating unexpected injury in Bt crop fields and collecting larvae from non-Bt host plants for laboratory diet bioassays to determine mortality responses to diagnostic concentrations of Bt toxins. To date, this monitoring approach has not detected any significant change from the known range of baseline susceptibility to Bt toxins, yet practical field-evolved resistance in H. zea populations and numerous occurrences of unexpected injury occur in Bt crops. In this study, we implemented a network of 73 sentinel sweet corn trials, spanning 16 U.S. states and 4 Canadian provinces, for monitoring changes in H. zea susceptibility to Cry and Vip3A toxins by measuring differences in ear damage and larval infestations between isogenic pairs of non-Bt and Bt hybrids over three years. This approach can monitor susceptibility changes and regional differences in other ear-feeding lepidopteran pests. Temporal changes in the field efficacy of each toxin were evidenced by comparing our current results with earlier published studies, including baseline data for each Bt trait when first commercialized. Changes in amount of ear damage showed significant increases in H. zea resistance to Cry toxins and possibly lower susceptibility to Vip3a. Our findings demonstrate that the sentinel plot approach as an in-field screen can effectively monitor phenotypic resistance and document field-evolved resistance in target pest populations, improving resistance monitoring for Bt crops.

Epidemiology of tuberculous infection in a chronic care population.

A prospective study of serial tuberculin skin testing was performed on 642 patients from the chronic care wards of a Veterans Administration Hospital. Five hundred eighty-eight patients without a documented history of tuberculosis or a positive tuberculin skin test received an initial 5 TU PPD, and results in 139 were positive (23.6%). Of those initially tuberculin negative, 398 received a second 5 TU PPD 2 to 4 wk later; 45 (11.3%) showed a booster effect. Of the initial 642 patients, 64 had documented negative tuberculin skin tests within the year preceding the survey. Eight (12.5%) of the 64 patients were positive at the initial survey. There were 213 patients with 2 negative tuberculin tests within the first 4 wk of the study who were followed for the year of the study, and 10 converted their tuberculin skin test for a converter rate of 4.7%. The decrease in the converter rate from 12.5 to 4.7% suggests that the initial converter rate was falsely elevated by the booster effect. The high rate of conversion during the year of the study (4.7%) suggests that there may have been inapparent spread of tuberculous infection among patients in this chronic care facility.

Determinants of response to eucapneic hyperventilation with cold air in a population-based study.

A population-based, epidemiologic investigation conducted in children, adolescents, and young adults analyzed the response to eucapneic hyperventilation with cold air as a continuous variable to better define factors that influence the expression of bronchial responsiveness. Among respiratory illness/symptom variables, only the report of asthma or persistent wheeze in the previous year and the report of a respiratory illness that led to activity restriction were significantly associated with response to cold air. Furthermore, a low, prechallenge FEF/FVC ratio was a significant predictor of response, especially among those subjects who reported a respiratory illness that led to activity restriction. This relationship was not observed for a low prechallenge FEF.

The relationship of airways responsiveness to cold air, cigarette smoking, and atopy to respiratory symptoms and pulmonary function in adults.

The response to eucapnic hyperventilation with subfreezing air was studied in a population based sample of 171 adults, all of whom also completed a respiratory questionnaire, spirometry, and skin testing. A positive response to the cold air challenge was defined as [initial FEV1-post-challenge FEV1)/initial FVC) X 100) greater than or equal to 9%. Cigarette smoking was with a positive cold air response: 12 of 128 current and ex-smokers (9.4%) versus 1 of 43 nonsmokers (2.3%) (p = 0.095). Among current and ex-smokers, a positive response to the cold air challenge was significantly associated with asthma (p = 0.046). Using a logistic regression model, both current smoking and response to cold air were significant predictors of the presence of "persistent wheeze" or asthma. A positive skin test to any of the 4 environmental antigens used (ragweed, housedust, trees, and grasses) was significantly associated with cigarette smoking (p = 0.018) and hay fever (p = 0.003 among current and ex-smokers) but not with wheezing or asthma. Though not statistically significant, cold air responders had a lower percentage of positive skin test reactivity than nonreactors. The findings of this cross-sectional analysis suggest that in adults, both airways responsiveness and cigarette smoking are important predictors of wheezing and asthma. Furthermore, the data suggest that airway hyperresponsiveness and atopy are independent traits. However, in adults, these traits are associated with cigarette smoking, a common environmental exposure.