Home About us Contact
|
Home About us Contact | ||
|
|
||
Effects Attributable (effects + attributable)
Selected AbstractsClimate change effects on upland stream macroinvertebrates over a 25-year periodGLOBAL CHANGE BIOLOGY, Issue 5 2007ISABELLE DURANCE Abstract Climate change effects on some ecosystems are still poorly known, particularly where they interact with other climatic phenomena or stressors. We used data spanning 25 years (1981,2005) from temperate headwaters at Llyn Brianne (UK) to test three hypotheses: (1) stream macroinvertebrates vary with winter climate; (2) ecological effects attributable to directional climate change and the North Atlantic Oscillation (NAO) are distinguishable and (3) climatic effects on macroinvertebrates depend on whether streams are impacted by acidification. Positive (i.e. warmer, wetter) NAO phases were accompanied by reduced interannual stability (=similarity) in macroinvertebrate assemblage in all streams, but associated variations in composition occurred only in acid moorland. The NAO and directional climate change together explained 70% of interannual variation in temperature, but forest and moorland streams warmed respectively by 1.4 and 1.7°C (P<0.001) between 1981 and 2005 after accounting for NAO effects. Significant responses among macroinvertebrates were confined to circumneutral streams, where future thermal projections (+1, +2, +3°C) suggested considerable change. Spring macroinvertebrate abundance might decline by 21% for every 1°C rise. Although many core species could persist if temperature gain reached 3°C, 4,10 mostly scarce taxa (5,12% of the species pool) would risk local extinction. Temperature increase in Wales approaches this magnitude by the 2050s under the Hadley HadCM3 scenarios. These results support all three hypotheses and illustrate how headwater stream ecosystems are sensitive to climate change. Altered composition and abundance could affect conservation and ecological function, with the NAO compounding climate change effects during positive phases. We suggest that acidification, in impacted streams, overrides climatic effects on macroinvertebrates by simplifying assemblages and reducing richness. Climatic processes might, nevertheless, exacerbate acidification or offset biological recovery. [source] Intravenous Ethanol Infusions Can Mimic the Time Course of Breath Alcohol Concentrations Following Oral Alcohol Administration in Healthy VolunteersALCOHOLISM, Issue 5 2009Vijay A. Ramchandani Background:, Our previous studies have used intravenous (IV) clamping methods to demonstrate that family history positive (FHP) subjects exhibit a greater initial response to alcohol than family history negative (FHN) subjects. These results differ from other studies of family history of alcoholism (FHA) influences, most of which have used an oral alcohol challenge, suggesting that the route of administration may influence both the response to alcohol and FHA-related differences in response. To examine this possibility, one approach would be to directly compare responses following oral and IV alcohol administration in the same subjects. There is, however, a 3- to 4-fold variance, between- and within-subjects, in the breath alcohol concentrations (BrACs) following oral alcohol administration. Thus, our objective was to characterize the between-subject variability in the time course of BrACs following oral alcohol administration in healthy volunteers and to develop an IV infusion method to mimic the BrAC-time course attained following oral alcohol in the same subject. Methods:, This was a 2-session study in young adult, healthy, nondependent drinkers. In the first session, subjects ingested an oral dose of alcohol, based on total body water, to achieve a target peak BrAC of 80 mg%. In the second session, subjects received an IV infusion of ethanol designed to achieve the same BrAC time course as that achieved in the first session. The individualized infusion-rate profile was precomputed using a physiologically-based pharmacokinetic (PBPK) model for alcohol with model parameters adjusted to the individual's physiology. The peak BrACs (Cmax), times of peak BrAC (Tmax), and the areas under the BrAC vs. time curve (AUC) were compared between sessions to assess how closely the BrAC exposure during the IV infusion session mimicked the exposure following oral alcohol. Results:, The time course of BrACs following oral alcohol administration showed a high degree of between-subject variability. Mean Cmax, Tmax, and AUC did not differ by gender, indicating that calculation of oral doses based on total body water results in comparable BrAC-time courses, on average, for females and males. The IV infusion driven BrAC-time profiles demonstrated good fidelity to the BrAC-time curves resulting from oral alcohol: the mean %difference in Cmax and AUC were both 11%, while the mean %difference for Tmax was 27%. This degree of variability is less than half that seen across individuals following oral alcohol administration, which was substantial [coefficient of variation (%CV) ranging from 22 to 52%]. Conclusions:, Despite the use of standardized doses and controlled experimental conditions, there was substantial between-subject variability in the BrAC time course following oral administration of alcohol. The PBPK-model-based infusion method can mimic the BrACs attained with oral alcohol for individual subjects. This method provides a platform to evaluate effects attributable to the route of administration on the response to alcohol, as well as the influence of determinants such as family history of alcoholism on the alcohol response. [source] Pharmacokinetics of fentanyl delivered transdermally in healthy adult horses , variability among horses and its clinical implicationsJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 6 2006J. A. ORSINI The safety and pharmacokinetics