Effect of starting stance on initial sprint performance

The effect of different starting stances from a standing position on short sprint times and the subsequent variability in times was investigated in this study. A dual-beam timing light system was used to measure 5- and 10-m times for 3 different standing starts commonly found in the sporting environment: parallel (feet parallel to the start line), split (lead left foot on start line, right leg back), and false (initial parallel start, right leg drops back to split start when movement initiated). The parallel start was found to be significantly (alpha < 0.05) slower than the other 2 stances for both the 5- ( approximately 8.3%) and the 10-m (approximately 5.9%) distances. Within the trial, variation of the different starting stances was equally consistent; however, there was less variability for the 10-m distance (CV = 1.16-1.67%) than the 5-m distance (CV = 1.43-2.15%) for each start for both men and women. The split and false start seem to offer the best option as a movement strategy for minimizing short-distance sprint times. However, the benefits of these 2 starts are less clear if total movement time is the variable of interest.     

Effects of Contact and Ingestion Exposure to Formulated CheckMate® LBAM-F and Unformulated LBAM Mating Pheromones on Adult Worker Honeybees,Apis mellifera (Hymenoptera: Apidae)

Acute 7-day toxicity tests evaluating adverse effects from contact and ingestion exposure to light brown apple moth (LBAM) pheromones and time-released microencapsulated LBAM pheromones in CheckMate® LBAM-F (Checkmate) were conducted on newly emerged honeybees (less than 24 h old). Contact studies exposed bees to 1× and 10× the CheckMate label application rate. Ingestion studies exposed bees to CheckMate formulations, and active (pheromone) ingredients (a.i.) at 0.1%, 1.0%, and 10% concentrations by weight in solid food. Bees ingested approximately 39% of their body weight during the tests. Mortality ranged from 2–10% in three of four contact and ingestion exposure trials. Trial 1, which utilized a different feeding design, showed higher mortality in both control and test replicates (9–28%). One-way ANOVA tests indicated no significant difference in mortality between control and treatment replicates in the four trials. Bees were subjected to one-time CheckMate contact exposures of up to 0.49 mg/kg-bee, and average pheromone and formulation ingestion exposures of up to 56 (0.1%), 611 (1.0%), and 6,282 (10%) mg/kg-bee-day. LBAM pheromones and microencapsulated pheromones proved to be non-toxic to honeybees when sprayed with 10× the field application rate, or when ingested in food at concentrations of up to 10% by weight.     

Phenotypic hypersusceptibility to multiple protease inhibitors and low replicative capacity in patients who are chronically infected with human immunodeficiency virus type 1

Increased susceptibility to the protease inhibitors saquinavir and amprenavir has been observed in human immunodeficiency virus type 1 (HIV-1) with specific mutations in protease (V82T and N88S). Increased susceptibility to ritonavir has also been described in some viruses from antiretroviral agent-naive patients with primary HIV-1 infection in association with combinations of amino acid changes at polymorphic sites in the protease. Many of the viruses displaying increased susceptibility to protease inhibitors also had low replication capacity. In this retrospective study, we analyze the drug susceptibility phenotype and the replication capacity of virus isolates obtained at the peaks of viremia during five consecutive structured treatment interruptions in 12 chronically HIV-1-infected patients. Ten out of 12 patients had at least one sample with protease inhibitor hypersusceptibility (change 相似文献   

A genetic algorithm approach to detecting lineage-specific variation in selection pressure

The ratio of nonsynonymous (dN) to synonymous (dS) substitution rates, omega, provides a measure of selection at the protein level. Models have been developed that allow omega to vary among lineages. However, these models require the lineages in which differential selection has acted to be specified a priori. We propose a genetic algorithm approach to assign lineages in a phylogeny to a fixed number of different classes of omega, thus allowing variable selection pressure without a priori specification of particular lineages. This approach can identify models with a better fit than a single-ratio model, and with fits that are better than (in an information theoretic sense) a fully local model, in which all lineages are assumed to evolve under different values of omega, but with far fewer parameters. By averaging over models which explain the data reasonably well, we can assess the robustness of our conclusions to uncertainty in model estimation. Our approach can also be used to compare results from models in which branch classes are specified a priori with a wide range of credible models. We illustrate our methods on primate lysozyme sequences and compare them with previous methods applied to the same data sets.     

Optimal molecular profiling of tissue and tissue components

Isolation of well-preserved pure cell populations is a prerequisite for sound studies of the molecular basis of any tissue-based biological phenomenon. This article reviews current methods for obtaining anatomically specific signals from molecules isolated from tissues, a basic requirement for productive linking of phenotype and genotype. The quality of samples isolated from tissue and used for molecular analysis is often glossed over or omitted from publications, making interpretation and replication of data difficult or impossible. Fortunately, recently developed techniques allow life scientists to better document and control the quality of samples used for a given assay, creating a foundation for improvement in this area. Tissue processing for molecular studies usually involves some or all of the following steps: tissue collection, gross dissection/identification, fixation, processing/embedding, storage/archiving, sectioning, staining, microdissection/annotation, and pure analyte labeling/identification and quantification. We provide a detailed comparison of some current tissue microdissection technologies, and provide detailed example protocols for tissue component handling upstream and downstream from microdissection. We also discuss some of the physical and chemical issues related to optimal tissue processing, and include methods specific to cytology specimens. We encourage each laboratory to use these as a starting point for optimization of their overall process of moving from collected tissue to high quality, appropriately anatomically tagged scientific results. In optimized protocols is a source of inefficiency in current life science research. Improvement in this area will significantly increase life science quality and productivity. The article is divided into introduction, materials, protocols, and notes sections. Because many protocols are covered in each of these sections, information relating to a single protocol is not contiguous. To get the greatest benefit from this article, readers are advised to read through the entire article first, identify protocols appropriate to their laboratory for each step in their workflow, and then reread entries in each section pertaining to each of these single protocols.