bluuebunny/crossref_metadata_2025_split huggingface dataset:
Length‐Dependence of Lymphatic Phasic Contractile Activity Under Isometric and Isobaric Conditions
Authors: Zhang Rongzhen , Gashev Anatoliy A. , Zawieja David C. , Lane Megan M. , Davis Michael J. 
Published: August 2007

ABSTRACTObjective: Experiments were designed to determine if the effect of preload on the spontaneous contractile activity of rat mesenteric lymphatics would be different under isometric and isobaric conditions.Methods: Isobaric protocols on cannulated, pressurized rat mesenteric lymphatics (∼ 120 μ m, ID) measured the effects of lumenal pressure on contraction amplitude, frequency, and rate of diameter change (dD/dt). Analogous protocols were conducted using a wire myograph to determine the effects of passive force (preload) on the characteristics of spontaneous, isometric force transients. Servo‐control systems allowed responses to ramp or step increases in preload/pressure to be tested.Results: Under isobaric conditions, contraction amplitude was maximal at the lowest pressure tested (1 cm H2O), and progressively declined with pressure elevation to 10 cm H2O. Changes in dD/dt followed a similar pattern. In contrast, contraction frequency progressively increased with pressure. Under isometric conditions, the amplitude of spontaneous force transients was maximal at preloads of 0.3–0.4 mN, with dF/dt following a similar pattern; the average peak amplitude was ∼ 15% of the maximal active contractile force developed during agonist stimulation. The frequency of the transients increased with preload from 0.05 to 0.3 mN, and remained constant at higher preloads. The amplitude‐frequency product, an estimate of lymphatic pumping ability, reached a maximum value at 0.4 mN in isometric vessels and at 6 cm H2O in isobaric vessels.Conclusions: Isometric and isobaric methods yielded qualitatively similar indices of spontaneous contractile activity. However, the ranges of amplitude and frequency changes were much greater under isobaric conditions (3‐ to 5‐fold) than under isometric conditions (50–80%).
The peri‐operative management of surgical insertion and removal of the intravenous oxygenator device (IVOX)
Authors: MURDOCH L. J. , BOYD O. F. , MACKAY J. , BENNETT E. D. , GROUNDS R. M. 
Published: August 2007

SummaryIntravenous oxygenation (IVOX) is a new technique for augmentation of gas exchange in patients who require near maximal conventional ventilatory support. Patients who require IVOX are, by definition, critically ill with a high expected mortality. At present, these high risk patients must be transferred to the operating theatre for the IVOX device to be inserted. This report describes the anaesthetic problems associated with nine patients in whom an IVOX device was inserted and removed in our institution. The mortality was six out of nine patients; all deaths occurred with the IVOX device in situ. Three patients died within 6 h of insertion. Four patients were female. The patients' ages ranged from 14 to 76 years. There were few immediate ventilation changes in the first 4 h after IVOX insertion. Inspired oxygenation concentration was reduced in only one patient. Positive end‐expiratory pressure was not reduced. Peak inspiratory pressure decreased in four patients. Arterial oxygen tension increased in four patients (range 0.1–2.5 kPa) and decreased in five (range 0.1–3.4 kPa). Arterial carbon dioxide tension increased in one patient (0.3 kPa) and decreased in eight (range 0.1–2.7 kPa). Inotropic support with adrenaline, dobutamine and nor adrenaline needed to be initiated or increased in eight patients. Eight patients required 2–4 units of blood to be transfused during IVOX insertion or in the following 2 h. One patient suffered an asystolic cardiac arrest during the operation, but was resuscitated successfully. Three patients survived to have the IVOX removed. There were no cardiorespiratory problems associated with its removal and although all three required a vein patch to repair the venotomy site, no patient required blood transfusion. We conclude that IVOX insertion (including transfer to and from the operating theatre) represents a significant cardiorespiratory insult to these critically ill patients. Anaesthetic staff need to be aware of the potential problems to enable them to minimise the risk of serious complications during the insertion of this novel device.
Effects of thiopentone, etomidate and propofol on beat‐to‐beat cardiovascular signals in man
Authors: SCHEFFER G. J. , TEN VOORDE B. J. , KAREMAKER J. M. , ROS H. H. , DE LANGE J. J. 
Published: August 2007

