Research Notes : United States : Evaluation of soybean germplasm for stress tolerance and biological efficiency : To evaluate soybean germplasm and cultivars for stress tolerance toward - Pest and Diseases

A total of 1,273 soybean germplasm lines and 39 commercial varie-ties were screened for natural resistance to Mexican bean beetle (MBB) under field conditions. There were 421, 314, 266, 136, and 136 germplasm and varieties from maturity groups VI, VII, VIII, IX, and X, respectively. An average of 1,000 laboratory-reared adult MBB per day were released uniformly over all the field throughout the growing season from May until September to create an adequate MBB infestation

Research Notes : United States : Evaluation of soybean germplasm for stress tolerance and biological efficiency towards : Pests

One of the major objectives of the proposal is systematic screening of all available soybean germplasm of Maturity Groups III to VIII for a natural resistance to a major insect pest, the Mexican bean beetle (MBB). These six Maturity Groups (III-VIII) cover abouL 5,000 plant introductions (Pis), 350 commercial varieties, and 80 breeding lines. Selected accessions of the most resistant (35% or less leaf defoliation) and highly susceptible (over 75% leaf defoliation) in general screening under field conditions were re-evaluated in triplicate in 1985 and in quadruplicate in 1986 (Table 2). About 20 special selections were evaluated for MBB under controlled environmental conditions

A Hierarchical Bayesian Design for Phase I Trials of Novel Combinations of Cancer Therapeutic Agents

We propose a hierarchical model for the probability of dose-limiting toxicity (DLT) for combinations of doses of two therapeutic agents. We apply this model to an adaptive Bayesian trial algorithm whose goal is to identify combinations with DLT rates close to a prespecified target rate. We describe methods for generating prior distributions for the parameters in our model from a basic set of information elicited from clinical investigators. We survey the performance of our algorithm in a series of simulations of a hypothetical trial that examines combinations of four doses of two agents. We also compare the performance of our approach to two existing methods and assess the sensitivity of our approach to the chosen prior distribution.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78700/1/j.1541-0420.2009.01363.x.pd

Phase I study of irinotecan and raltitrexed in patients with advanced astrointestinal tract adenocarcinoma

To determine the dose-limiting toxicities (DLT) and maximum tolerated dose (MTD) of irinotecan and raltitrexed given as sequential short infusions every 3 weeks, 33 patients with pretreated gastrointestinal adenocarcinoma (31 colorectal, 2 oesophagogastric) entered this open label dose-escalation study. For the first five dose levels patients received irinotecan 175–350 mg m–2followed by raltitrexed 2.6 mg m–2. Level VI was irinotecan 350 mg m–2plus raltitrexed 3.0 mg m–2, level VII was irinotecan 400 mg m–2plus raltitrexed 2.6 mg m–2; 261 courses were administered. Only one patient at dose levels I–V experienced DLT. At level VI, 5/12 patients experienced DLT: one had grade 3 diarrhoea and lethargy, one had grade 4 diarrhoea and one had lethargy alone. Two others had lethargy caused by disease progression. There was no first-cycle neutropenia. At level VII, 3/6 patients experienced dose-limiting lethargy, one also had grade 3 diarrhoea. Dose intensity fell from over 90% for both drugs at level VI to 83% for irinotecan and 66% for raltitrexed at level VII. Lethargy was therefore the DLT, and level VII the MTD. Pharmacokinetic data showed no measurable drug interaction; 6/30 patients (20%) had objective responses. This combination is active with manageable toxicity. Recommended doses for further evaluation are irinotecan 350 mg m–2and raltitrexed 3.0 mg m–2. © 2000 Cancer Research Campaig

The Rumen methanogen community and diurnal activity in pasture based dairy cows of the South Island

The South Island of New Zealand offers a novel medium for studying methanogen community because dairy cows are fed almost exclusively on pasture and yet have unusually high milk production due to high dry matter intakes from high quality pastures. This study was conducted to investigate the population structure and diurnal activity profiles of the resident methanogen community in pasture fed cows in this system, using the effect of various dietary supplementations. Since there are no current techniques available to satisfactorily measure actual methane production within the diurnal period in free grazing animals, molecular techniques were adapted and used for this research. Denaturing gradient gel electrophoresis (DGGE) was used for the intial screening of the populations. Similar to previous studies, Methanobrevibacter sp.was found to be the predominant methanogen. Though the supplements (grain, fat and monensin) used have previously been reported to alter rumen methanogen community, there were very few observed differences in the methanogen community structure detected with DGGE in the present experiment. It was concluded that this method is relatively insensitive in representing any smaller rumen methanogen shifts in response to dietary changes in these pasture based systems, possibly because these supplements did not act to eliminate methanogen groups, but to alter their activity, and this method was not suitable for assessing any changes within the diurnal period. qPCR and qRT-PCR targeting the mcrA gene were then used for highly specific quantification of methanogen quantity and gene expression. However, the available methods for extracting RNA from rumen samples were not satisfactory to yield the necessary high quality RNA from rumen samples with high quality forage diets. A highly effective method was developed by adaptation from two existing methods of Whitford et al., (1998) and Gambino et al., (2008) which could simultaneously extract RNA and DNA from the rumen samples. It was demonstrated to be highly effective for mcrA cDNA (mRNA) detection, a critical requirement for assessing activity of methanogens in this study. The applicability of this qPCR and qRT-PCR technique to quantify changes in methanogen numbers and gene expression was then tested on pen fed, ruminally fistulated cattle where the diet was allocated either once or twice daily, and rumen samples were obtained every 4h for 24h periods. mcrA gene expression, an indicator of methanogen activity, was significantly reduced (p≤0.05, t=4.90) in twice daily fed cattle, but no significant (p≤0.05) change in methanogen numbers was detected. A clear diurnal pattern of methanogen activity in forage fed cattle was established, which is the first report of its kind. This technique was then used in a cross over design experiment with ruminally fistulated cows grazing high quality pastures, and serial diurnal rumen sampling, comparing a treatment group of either an administered methanogen inhibitor or an unsupplemented control. The method detected a decrease in methanogen numbers in the treatment group after 15d of fish oil supplementation (p≤0.05, t=5.90) but the greatest effect was observed on methanogenesis activity (p≤0.05, t=7.90). There was a clear diurnal pattern of methanogen activity related to the grazing behaviour of animals, with a significant increase (p≤0.05, t=3.83) in mcrA expression observed after 8h post prandially. This understanding of diurnal methanogen activity adds significantly to the knowledge of enteric methane production, and may guide the future methane mitigation strategies using targeted supplementation strategies within the diurnal cycle to mitigate the short term production of methane in ruminants