bluuebunny/crossref_metadata_2025_split huggingface dataset:
Locating eutrophication effects across British vegetation between 1990 and 1998
Authors: Smart Simon M. , Robertson Joanne C. , Shield Eleanor J. , Van De Poll Helena M. 
Published: December 2004

AbstractLarge‐scale ecological surveillance data were analysed to determine the locations of apparent eutrophication effects across common British vegetation types between 1990 and 1998. Plant species composition was recorded from a total of 9514 fixed plots located in a stratified, random sample of 501 1 km squares across Britain. Changes in plant species composition along a gradient of substrate fertility were inferred from statistical tests of change in mean Ellenberg fertility value calculated for each fixed plot. Plots were grouped by eight vegetation types, five landscape features (hedges, road verges, watercourse banks, small biotopes, larger units in fields and unenclosed land) and six environmental zones. Tests of change in mean Ellenberg value were carried out on all combinations of these strata. Decision tree modelling was used to identify groups of test outcomes sharing the same direction of change and where each group was defined by a minimum number of strata. Post hoc power analysis was used to select statistically non‐significant test outcomes that could be used to infer stability in the sampled sub‐population.Out of a total of 142 tests of change in fertility value, 67% were increases, 8% were reductions and 25% indicated stability. The best overall predictor of increases in fertility value, and therefore of shifts in favour of plants suited to higher substrate fertility, was vegetation type. Irrespective of landscape feature and environmental zone, increased means were associated with infertile grasslands, moorland, upland woodlands and heath/bog. Already highly fertile grasslands and woodland assemblages in lowland Britain remained largely stable. The small number of decreasing test outcomes were associated with arable land in Scotland, Wales and western England. These patterns of change are hypothesized to reflect pervasive land‐use drivers combined with the inherent responsiveness of the vegetation.
Nonparametric Estimation of the Sojourn Time Distributions for a Multipath Model
Authors: Wang Weijing 
Published: December 2004

SummaryWe use a multipath (multistate) model to describe data with multiple end points. Statistical inference based on the intermediate end point is challenging because of the problems of nonidentifiability and dependent censoring. We study nonparametric estimation for the path probability and the sojourn time distributions between the states. The methodology proposed can be applied to analyse cure models which account for the competing risk of death. Asymptotic properties of the estimators proposed are derived. Simulation shows that the methods proposed have good finite sample performance. The methodology is applied to two data sets.
Hazard-Based Nonparametric Survivor Function Estimation
Authors: Prentice Ross L. , Zoe Moodie F. , Wu Jianrong 
Published: December 2004

SummaryA representation is developed that expresses the bivariate survivor function as a function of the hazard function for truncated failure time variables. This leads to a class of nonparametric survivor function estimators that avoid negative mass. The transformation from hazard function to survivor function is weakly continuous and compact differentiable, so that such properties as strong consistency, weak convergence to a Gaussian process and bootstrap applicability for a hazard function estimator are inherited by the corresponding survivor function estimator. The set of point mass assignments for a survivor function estimator is readily obtained by using a simple matrix calculation on the set of hazard rate estimators. Special cases arise from a simple empirical hazard rate estimator, and from an empirical hazard rate estimator following the redistribution of singly censored observations within strips. The latter is shown to equal van der Laan's repaired nonparametric maximum likelihood estimator, for which a Greenwood-like variance estimator is given. Simulation studies are presented to compare the moderate sample performance of various nonparametric survivor function estimators.
Chromosome number and microsporogenesis in a pentaploid accession of Brachiaria brizantha (Gramineae)
Authors: Risso‐Pascotto C. , Pagliarini M. S. , Borges do Valle C. , Mendes‐Bonato A. B. 
Published: December 2004

AbstractChromosome number, microsporogenesis and mode of reproduction are described for an accession of Brachiaria brizantha, a grass of African origin. Cytological analysis revealed that the accession BRA005886 is pentaploid (2n = 5x = 45), with a base number of x = 9. Multivalent chromosome associations, from tri‐ to pentavalents, were recorded in diakinesis, and the further meiotic behaviour was highly irregular as well. Most abnormalities were related to irregular chromosome segregation commonly found in polyploids. Micronuclei were observed following telophases I and II. Some micronuclei near the cell wall were released as microcytes, whereas others remained in the tetrad. Other meiotic abnormalities, such as cell fusion and the absence of cytokinesis causing the formation of dyads and triads were also recorded. Binucleate microspores and 2n microspores resulting from nucleus restitution were observed among the normal ones. Limitations of this accession for use in hybridization programmes are discussed.
Cyclic AMP Signalling During Mammalian Sperm Capacitation – Still Largely Terra Incognita
Authors: Harrison RAP 
Published: December 2004

