bluuebunny/crossref_metadata_2025_split huggingface dataset:
Outcome of 100 pregnancies initiated under treatment with cabergoline in hyperprolactinaemic women
Authors: Lebbe Marie , Hubinont Corinne , Bernard Pierre , Maiter Dominique 
Published: April 2010

SummaryContext  Data concerning the safety for pregnancy of cabergoline treatment in hyperprolactinaemic women are still scarce.Objective  To exclude a higher than normal risk for miscarriage and congenital malformation in pregnancies initiated under cabergoline treatment.Design  A retrospective study of 100 pregnancies in 72 hyperprolactinaemic women treated with cabergoline at the time of conception and follow‐up of the 88 newborn children.Methods  Cabergoline was interrupted in 99 pregnancies and continued in one case. Foetal exposure dose to cabergoline was calculated for each pregnancy. Complications of pregnancy and neonatal status were compared to those observed in an age‐and delivery time‐matched control group of 163 women.Results  The mean foetal exposure dose to cabergoline was 3·6 ± 4·7 mg. The rate of spontaneous miscarriages was 10%. Three medical terminations of pregnancy were performed for a foetal malformation (3%). Minor to moderate complications were observed in 31% of the pregnancies, a figure similar to that found in the control group. An increase in tumour size (2–8 mm) was observed in 17/37 evaluated cases, needing reintroduction of cabergoline during pregnancy in five patients. The 84 deliveries resulted in 88 infants, three of them presenting with a malformation (3·4%). Neonatal status was comparable to the control group, where a malformation rate of 6·3% was observed. Postnatal development of the children was normal.Conclusion  Cabergoline treatment at the time of conception appears to be safe for both the pregnancy and the neonate, although more data are still needed on a larger number of pregnancies.
Evidence for a temperature acclimation mechanism in bacteria: an empirical test of a membrane‐mediated trade‐off
Authors: Hall Edward K. , Singer Gabriel A. , Kainz Martin J. , Lennon Jay T. 
Published: April 2010

Summary 1. Shifts in bacterial community composition along temporal and spatial temperature gradients occur in a wide range of habitats and have potentially important implications for ecosystem functioning. However, it is often challenging to empirically link an adaptation or acclimation that defines environmental niche or biogeography with a quantifiable phenotype, especially in micro‐organisms. 2. Here we evaluate a possible mechanistic explanation for shifts in bacterioplankton community composition in response to temperature by testing a previously hypothesized membrane mediated trade‐off between resource acquisition and respiratory costs. 3. We isolated two strains of Flavobacterium sp. at two temperatures (cold isolate and warm isolate) from the epilimnion of a small temperate lake in North Central Minnesota. 4. Compared with the cold isolate the warm isolate had higher growth rate, higher carrying capacity, lower lag time and lower respiration at the high temperature and lower phosphorus uptake at the low temperature. We also observed significant differences in membrane lipid composition between isolates and between environments that were consistent with adjustments necessary to maintain membrane fluidity at different temperatures. 5. Our results suggest that temperature acclimation in planktonic bacteria is, in part, a resource‐dependent membrane‐facilitated phenomenon. This study provides an explicit example of how a quantifiable phenotype can be linked through physiology to competitive ability and environmental niche.
Biogeographic synthesis of secondary succession rates in eastern North America
Authors: Wright Justin P. , Fridley Jason D. 
Published: April 2010

AbstractAim Mechanistic models of old‐field plant succession have generally lacked a broader biogeographic context in which climate, soils and species pools could play a significant role in mediating succession rates. We examine broad‐scale patterns in old‐field succession and introduce a hierarchical conceptual model to incorporate potential mechanisms operating at multiple spatial scales.Location We reviewed secondary succession studies across the Eastern Deciduous Forest (EDF) of North America.Methods We collected data from all published studies that reported the time necessary for woody species to reach either 10% or 50% cover in old‐field systems throughout the EDF. We used regression approaches to determine whether rates of succession are controlled by climatic and edaphic factors that vary at broad spatial scales.Results We found that the rate at which woody species colonize and dominate old fields decreases significantly with latitude. Rates of woody succession were highly correlated with both annual temperature (growing degree‐days for years to 10% and 50% cover) and measures of soil fertility (cation exchange capacity and reported pre‐agroindustrial (1930) maize yields for years to 10% cover), all of which show a significant latitudinal trend across the EDF.Main conclusions We suggest that the driver of this pattern is geographic variation in the intensity of competition between herbaceous and woody species, which we relate to the effects of (1) temperature regime, (2) edaphic factors related to soil fertility, and (3) plant traits, which may vary latitudinally in response to climate and edaphic factors. Although insufficient data exist to evaluate the relative importance of these factors, we argue that research in this area is necessary to gain an understanding of how future landscapes will be affected by global climate and land use change.
The use of chronosequences in studies of ecological succession and soil development
Authors: Walker Lawrence R. , Wardle David A. , Bardgett Richard D. , Clarkson Bruce D. 
Published: April 2010