of fentanyl, delivered transdermally at a dosage of 60,67 ,g/kg, were investigated in six healthy adult horses. Three transdermal fentanyl patches (Duragesic®), each containing 10 mg of fentanyl citrate, were applied to the mid-dorsal thorax of each horse and left in place for 72 h. Plasma fentanyl concentrations were periodically measured throughout this period and for 12 h after patch removal. After an initial delay of approximately 2 h, the plasma fentanyl concentration rose rapidly in a fairly linear fashion, reaching a peak at around 12 h; thereafter, it gradually declined in a roughly linear manner over the next 72 h. There was much individual variation, however. The initial delay ranged from 0 to 5.1 h (mean, 1.91 ± 2.0 h), Tcmax ranged from 8.5 to 14.5 h (mean, 11.4 ± 2.7 h) and Cmax ranged from 0.67 to 5.12 ng/mL (mean, 2.77 ± 1.92 ng/mL). In two horses, the plasma fentanyl concentration failed to reach even 1 ng/mL, whereas in the other four horses it was >1 ng/mL for at least 40 h and for at least 72 h in two of these horses. No adverse effects attributable to fentanyl were observed in any of the horses, indicating that this dosage is safe in systemically healthy adult horses. However, it failed to achieve plasma fentanyl concentrations generally considered to be analgesic (,1 ng/mL) in about one-third of horses. [source] College Football and Student Quality: An Advertising Effect or Culture and Tradition?AMERICAN JOURNAL OF ECONOMICS AND SOCIOLOGY, Issue 2 2009Article first published online: 9 APR 200, D. Randall Smith Intercollegiate sports are said to generate positive advertising that produces many benefits to the host school. Donations, applications, and the academic quality of the student body are some of the mission outcomes thought to rise with the fortunes of the football team. The present study tests these claims for three measures of the academic quality of the entering classes on a 12-year panel of the 233 colleges and universities competing at the highest levels of football. Results show clear positive effects attributable to the football program, though those effects are more the result of the football culture and tradition at the school than the on-field performance of the team. Any sports advertising effects of the football program are minimal when compared to the effects of nonathletic institutional characteristics on the quality of students enrolling at the school. [source] Current United Kingdom sedation practice in pediatric intensive carePEDIATRIC ANESTHESIA, Issue 7 2007IAN A. JENKINS FRCPE FRCA Summary Background:, The aim of this study was to investigate the current practice of sedation, analgesia, and neuromuscular blockade in critically ill children on pediatric intensive care units (PICUs) in the UK and identify areas that merit further study. Methods:, Data were gathered in a prospective observational study of 338 critically ill children in 20 UK PICUs. Results:, There is considerable variation in clinical practice. A total of 24 different sedative and analgesic agents were used during the study. The most commonly used sedative and analgesic agents were midazolam and morphine. Four different neuromuscular blockers (NMBs) were used, most commonly vecuronium. There were differences in treatment between cardiac and noncardiac children, but there were a greater number of infants and neonates in the cardiac group. NMBs were used in 30% of mechanically ventilated patients. Withdrawal symptoms were reported in 13% of ventilated patients, relatively early in their stay; weaning sedative agents (,tapering') was apparently of no benefit. The use of clonidine in this setting was noted. Physical restraints were used in 7.4%. Propofol was used but in only 2.6% of patients, all over the age of 4 years, and not exceeding 2 mg·kg,1·h,1. No side effects attributable to ,propofol syndrome' were noted. Conclusions:, There is considerable heterogeneity of sedation techniques. NMBs are used in a large portion of this population. Withdrawal symptoms were associated with higher doses of sedation and greater lengths of stay and were not ameliorated by withdrawing sedation gradually (,tapering'). [source] The addition of rosiglitazone to insulin in adolescents with type 1 diabetes and poor glycaemic control: a randomized-controlled trialPEDIATRIC DIABETES, Issue 4pt1 2008Monique L Stone Objective:, To evaluate the effect of rosiglitazone, an insulin sensitizer, on glycaemic control and insulin resistance in adolescents with type 1 diabetes mellitus (T1DM) Research design and methods:, Randomized, double-blind, placebo-controlled crossover trial of rosiglitazone (4 mg twice daily) vs. placebo (24 wk each, with a 4 wk washout period). Entry criteria were diabetes duration >1 yr, age 10,18 yr, puberty (,Tanner breast stage 2 or testicular volume >4 mL), insulin dose ,1.1 units/kg/day, and haemoglobin A1c (HbA1c) >8%. Responses to rosiglitazone were compared with placebo using paired t -tests. Results:, Of 36 adolescents recruited (17 males), 28 completed the trial. At baseline, age was 13.6 ± 1.8 yr, HbA1c 8.9 ± 0.96%, body mass index standard deviation scores (BMI-SDS) 0.94 ± 0.74 and insulin dose 1.5 ± 0.3 units/kg/day. Compared with placebo, rosiglitazone resulted in decreased insulin dose (5.8% decrease vs. 9.4% increase, p = 0.02), increased serum adiponectin (84.8% increase vs. 26.0% decrease, p < 0.01), increased cholesterol (+0.5 mmol/L vs. no change, p = 0.02), but no significant change in HbA1c (,0.3 vs. ,0.1, p = 0.57) or BMI-SDS (0.08 vs. 0.04, p = 0.31). Insulin sensitivity was highly variable in the seven subjects who consented to euglycaemic hyperinsulinaemic clamps. There were no major adverse effects attributable to rosiglitazone. Conclusion:, The addition of rosiglitazone to insulin did not improve HbA1c in this group of normal weight adolescents with T1DM. [source] | ||||||||||