ContentsCyclic AMP is known to play a major role in intracellular signalling during mammalian sperm capacitation. However, despite much research, many of the molecular details of cyclic AMP's involvement remain obscure. In this review, I discuss the following aspects, presenting some original data as illustration where relevant. With respect to cyclic AMP synthesis, uncertainties exist as to the number of forms of adenylyl cyclase that are present in the spermatozoon, whether they are cytosolic or bound to subcellular structures, and which physiological effectors they respond to (e.g. bicarbonate, Ca2+, or receptor‐coupled G‐proteins). While net intracellular levels of cyclic AMP in spermatozoa depend upon the relative activities of adenylyl cyclase and phosphodiesterase, there are wide between‐sample variations within species, both in basal levels and in levels attained after activation of the cyclase (e.g. after sperm treatment with bicarbonate). Moreover, minor changes in bulk cyclic AMP levels can result in large changes in cyclic AMP‐dependent functions. Finally, while cyclic AMP levels respond very rapidly to sperm treatment by effectors such as bicarbonate and Ca2+ (key components of capacitating media), there are big discrepancies between the rates of functional response. For example, enhancement of motility and collapse of phospholipid asymmetry take place within a few minutes, whereas more than 1 h of exposure to capacitating conditions is needed for cyclic AMP‐dependent protein tyrosine phosphorylation to become detectable or for the sperm population to attain a capacitated state.
Factors associated with improvement in breathing capacity during exercise in patients with chronic obstructive pulmonary disease
Authors: ONG Kian Chung , WANG Yee Tang 
Published: December 2004

Objectives:  The aim of this study was to explore the relationship between resting pulmonary function indices and the ratio of minute ventilation at peak exercise to the maximal voluntary ventilation (V̇Emax/MVV) and to determine whether an improvement in breathing capacity during exercise (i.e. V̇Emax/MVV > 1) is associated with greater exercise capacity in patients with COPD.Methodology:  The results of pulmonary function tests and incremental, symptom‐limited cardiopulmonary exercise testing in 84 patients with predominantly moderate to severe COPD were reviewed. Multiple linear regression analysis was applied to determine the relationship of V̇Emax/MVV with selected independent variables at rest. Multiple logistic regression was used to determine significant predictors of V̇Emax/MVV ≤ or > 1.Results:  FEV1/FVC and inspiratory capacity (IC) were the only variables among resting pulmonary function indices that were significant independent determinants of V̇Emax/MVV and the stepwise analysis generated the following equation: V̇Emax/MVV = (−1.05E−02 × FEV1/FVC) + (0.15 × IC) + 1.28; r= 0.701, P < 0.001. Using multiple logistic regression with V̇Emax/MVV ≤ or > 1 as a dependent categorical variable, FEV1/FVC was the only significant predictor among resting pulmonary indices of a V̇Emax/MVV ratio of > 1 (Odds ratio 0.93, 95%CI 0.89, 0.97). There was a significant association between V̇Emax/MVV and peak oxygen uptake (V̇O2max) after adjusting for FEV1 (r = 0.66, P < 0.001). If the categorical variable of V̇Emax/MVV (≤ or > 1) was used instead of a continuous variable, a significant association with V̇O2max remained after adjusting for FEV1 (r = 0.60, P < 0.001).Conclusions:  Among resting pulmonary function indices, the FEV1/FVC ratio is the best determinant of an improvement in breathing capacity during exercise in COPD patients. After adjusting for FEV1, an improvement in breathing capacity during exercise is associated with significantly higher exercise capacity.
Improvement in health‐related quality of life with fluticasone propionate compared with budesonide or beclomethasone dipropionate in adults with severe asthma
Authors: RUTHERFORD Carolyn , MILLS Rose , GIBSON Peter G. , PRICE Martin J. 
Published: December 2004