Summary1. Chronosequences and associated space‐for‐time substitutions are an important and often necessary tool for studying temporal dynamics of plant communities and soil development across multiple time‐scales. However, they are often used inappropriately, leading to false conclusions about ecological patterns and processes, which has prompted recent strong criticism of the approach. Here, we evaluate when chronosequences may or may not be appropriate for studying community and ecosystem development.2. Chronosequences are appropriate to study plant succession at decadal to millennial time‐scales when there is evidence that sites of different ages are following the same trajectory. They can also be reliably used to study aspects of soil development that occur between temporally linked sites over time‐scales of centuries to millennia, sometimes independently of their application to shorter‐term plant and soil biological communities.3. Some characteristics of changing plant and soil biological communities (e.g. species richness, plant cover, vegetation structure, soil organic matter accumulation) are more likely to be related in a predictable and temporally linear manner than are other characteristics (e.g. species composition and abundance) and are therefore more reliably studied using a chronosequence approach.4. Chronosequences are most appropriate for studying communities that are following convergent successional trajectories and have low biodiversity, rapid species turnover and low frequency and severity of disturbance. Chronosequences are least suitable for studying successional trajectories that are divergent, species‐rich, highly disturbed or arrested in time because then there are often major difficulties in determining temporal linkages between stages.5. Synthesis.We conclude that, when successional trajectories exceed the life span of investigators and the experimental and observational studies that they perform, temporal change can be successfully explored through the judicious use of chronosequences.
Cancer imaging: novel concepts in clinical magnetic resonance imaging
Authors: Kwee T. C. , Takahara T. , Klomp D. W. J. , Luijten P. R. 
Published: April 2010

Abstract.  Kwee TC, Takahara T, Klomp DWJ, Luijten PR. (University Medical Center Utrecht, Utrecht, The Netherlands). Cancer imaging: novel concepts in clinical magnetic resonance imaging. J Intern Med 2010; 268: 120–132.Cancer is a major public health problem in the Western world. Imaging is of crucial importance in oncology, because it may reduce cancer‐related morbidity and mortality. To improve tumour evaluation, there is a need for functional imaging modalities that go beyond gross assessment of anatomical abnormalities and allow visualization and quantification of biochemical processes in vivo. Magnetic resonance imaging (MRI) not only provides anatomical information, but also offers a wide range of functional sequences that may aid the evaluation of cancerous lesions. Furthermore, MRI provides the opportunity to guide and monitor anticancer therapies noninvasively. The aim of this review is to highlight some of the most promising developments of MRI in the functional assessment of cancer and the guidance and monitoring of (novel) anticancer therapies.
Photometric calibration for quantitative spectral microscopy under transmitted illumination
Authors: THIGPEN J. , MERCHANT F.A. , SHAH S.K. 
Published: April 2010

SummaryOver the past decade, there have been significant developments in the mechanisms for examination of biological and material samples. These developments exploit techniques in light microscopy to elucidate specific parts of cells and tissues, as well as inorganic particles. In recent years, spectral microscopy has become more prevalent for characterization of samples. Simultaneously, sensor technology has progressed as well and modern charge‐coupled devices (CCD) cameras are now capable of achieving high spatial resolution and high sensitivity measurements of signals in the optical microscope. One major impediment in obtaining absolute quantitative information of imaged samples is the lack of automated photometric calibration mechanisms for spectral microscopes. In this paper, we present a methodology for achieving photometric calibration of an automated spectral imaging system targeted towards examination of biological samples. By acquiring spatial and spectral data simultaneously, spectral imaging allows one to exploit physical connections between a particle's morphology and its characteristic response to the optical spectrum. In composite biological material, the interpretation of the spectra is a complicated problem. This is because any light source and charge‐coupled device camera used for data acquisition does not have a uniform illumination spectra and quantum efficiency, respectively, across the emitted light spectra. To balance the spectral response across individual wavelengths, our method modulates the exposure duration for the charge‐coupled device camera during image acquisition. We present an image similarity based method to calibrate the system. Experiments to test the effectiveness of the calibration method under the various image similarity metrics are presented along with results to show the calibrated system's ability to accurately measure spectra based on the measured transmission profiles of optical filters.
The Cpx envelope stress response both facilitates and inhibits elaboration of the enteropathogenic Escherichia coli bundle‐forming pilus
Authors: Vogt Stefanie L. , Nevesinjac Anna Z. , Humphries Romney M. , Donnenberg Michael S. , Armstrong Glen D. , Raivio Tracy L. 
Published: April 2010