SummaryAnalysis of beat‐to‐beat fluctuations of heart rate and blood pressure is a promising new approach to the clinical diagnosis and management of alterations in cardiovascular regulation. We investigated the effects of three induction agents on beat‐to‐beat heart rate and blood pressure fluctuations in man. Beat‐to‐beat fluctuations were analysed by spectral analysis. Two spectral areas are of main interest. One area is centred on the respiratory frequency and shifts with changes in respiratory rate (High Frequency area). These high frequency flucuations in heart rate are caused by respiratory‐induced blood pressure fluctuations, mediated by the vagus nerve through the baroreflex mechanism. Variability in the Low Frequency area, which occurs between 0.06 and 0.12 Hz is considered to be related to haemodynamic fluctuations due to the sympathetic baroreflex control loop of vasomotor activity and heart rate. Results from our study indicate that thiopentone, etomidate and propofol show considerable differences in their effects on beat‐to‐beat variability of heart rate and blood pressure. These differences can be explained by their specific effects on the cardiovascular system.
Drug‐induced hyperthermia
Authors: NIMMO S. M. , KENNEDY B. W. , TULLETT W. M. , BLYTH A. S. , DOUGALL J. R. 
Published: August 2007

SummaryDrugs with antidopaminergic properties and those capable of stimulating serotonin release can be responsible for hyperthermia syndromes such as neuroleptic malignant syndrome and serotonin syndrome. Dopamine and serotonin are important neurotransmitters in temperature regulation and it is likely that these reactions result from drug‐induced changes in neurotransmitter levels. We describe three cases of drug‐induced hyperthermia, discuss their aetiology and management, with both general measures and therapies designed to redress neurotransmitter imbalance.
A technique of awake fibreoptic intubation
Authors: Sldhu V.S. , Whltehead E.M. , Ainsworth Q.P. , Smith M. , Calder I. 
Published: August 2007

SummaryWe report our experience of 58 patients undergoing awake fibreoptic intubation for cervical spine surgery. Topical anaesthesia was administered using a ‘spray as you go’ technique. The tracheas of 57 patients were intubated successfully. The mean time from starting topical anaesthesia to intubation was 16. l min (SEM 1.0). The procedure was associated with cardiovascular stability, a low incidence of severe cough and had a high patient acceptance. There was a low failure rate amongst trainees. The minimum mean arterial oxygen saturation was 92.9% (SEM 1.1). There was no relationship between the time taken to intubation and the episodes of desaturation or the grade oflaryngeal visibility at direct laryngoscopy. This method of producing topical anaesthesia for awake fibreoptic intubation is recommended.
Dynamics of soil organic matter turnover and soil respired CO2 in a temperate grassland labelled with 13C
Authors: Theis D. E. , Jaeggi M. , Aeschlimann D. , Blum H. , Frossard E. , Siegwolf R. T. W. 
Published: August 2007

SummaryThe fate of carbon (C) in grassland soils is of particular interest since the vast majority in grassland ecosystems is stored below ground and respiratory C‐release from soils is a major component of the global C balance. The use of 13C‐depleted CO2 in a 10‐year free‐air carbon dioxide enrichment (FACE) experiment, gave a unique opportunity to study the turnover of the C sequestered during this experiment. Soil organic matter (SOM), soil air and plant material were analysed for δ13C and C contents in the last year of the FACE experiment (2002) and in the two following growing seasons. After 10 years of exposure to CO2 enrichment at 600 ppmv, no significant differences in SOM C content could be detected between fumigated and non‐fumigated plots. A 13C depletion of 3.4‰ was found in SOM (0–12 cm) of the fumigated soils in comparison with the control soils and a rapid decrease of this difference was observed after the end of fumigation. Within 2 years, 49% of the C in this SOM (0–12 cm) was exchanged with fresh C, with the limitation that this exchange cannot be further dissected into respiratory decay of old C and freshly sequestered new C. By analysing the mechanistic effects of a drought on the plant‐soil system it was shown that rhizosphere respiration is the dominant factor in soil respiration. Consideration of ecophysiological factors that drive plant activity is therefore important when soil respiration is to be investigated or modelled.
Conservation tillage on loamy soils: explaining the variability in interrill runoff and erosion reduction
Authors: Leys A. , Govers G. , Gillijns K. , Poesen J. 
Published: August 2007