Objective:  Changes in health‐related quality of life (HRQoL) were evaluated in adults with severe asthma following inhaled corticosteroid treatment with high‐dose beclomethasone dipropionate or budesonide (BDP/BUD) and compared with fluticasone propionate taken at approximately half the dose of BDP/BUD.Methodology:  HRQoL was assessed as part of an open, multicentre, randomized, parallel‐group study in Australia evaluating the safety and efficacy of switching to fluticasone propionate (FP) 1000–2000 µg/day (n = 67) compared with remaining on BDP/BUD ≥1750 µg/day (n = 66) for 6 months. Patients completed two HRQoL questionnaires, the Asthma Quality of Life Questionnaire (AQLQ) and the Medical Outcomes Study Short Form‐36 (SF‐36), at baseline and at weeks 12 and 24. A change in AQLQ score of ≥0.5 was considered to be clinically meaningful.Results:  There were significant improvements in HRQoL with FP on four of the eight dimensions on the SF‐36 (i.e. physical functioning, general health, role‐emotional, and mental health), while there were no significant improvements in HRQoL in the BDP/BUD group. Overall, patients in the FP group experienced significantly greater improvement (P < 0.001) in AQLQ scores at weeks 12 and 24 compared with the BDP/BUD group. On the individual domains of the AQLQ, there were significant treatment differences (P < 0.01) in favour of FP in three of the four domains (activity limitations [0.92], symptoms [0.73], and emotional function [1.02]). Mean differences between groups for overall score and these three domains were also clinically meaningful.Conclusion:  Patients with severe asthma who received FP (at approximately half the dose of BDP/BUD) experienced statistically significant, as well as clinically meaningful, improvements in their HRQoL.
Cardiocirculatory effects of patent ductus arteriosus in extremely low‐birth‐weight infants with respiratory distress syndrome
Authors: Shimada Senji , Kasai Takeo , Hoshi Atsuki , Murata Atsushi , Chida Shoichi 
Published: December 2004

Abstract
Background
: Cardiocirculatory effects of hemodynamically significant patent ductus arteriosus (hsPDA) have not been systematically studied in extremely low‐birth‐weight (ELBW) infants with respiratory distress syndrome (RDS). The objective of the present study was to evaluate the effects of hsPDA on the left ventricular output (LVO) and organ blood flows in ELBW infants with RDS.
Methods
: Extremely low‐birth‐weight infants (birth‐weight <1000 g) treated with surfactant for RDS were studied by serial Doppler flow examinations. Doppler flow variables in 19 infants in whom hsPDA developed (hsPDA group) were compared with those in 19 infants without hsPDA matched for gestational age, birth‐weight, and postnatal age (non‐hsPDA group). All infants in the hsPDA group had pharmacologic closure of ductus arteriosus when hsPDA developed.
Results
: Before pharmacological closure of PDA, the hsPDA group had significantly higher LVO, lower blood flow volume of the abdominal aorta, and lower mean blood flow velocities in the celiac artery, superior mesenteric artery, and renal artery than the non‐hsPDA group. These alterations in the hsPDA group reverted to the levels in the non‐hsPDA group after the closure of PDA and had no deleterious effects on the cardiorespiratory status. No significant differences between the groups were found in mean blood flow velocities of the anterior cerebral artery throughout the study period.
Conclusion
: These results indicate that although LVO is increased, the splanchnic and renal blood flows are decreased when hsPDA develops in ELBW infants with RDS. The effects of these alterations of LVO and organ blood flows on the cardiorespiratory course seem to be minor when early pharmacologic closure of PDA is done.
Structural macromechanics approach in dynamics of fracture
Authors: PETROV Y. V. , MOROZOV N. F. , SMIRNOV V. I. 
Published: December 2004

ABSTRACTDiscrete features of the dynamics of fracture of solids are analyzed. The problem of modeling of some of the specific effects of brittle fracture in the high loading rate conditions is discussed. An approach based on the system of fixed material constants describing macro‐strength properties of the material is considered. New principles of material testing are analyzed. The corresponding incubation time criterion allows one to manage without the a priori given rate dependences of dynamic strength and fracture toughness. An application of the incubation time criterion to the problem of erosion is considered.
Popliteal pterygium syndrome with syngnathia
Authors: Patel Vikram , Theroux Mary C. , Reilly James 
Published: December 2004