SummaryThe Cpx envelope stress response is induced by the misfolding of periplasmic proteins and restores envelope homeostasis by upregulating several periplasmic protein folding and degrading factors. The Cpx response also regulates the expression of a variety of envelope‐spanning protein complexes, including flagella, secretion systems and pili, which play an important role in pathogenesis. In a previous study, we inactivated the Cpx response in enteropathogenic Escherichia coli (EPEC), a causative agent of infant diarrhoea, and observed decreased expression of its major adhesin, the bundle‐forming pilus (BFP). Here, we examined the mechanism underlying this BFP expression defect, and found that this phenotype can be attributed to insufficient expression of periplasmic folding factors, such as DsbA, DegP and CpxP. Hence, a low level of Cpx pathway activity promotes BFP synthesis by upregulating factors important for folding of BFP component proteins. Conversely, we found that full induction of the Cpx response inhibits BFP expression, mainly by repressing transcription of the bfp gene cluster. In combination with a previous report examining EPEC type III secretion, our results demonstrate that the Cpx response co‐ordinates the repression of cell‐surface structures during periods of envelope stress.
Tubules and donuts: a type VI secretion story
Authors: Bönemann Gabriele , Pietrosiuk Aleksandra , Mogk Axel 
Published: April 2010

SummaryThe recently identified type VI secretion systems (T6SSs) are present in many pathogenic proteobacteria and are encoded by a conserved gene cluster. T6SSs contribute to virulence development of various pathogens and are often activated upon contact with target cells. Since the identification of the T6SS, substantial progress has been made at all levels, including gene regulation, its impact on bacterial virulence, the function of effector proteins and the mechanism of secretion. Recent structural and mechanistic studies revealed unique features of the T6SS that distinguish it from other secretion systems. Structural similarities between the T6SS‐specific exoproteins Hcp and VgrG and components of the cell‐puncturing device of tailed bacteriophages suggest that the T6SSs mimic a bacteriophage machinery to puncture target cell membranes and to translocate effector proteins, representing a novel mechanism of effector delivery. In bacteriophages contraction of the tail sheath, which engulfs the tail tube, causes ejection of the cell‐puncturing machinery. The T6SS components VipA/VipB form tubular structures, which might function as tail sheaths by engulfing Hcp proteins. The severing of VipA/VipB complexes by the AAA+ chaperone ClpV is essential for type VI protein secretion and might be linked to VipA/VipB tubule contraction, leading to the export of Hcp and VgrG.
A post‐translational, c‐di‐GMP‐dependent mechanism regulating flagellar motility
Authors: Fang Xin , Gomelsky Mark 
Published: April 2010

SummaryElevated levels of the second messenger cyclic dimeric GMP, c‐di‐GMP, promote transition of bacteria from single motile cells to surface‐attached multicellular communities. Here we describe a post‐translational mechanism by which c‐di‐GMP initiates this transition in enteric bacteria. High levels of c‐di‐GMP induce the counterclockwise bias in Escherichia coli flagellar rotation, which results in smooth swimming. Based on co‐immunoprecipitation, two‐hybrid and mutational analyses, the E. coli c‐di‐GMP receptor YcgR binds to the FliG subunit of the flagellum switch complex, and the YcgR–FliG interaction is strengthened by c‐di‐GMP. The central fragment of FliG binds to YcgR as well as to FliM, suggesting that YcgR–c‐di‐GMP biases flagellum rotation by altering FliG‐FliM interactions. The c‐di‐GMP‐induced smooth swimming promotes trapping of motile bacteria in semi‐solid media and attachment of liquid‐grown bacteria to solid surfaces, whereas c‐di‐GMP‐dependent mechanisms not involving YcgR further facilitate surface attachment. The YcgR–FliG interaction is conserved in the enteric bacteria, and the N‐terminal YcgR/PilZN domain of YcgR is required for this interaction. YcgR joins a growing list of proteins that regulate motility via the FliG subunit of the flagellum switch complex, which suggests that FliG is a common regulatory entryway that operates in parallel with the chemotaxis that utilizes the FliM‐entryway.
Reduced myoelectric activity in the sphincter of Oddi in a new model of chronic cholangitis in rabbits: an in vivo and in vitro study
Authors: Liu Y‐k. , Li Z‐h. , Liu N‐z. , He Q. , Lin H. , Wang X‐j. , Li X‐w. , Dong J‐h. 
Published: April 2010