SummaryPrevious studies have shown that runoff generation on conventionally tilled fields on loamy soils is primarily controlled by soil surface characteristics. In this study we investigate the factors controlling runoff generation and interrill erosion on fields under reduced and no‐tillage in central Belgium. Over a period of 5 years, 184 rainfall simulation experiments on small‐scale plots (∼0.73 m2) were conducted on fields planted with maize and sugar beet. The results clearly confirmed the beneficial effects of reduced tillage in terms of runoff and soil loss, with a reduction in 63 and 88% of the cases, respectively, but they also indicated that the effect of the application of conservation tillage was highly variable. The erosion‐reducing effect of conservation tillage was more pronounced when large absolute soil loss rates on the conventionally‐tilled part were recorded. Empirical regression models are proposed to explain observed variations. Overall, factors relating to the surface state of the soil, such as crusting and total cover, appear to be much more important in controlling runoff than intrinsic soil characteristics, such as organic matter content and texture. Thus, soil surface characteristics control runoff generation on loamy soils, also when conservation tillage is applied. Whereas a single empirical model for the description of the runoff response could be used for all the tillage techniques, separate relationships for each tillage technique were required for soil loss.
Do surface active substances from water repellent soils aid wetting?
Authors: Graber E. R. , Tagger S. , Wallach R. 
Published: August 2007

SummarySoil water repellency is usually unstable, as exemplified by the common method of quantifying repellency degree – the water drop penetration time (WDPT) test. Dynamic penetration and infiltration of water into repellent soils is generally attributed to either reduction of the solid‐liquid interfacial energy (γSL) or reduction of the liquid‐vapour interfacial energy (γLV), or both. The reduction of γSL can result from conformation changes, hydration, or rearrangement of organic molecules coating soil particle surfaces as a result of contact with water, while the reduction of γLV can result from dissolution of soil‐borne surface active organic compounds into the water drop. The purpose of this study was to explicitly test the role of the second mechanism in dynamic wetting processes in unstably repellent soils, by examining the drop penetration time (DPT) of water extracts from repellent soils obtained after varying extraction times and at different soil : water ratios. It was indeed found that soil extracts had lower surface tensions (γLV approx. 51–54 mN m−1) than distilled water. However, DPT of the soil extracts in water repellent soils was generally the same or greater than that of water. Salt solutions with the same electrical conductivity and monovalent/divalent cation ratio as the soil extracts, but lacking surface active organic substances, had the same DPT as did the extracts. In contrast, DPT of ethanol solutions prepared with the same γLV, electrical conductivity, and monovalent/divalent cation ratio as the soil extracts, was much faster. Ethanol solutions are usually used as an agent to reduce γLV and as such, to reduce DPT. It is concluded that the surface‐active, soil‐derived organic substances in aqueous soil extracts do not contribute to wetting dynamics, and as such, this mechanism for explaining kinetics of water penetration into water repellent soils is rejected. It is also concluded that the rapid penetration of ethanol solutions must be due not only to changes in γLV, but to also to changes in either or both γSL and the solid‐vapour interfacial energy (γSV). These results stand in sharp contrast to well‐accepted logical paradigms.
Estimation of Linear Models of Coregionalization by Residual Maximum Likelihood
Authors: Marchant B. P. , Lark R. M. 
Published: August 2007

SummaryObservations of ancillary soil properties spatially correlated to a soil property of interest may be used to increase the precision and reduce the sampling costs of a geostatistical survey. The relationship between such coregionalized properties must be expressed as a linear model of coregionalization but the conventional estimator of the linear model of coregionalization is biased unless the mean value of each property is constant across the study region. However, the mean value of a soil property may vary according to a spatial trend or a deterministic relationship with other factors which vary within the study region. We therefore propose that a linear mixed model should be fitted to coregionalized soil properties by residual maximum likelihood. This approach simultaneously fits spatial trends or deterministic relationships and random effects to the observations with minimum bias. We implement a residual maximum likelihood estimator for coregionalized properties and suggest a criterion to decide what order of spatial trend and which deterministic relationships should be included in the model. The effectiveness of the estimator is proved upon simulated data and upon observations of zinc and cadmium concentrations from the Swiss Jura.
Short‐term climatic trends affect the temporal variability of macroinvertebrates in California ‘Mediterranean’ streams
Authors: BÊCHE LEAH A. , RESH VINCENT H. 
Published: August 2007