SummaryWe report a case of perioperative management of a neonate with popliteal pterygium syndrome complicated by interalveolar syngnathia. Syngnathia were excised in the operating room without a major anaesthetic. We discuss our management of this case, as well as other possible strategies to secure the airway in neonates with syngnathia. We also reviewed the literature regarding airway management in presence of syngnathia in similar situations.
Effects of systemic and epidural morphine on antidiuretic hormone levels in children
Authors: Bozkurt Pervin , Kaya Guner , Yeker Yuksel , Altintas Fatis , Bakan Mefkur , Hacibekiroglu Munire , Kavunoglu Gulsev 
Published: December 2004

SummaryBackground: Although the use of opioids during general anaesthesia suppresses stress response to surgery and pain, the effects on antidiuretic hormone (ADH) are controversial. The aim of this study was to find the effects of morphine with either intravenous infusion or epidural route on ADH and other stress hormones.Methods: Fifty children aging (1–15 years) undergoing major genito‐urinary or abdominal operations were included in this study. The patients were allocated randomly to two groups receiving either a single dose of epidural morphine 0.1 mg·kg−1 (EP group, n = 25) postinduction or morphine infusion (INF group; n = 25) at 0.02 mg·kg−1·h−1 following 0.05 mg·kg−1 bolus. Blood samples were withdrawn for plasma ADH, osmolality, glucose, cortisol, insulin and morphine level analysis following induction and 1, 5, 12 and 24 h after initial morphine administration.Results: The two groups were similar in demographic factors, pain scores, sedation scores, and incidence of nausea and vomiting. The amount of morphine received was different between groups and the changes in serum levels of morphine were statistically significant in EP group ( P < 0.05). The changes in cortisol, blood glucose and insulin levels were insignificant in both groups (P > 0.05). The changes of ADH levels were significant at time‐points in both groups, reaching control levels at the 24th hour (P < 0.05).Conclusion: Despite the effective pain therapy and suppression of cortisol and insulin response to surgical stimulus, the increase in ADH secretion is not effected by systemic or epidural morphine administration.
The use of methohexital during chest tube removal in neonates
Authors: Allegaert K. , Naulaers G. , Debeer A. , Breysem L. , Ferens I. , Vanhole C. , Devlieger H. , Tibboel D. 
Published: December 2004

SummaryBackground : The aim of the study was the evaluation of the effect of methohexital during chest tube removal (CTR) in neonates.Methods : Evaluation was based on the degree of sedation (grades 1–4) and relaxation (grades 1–4) and trends in vital signs heart rate, mean arterial blood pressure (MAP), oxygen saturation at time points (−10, −5, −3, −1, 0, 1, 3, 5, and 10 min) before and after administration of methohexital. A multidimensional pain scale [Leuven Neonatal Pain Scale (LNPS)] was used to evaluate pain expression. Effective sedation and relaxation (grade >2) would enable the physician to perform CTR without difficulties. Paired Wilcoxon was used to compare vital signs and pain expression before and after the procedure.Results : Twenty‐two procedures in 22 infants were recorded. Eleven infants were ventilated and 21 infants were having intravenous analgesics during CTR. Birth weight was 2645 g (range 1235–4500 g). Postnatal age was 6 days (range 1–80 days). Methohexital had no effect on ventilatory weaning, MAP or oxygen saturation. Heart rate increased from 144 (49) to 162 (43) (P = 0.012) b·min−1. Sedation and relaxation were effective (>grade 2) and lasted for <5 min. No major side effects were documented. Adequate analgesia by LNPS was more difficult to evaluate as clinical pain evaluation was not feasible during full muscular relaxation.Conclusions : Administration of methohexital for CTR resulted in adequate sedation and relaxation without major side effects in neonates. This approach should be compared with other strategies.
Is licofelone, a dual inhibitor of cyclo‐oxygenase and 5‐lipoxygenase, a promising alternative in anti‐inflammatory therapy?
Authors: Bannwarth Bernard 
Published: December 2004

