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Two-fold Difference (two-fold + difference)
Selected AbstractsEndectocide residues affect insect attraction to dung from treated cattle: implications for toxicity testsMEDICAL AND VETERINARY ENTOMOLOGY, Issue 4 2007K. D. FLOATE Abstract A 3-year study was performed in southern Alberta, Canada to assess the effect of endectocide residues on the attractiveness of cattle dung to colonizing insects. In 2003 and 2004, insect captures were compared between pitfall traps baited with dung of untreated cattle and paired traps baited with dung of cattle that had been treated 7 days previously with topically applied doramectin, eprinomectin, ivermectin or moxidectin. Faecal residues associated with each compound affected insect captures in both spring and autumn of each year. Effects were detected (P < 0.05) for a total of 94 cases representing 27 insect taxa from 13 families in three orders (Coleoptera, Diptera, Hymenoptera). Two-fold differences in captures were common. Up to six-fold differences were observed. Eleven cases of attraction and 11 cases of repellency were associated with residues of doramectin. Eprinomectin tended to repel insects, with decreased captures for 19 of 29 cases of effect. Ivermectin showed a strong attractive effect, with increased captures for 17 of 25 cases. Moxidectin also showed a strong attractive effect, with increased captures for 17 of 18 cases. Comparisons between compounds suggested that results for doramectin best predicted results for eprinomectin and vice versa. In 2005, insect captures were compared between pitfall traps baited with dung of untreated cattle and traps baited with dung from cattle treated 3, 7 or 14 days previously with topically applied doramectin. Effects were detected in 14 cases plus one case of near significance (P= 0.053). Significant differences between control vs. days 3, 7 and/or 14 dung were detected in nine cases. Residues enhanced captures in seven of these cases. Day 14 dung affected captures in six of these cases. This study shows that endectocide residues can affect the number of insects attracted to colonize and oviposit in dung. Hence, the emergence of their offspring from field-colonized dung of untreated vs. endectocide-treated cattle should not be used as a measure of residue toxicity per se, but rather as a measure of ,insect activity'. Insect activity is a composite measure of residue toxicity, the number and species composition of insect colonists, and the mortality factors (e.g. predation, parasitism, competition) associated with the co-occurrence of these species in the dung pat. [source] A two-fold difference in the age-adjusted prevalences of Parkinson's disease between the island of Als and the Faroe IslandsEUROPEAN JOURNAL OF NEUROLOGY, Issue 6 2000L. Wermuth With the aim of comparing the previously found high prevalence of idiopathic Parkinson's disease (PD) in the Faroe Islands with the prevalence of PD in an area of Denmark, we used the same case-finding methods for case ascertainment and the same strict criteria to diagnose PD on the island of Als. During the last year before the prevalence date (1 January 1998), we found in various registries from pharmacies, hospital, private neurologist and general practioners 121 patients with suspected Parkinsonism out of 56 839 inhabitants on the island of Als. After exclusion of those who had other diseases, a total of 79 patients were left for further examinations. Among these we found 58 with PD. The overall prevalence of PD was estimated to be 102.0 and the age-adjusted prevalence to be 98.3 per 100 000 persons compared with 187.6 and 209.0 in the Faroe Islands. Compared with the previous results from the Faroe Islands (prevalence date 1 July 1995) we found an even lower mean age at onset of PD symptoms and at onset of treatment, a lower proportion of definite PD and a lower average dose of levodopa. We therefore conclude that the two-fold higher prevalence in the Faroe Islands than on the island of Als was not due to an early diagnosis and a higher ascertainment of cases with mild PD, which was suggested as being one possible explanation for our previous finding of a high prevalence of PD in the Faroe Islands. [source] Dose Range-Finding Studies With Frovatriptan in the Acute Treatment of MigraineHEADACHE, Issue 2002Alan Rapoport MD Objective.,To determine the optimum dose of frovatriptan for the acute treatment of migraine. Background.,Frovatriptan is a new triptan developed for the acute treatment of migraine. The dose-response characteristics and safety of frovatriptan have been investigated across a broad range of doses from 0.5 to 40 mg. Design.,Two randomized, placebo-controlled, double-blind, parallel-group trials, with a total of 1453 patients, were performed to determine the optimal dose of the 5-HT1B/1D agonist, frovatriptan, for the acute treatment of migraine. The dose ranges studied were 2.5 to 40 mg in the high-dose study and 0.5 to 5 mg in the low-dose study. Results.,At 2 hours postdosing for initial moderate or severe headache (International Headache Society grades 2 or 3), there was an approximate two-fold difference in the proportion of patients taking frovatriptan doses of 2.5 to 40 mg with mild or no headache compared to placebo. Frovatriptan doses of 0.5 mg and 1 mg were not more effective than placebo at 2 hours postdose, and 2.5 mg was identified as the lowest effective dose for the relief of migraine and accompanying symptoms. Above 2.5 mg, no dose-response relationship was observed for any efficacy parameters. There was an increase in the incidence of adverse events from 10 mg and above, but the vast majority were rated as mild in severity and did not impact upon tolerability in a significant manner. Conclusions.,Frovatriptan was well tolerated throughout the dose range of 0.5 to 40 mg. The 2.5-mg dose confers the optimal balance of efficacy and tolerability for the acute treatment of migraine. [source] Reproductive performance of clonal and sexual