Summary1. Long‐term studies in ecology are essential for understanding natural variability and in interpreting responses to disturbances and human perturbations. We assessed the long‐term variability, stability and persistence of macroinvertebrate communities by analysing data from three regions in northern California with a mediterranean‐climate. During the study period, precipitation either increased or decreased, and extreme drought events occurred in each region.2. Temporal trends in precipitation resulted in shifts from ‘dry‐year’ communities, dominated by taxa adapted to no or low flow, to ‘wet‐year’ communities dominated by taxa adapted to high flows. The abundance of chironomid larvae was an important driver of community change. Directional change in community composition occurred at all sites and was correlated with precipitation patterns, with more dramatic change occurring in smaller streams.3. All communities exhibited high to moderate persistence (defined by the presence/absence of a species) and moderate to low stability (defined by changes in abundance) over the study period. Stability and persistence were correlated with climatic variation (precipitation and El Niño Southern Oscillation) and stream size. Stability and persistence increased as a result of drought in small streams (first‐order) but decreased in larger streams (second‐ and third‐order). Communities from the dry season were less stable than those from the wet‐season.4. This study demonstrates the importance of long‐term studies in capturing the effects of and recovery from rare events, such as the prolonged and extreme droughts considered here.
Cross‐species transferability of microsatellite markers from six aphid (Hemiptera: Aphididae) species and their use for evaluating biotypic diversity in two cereal aphids
Authors: Weng Y. , Azhaguvel P. , Michels G. J. , Rudd J. C. 
Published: August 2007

AbstractThe abundance and distribution of microsatellites, or simple sequence repeats (SSRs) were explored in the expressed sequence tag (EST) and genomic sequences of the pea aphid, Acyrthosiphon pisum (Harris), and the green peach aphid, Myzus persicae (Sulzer). A total of 108 newly developed, together with 40 published, SSR markers were investigated for their cross‐species transferability among six aphid species. Genetic diversity among six greenbug, Schizaphis graminum (Rondani) and two Russian wheat aphid, Diuraphis noxia (Kurdjumov) biotypes was further examined with 67 transferable SSRs. It was found that the pea aphid genome is abundant in SSRs with a unique frequency and distribution of SSR motifs. Cross‐species transferability of EST‐derived SSRs is dependent on phylogenetic closeness between SSR donor and target species, but is higher than that of genomic SSRs. Neighbor‐joining analysis of SSR data revealed host‐adapted genetic divergence as well as regional differentiation of greenbug biotypes. The two Russian wheat aphid biotypes are genetically as diverse as the greenbug ones although it was introduced into the USA only 20 years ago. This is the first report of large‐scale development of SSR markers in aphids, which are expected to have wide applications in aphid genetic, ecological and evolutionary studies.
Regulation of Junonia coenia densovirus P9 promoter expression
Authors: Shirk P. D. , Bossin H. , Furlong R. B. , Gillett J. L. 
Published: August 2007

AbstractTranscriptional activity of the Junonia coenia densovirus (JcDNV) P9 promoter depends on a 557‐bp sequence located within the overlapping 3′ sequences for viral capsid and nonstructural genes. Utilizing a somatic transformation assay to assess JcDNV promoter activity in Drosophila melanogaster and Plodia interpunctella, viral sequences were subjected to deletional analysis. Removal of a 685‐bp fragment reduced P9‐driven expression to background levels. Inclusion of a second expression cassette demonstrated vector persistence and confirmed somatic transformation. P9 promoter‐driven expression was restored by insertion of a 557‐bp JcDNV fragment or by inclusion of a heterologous baculovirus hr5 enhancer. Consensus polycomb transcriptional factor binding sites were identified within the 557‐bp fragment, which suggests a potential role in regulating densoviral transcription.
Living with early‐stage dementia: the perspective of older Chinese people
Authors: Mok Esther , Lai Claudia K.Y. , Wong Fanny L.F. , Wan Pauline 
Published: August 2007