AbstractAs prostaglandins and leukotrienes are critical in inflammation, dual cyclo‐oxygenase and 5‐lipoxygenase enzymes inhibitors, especially licofelone, are being developed by pharmaceutical companies. Experimental data indicate that licofelone shares the antipyretic, analgesic, anti‐inflammatory and anti‐platelet activities of conventional nonsteroidal anti‐inflammatory drugs (NSAIDs), and exhibits anti‐allergic properties. Although licofelone may lead to similar adverse effects on the kidney than available NSAIDs, it appeared to induce less gastrointestinal damaging effects than nonselective NSAIDs in animals. Unfortunately, preliminary clinical studies provided less impressive data with respect to efficacy. Finally, the experimental promise of licofelone as a safe and potent anti‐inflammatory and analgesic agent remains to be proved in humans.
Influence of simulated weightlessness on the pharmacokinetics of acetaminophen administered by the oral route: a study in the rat
Authors: Gandia Peggy , Saivin Sylvie , Lavit Michel , Houin Georges 
Published: December 2004

AbstractDuring space flights, the human body is submitted to weightlessness which induces physiological variations that could modify drug disposition during space missions. Since space experiments are infrequent and difficult to perform, in order to evaluate pharmacokinetic modifications, simulation experiments of weightlessness have to be carried out on earth, using animal‐models such as the Morey‐Holton model. In this model, rats are suspended by the tail with their front paws on the ground. We studied the effects of simulated weightlessness on drug absorption and on gastric emptying, using acetaminophen as a probe. Three periods of suspension (1, 2 and 5 days) were compared with two control groups (free and attached rats). The attached group was used to evaluate a possible ‘stress effect’ caused by the suspension device. Each group was composed of 36 rats (12 sampling times and three rats per time). An oral dose of acetaminophen (100 mg/kg) was administered and blood samples were collected before and up to 12 h after administration. Plasma assays were performed using an high‐performance liquid chromatography method with UV detection. The calculated population pharmacokinetic parameters were Ka, Kel (first order absorption and elimination constants) and Vd/F (apparent volume of distribution). The statistical interpretation of the population pharmacokinetic parameters indicated that 2 days of suspension significantly decreased the Vd/F by 83% and the Ka by 125%. The increase in the Ka was probably because of an increased acceleration of the gastric emptying and/or to a decrease in the total peripheral resistance which increased intestinal blood flow.
Modulation of trigeminal reflex excitability in migraine: effects of attention and habituation on the blink reflex.
Authors: De Tommaso M , Murasecco D , Libro G , Guido M , Sciruicchio V , Specchio LM , Gallai V , Puca F 
Published: December 2004

Int J Psychophysiol. 2002 Jun;44(3):239‐249The modulation of trigeminal reflex excitability in migraine patients was evaluated during the asymptomatic phase by studying the effects of attention, habituation and preconditioning stimulus on the R2 and R3 components of the blink reflex (BR). Fifty patients suffering from migraine without aura, 20 affected by migraine with aura and 35 sex‐ and age‐matched controls were selected. In subgroups of migraine with‐aura and without‐aura patients, and normal controls, the blink reflex was elicited during different cognitive situations: (a) spontaneous mental activity; (b) stimulus anticipation; (c) recognition of target numbers. In the remaining subjects, R2 and R3 habituation was evaluated by repetitive stimulation at 1, 5, 10, 15, 20, 25 and 30 s intervals. The R2 and R3 recovery curves were also computed. A reduced R3 threshold with a normal pain threshold was found in migraine with‐aura and without‐aura patients; the R3 component was not significantly correlated with the pain thresholds in patients and controls. The R2 and R3 components were less influenced by the warning of the stimulus in migraine without‐aura and migraine with‐aura patients, in comparison with the control group. A slight increase of both R2 and R3 recovery after preconditioning stimulus was also observed in migraine patients, probably caused by a phenomenon of trigeminal hyperexcitability persisting after the last attack. The abnormal BR modulation by alerting expresses in migraine a dysfunction of adaptation capacity to environmental conditions, probably predisposing to migraine.Comment: Further physiologic and functional evidence for the interictal hyperexcitability of neurons in patients with migraine, in this case trigeminal neurons involved in the blink reflex. SJT