bark beetles (Coleoptera: Scolytidae) in the fieldJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2000Løyning In Ips acuminatus (Gyll.) parthenogenetic females occur together with sexual females and with sexual males upon which they depend for sperm. In a reciprocal-transplant experiment, I studied fecundity differences among parthenogenetic and sexual females from two populations that differ dramatically in the proportion of clonal females. In a second experiment, I studied competition between larvae from different mothers and between females from the two source populations. Fecundity measured by the number of eggs per egg tunnel was influenced by the ambient environment at the sites of the experiment as well as the origin of the female, and was generally higher for clonal than for sexual females at both sites. In experimental groups where larvae competed with larvae from their own population (pure treatments), the number of surviving pupae was significantly lower than in groups where females from the two source populations were mixed. The high fecundity of clonal females makes coexistence of the two types of females difficult to explain. It makes the reproductive advantage associated with clonality in I. acuminatus even higher than the two-fold difference due to asexuality per sé. The significant differences in the number of pupae in mixed vs. pure groups suggest ecological divergence between sexual and clonal females. This would make the mortality of larvae not only density dependent, but also frequency dependent, which could explain the coexistence of sexual and clonal females. [source] Sex-biased natal dispersal and inbreeding avoidance in American black bears as revealed by spatial genetic analysesMOLECULAR ECOLOGY, Issue 21 2008CECILY M. COSTELLO Abstract We tested the hypothesis that sex-biased natal dispersal reduces close inbreeding in American black bears, a solitary species that exhibits nearly complete male dispersal and female philopatry. Using microsatellite DNA and spatial data from reproductively mature bears (, 4 years old), we examined the spatial genetic structure of two distinct populations in New Mexico from 1993 to 2000. As predicted, relatedness (r) and the frequency of close relationships (parent,offspring or full siblings) decreased with distance among female dyads, but little change was observed among male or opposite-sex dyads. Neighbouring females were more closely related than neighbouring males. The potential for inbreeding was low. Most opposite-sex pairs that lived sufficiently close to facilitate mating were unrelated, and few were close relatives. We found no evidence that bears actively avoided inbreeding in their selection of mates from this nearby pool, as mean r and relationship frequencies did not differ between potential and actual mating pairs (determined by parentage analysis). These basic patterns were apparent in both study areas despite a nearly two-fold difference in density. However, the sex bias in dispersal was less pronounced in the lower-density area, based on proportions of bears with male and female relatives residing nearby. This result suggests that male bears may respond to reduced competition by decreasing their rate or distance of dispersal. Evidence supports the hypothesis that inbreeding avoidance is achieved by means of male-biased dispersal but also indicates that competition (for mates or resources) modifies dispersal patterns. [source] Strategic shotgun proteomics approach for efficient construction of an expression map of targeted protein families in hepatoma cell linesPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 12 2003Chih-Lei Lee Abstract An expression map of the most abundant proteins in human hepatoma HepG2 cells was established by a combination of complementary shotgun proteomics approaches. Two-dimensional liquid chromatography (LC)-nano electrospray ionization (ESI) tandem mass spectrometry (MS/MS) as well as one-dimensional LC-matrix-assisted laser desorption/ionization MS/MS were evaluated and shown that additional separation introduced at the peptide level was not as efficient as simple prefractionation of protein extracts in extending the range and total number of proteins identified. Direct LC-nanoESI MS/MS analyses of peptides from total solubilized fraction and the excised gel bands from one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis fractionated insolubilized fraction afforded the best combination in efficient construction of a nonredundant cell map. Compiling data from multiple variations of rapid shotgun proteomics analyses is nonetheless useful to increase sequence coverage and confidence of hits especially for those proteins identified primarily by a single or two peptide matches. While the returned hit score in general reflects the abundance of the respective proteins, it is not a reliable index for differential expression. Using another closely related hepatoma Hep3B as a comparative basis, 16 proteins with more than two-fold difference in expression level as defined by spot intensity in two-dimensional gel electrophoresis analysis were identified which notably include members of the heat shock protein (Hsp) and heterogeneous nuclear ribonucleoprotein (hnRPN) families. The observed higher expression level of hnRNP A2/B1 and Hsp90 in Hep3B led to a search for reported functional roles mediated in concert by both these multifunctional cellular chaperones. In agreement with the proposed model for telomerase and telomere bound proteins in promoting their interactions, data was obtained which demonstrated that the expression proteomics data could be correlated with longer telomeric length in tumorigenic Hep3B. This biological significance constitutes the basis for further delineation of the dynamic interactions and modifications of the two protein families and demonstrated how proteomic and biological investigation could be mutually substantiated in a productive cycle of hypothesis and pattern driven research. [source] | |||||||||||||