AbstractTitle.  Living with early‐stage dementia: the perspective of older Chinese people Aim.  This paper is a report of a study to describe the lived experiences of people with early‐stage dementia and their ways of coping with the illness.Background.  Emerging models of subjective experience and coping with early dementia have been developed in Western cultures. Understanding how Chinese people with early‐stage dementia adjust and cope is an important starting point in developing interventions that can enhance their adaptive coping.Method.  A convenience sample of 15 Chinese people in the early stages of dementia were interviewed and observed during home visits. The study involved in‐depth transcribed interview data using a phenomenological approach. The data were collected in 2005.Results.  Four themes were identified in the data: attribution of illness, experiencing losses resulting in frustration and uncertainty, adapting to a new role in relationships with family and friends and continuing to live. People with early dementia who adopted a positive outlook did so because they had made sense of and accepted the illness, received understanding and support from family and friends and were being listened to and respected.Conclusion.  The themes emerging from the findings could be used as a framework in understanding how people cope with the onset of early dementia. The framework includes specific implications for the provision of intervention services and highlights the importance of understanding people’s own constructions of their illness and how they adjust their lives in coping.
Plasmid partition and incompatibility – the focus shifts
Authors: Bouet Jean‐Yves , Nordström Kurt , Lane David 
Published: August 2007

SummaryThe mitotic apparatus that a plasmid uses to ensure its stable inheritance responds to the appearance of an additional copy of the plasmid's centromere by segregating it from the pre‐existing copies: if the new copy arises by replication of the plasmid the result is partition, if it arrives on a different plasmid the result is incompatibility. Incompatibility thus serves as a probe of the partition mechanism. Coupling of distinct plasmids via their shared centromeres to form mixed pairs has been the favoured explanation for centromere‐based incompatibility, because it supports a long‐standing assumption that pairing of plasmid replicas is a prerequisite for their partition into daughter cells. Recent results from molecular genetic and fluorescence microscopy studies challenge this mixed pairing model. Partition incompatibility is seen to result from various processes, including titration, randomized positioning and a form of mixed pairing that is based on co‐activation of the same partition event rather than direct contact between partition complexes. The perspectives thus opened onto the partition mechanism confirm the continuing utility of incompatibility as an approach to understanding bacterial mitosis. The results considered are compatible with the view that direct pairing of plasmids is not essential to plasmid partition.
Identification of an α(1→6) mannopyranosyltransferase (MptA), involved in Corynebacterium glutamicum lipomanann biosynthesis, and identification of its orthologue in Mycobacterium tuberculosis
Authors: Mishra Arun K. , Alderwick Luke J. , Rittmann Doris , Tatituri Raju V. V. , Nigou Jerome , Gilleron Martine , Eggeling Lothar , Besra Gurdyal S. 
Published: August 2007

Summary Corynebacterium glutamicum and Mycobacterium tuberculosis share a similar cell wall architecture, and the availability of their genome sequences has enabled the utilization of C. glutamicum as a model for the identification and study of, otherwise essential, mycobacterial genes involved in lipomannan (LM) and lipoarabinomannan (LAM) biosynthesis. We selected the putative glycosyltransferase‐Rv2174 from M. tuberculosis and deleted its orthologue NCgl2093 from C. glutamicum. This resulted in the formation of a novel truncated lipomannan (Cg‐t‐LM) and a complete ablation of LM/LAM biosynthesis. Purification and characterization of Cg‐t‐LM revealed an overall decrease in molecular mass, a reduction of α(1→6) and α(1→2) glycosidic linkages illustrating a reduced degree of branching compared with wild‐type LM. The deletion mutant's biochemical phenotype was fully complemented by either NCgl2093 or Rv2174. Furthermore, the use of a synthetic neoglycolipid acceptor in an in vitro cell‐free assay utilizing the sugar donor β‐d‐mannopyranosyl‐1‐monophosphoryl‐decaprenol together with the neoglycolipid acceptor α‐d‐Manp‐(1→6)‐α‐d‐Manp‐O‐C8 as a substrate, confirmed NCgl2093 and Rv2174 as an α(1→6) mannopyranosyltransferase (MptA), involved in the latter stages of the biosynthesis of the α(1→6) mannan core of LM. Altogether, these studies have identified a new mannosyltransferase, MptA, and they shed further light on the biosynthesis of LM/LAM in Corynebacterianeae.