AbstractBackground  Chronic cholangitis caused by hepatolithiasis is a common disease in Southeast Asia. Few studies have addressed the effects of chronic cholangitis on cyclic activity of the sphincter of Oddi (SO). In this study, we investigated the changes of myoelectric activity in rabbits with chronic cholangitis in vivo and in vitro.Methods  Chronic cholangitis was induced in rabbits by initially introducing three pieces of 2–0 silk suture and sequentially injecting E. coli into the choledochus through the tube in ductus cysticus. In in vivo experiments, myoelectric activity of SO was recorded by a circular electrode through the jejunum stump in conscious animals. In in vitro experiments, the SO was completely isolated and the myoelectric activity was recorded by a circular electrode in a 10‐mL organ bath filled with Krebs solution, with or without addition of cholecystokinin‐8 (CCK‐8), KCl, ionomycin or induction of capacitative calcium entry (CCE).Key Results  In comparison with control and non‐infected rabbits, the rabbits with chronic cholangitis showed higher levels of alkaline phosphatase and γ‐glutamyltransferase and significant pathological changes including increased inflammatory infiltration and collagen deposition in mucosae or muscular layer. Cyclic myoelectric activity of SO at phases 2 and 3 of migrating motor complex and the excitatory response to CCK‐8 were dramatically decreased in animals with chronic cholangitis. Myoelectric activity of SO was also significantly decreased in vitro with or without agonists or with induction of CCE.Conclusions & Inferences  Myoelectric activity of SO and its response to agonists are decreased in rabbits with chronic cholangitis both in vivo and in vitro.
Molecular mechanisms of cross‐inhibition between nicotinic acetylcholine receptors and P2X receptors in myenteric neurons and HEK‐293 cells
Authors: Decker D. A. , Galligan J. J. 
Published: April 2010

AbstractBackground  P2X2 and nicotinic acetylcholine receptors (nAChRs) mediate fast synaptic excitation in the enteric nervous system. P2X receptors and nAChRs are functionally linked. This study examined the mechanisms responsible for interactions between P2X2 and α3β4subunit‐containing nAChRs.Methods  The function of P2X2 and α3β4 nAChRs expressed by HEK‐293 cells and guinea pig ileum myenteric neurons in culture was studied using whole‐cell patch clamp techniques.Key Results  In HEK‐293 cells expressing α3β4 nAChRs and P2X2 receptors, co‐application of ATP and acetylcholine caused inward currents that were 56 ± 7% of the current that should occur if these channels functioned independently (P < 0.05, n = 9); we call this interaction cross‐inhibition. Cross‐inhibition did not occur in HEK‐293 cells expressing α3β4 nAChRs and a C‐terminal tail truncated P2X2 receptor (P2X2TR) (P > 0.05, n = 8). Intracellular application of the C‐terminal tail of the P2X2 receptor blocked nAChR‐P2X receptor cross‐inhibition in HEK‐293 cells and myenteric neurons. In the absence of ATP, P2X2 receptors constitutively inhibited nAChR currents in HEK‐293 cells expressing both receptors. Constitutive inhibition did not occur in HEK‐293 cells expressing α3β4 nAChRs transfected with P2X2TR. Currents caused by low (≤30 μmol L−1), but not high (≥100 μmol L−1) concentrations of ATP in cells expressing P2X2 receptors were inhibited by co‐expression with α3β4 nAChRs.Conclusions & Inferences  The C‐terminal tail of P2X2 receptors mediates cross‐inhibition between α3β4 nAChR‐P2X2 receptors. The closed state of P2X2 receptors and nAChRs can also cause cross‐inhibition. These interactions may modulate transmission at enteric synapses that use ATP and acetylcholine as co‐transmitters.
Sexual coevolution in the traumatically inseminating plant bug genus Coridromius
Authors: TATARNIC N. J. , CASSIS G. 
Published: April 2010

AbstractSexual conflict has recently been proposed as a driving force behind the rapid diversification of genitalia among sexually reproducing organisms. In traumatically inseminating insects, males stab females in the side of the body with needle‐like genitalia, ejaculating into their body cavity. Such mating is costly to females and has led to the evolution of cost‐reducing ‘paragenitalia’ in some species. Whereas some consider this evidence of sexually antagonistic coevolution, others remain unconvinced. Variation in the reproductive morphology of both sexes – particularly males – is alleged to be negligible, contradicting the expectations of a coevolutionary arms race. Here, we use a phylogeny of the traumatically inseminating plant bug genus Coridromius to show that external female paragenitalia have evolved multiply across the genus and are correlated with changes in male genital shape. This pattern is characteristic of an evolutionary arms race driven by sexual conflict.
Geographic variation in sperm traits reflects predation risk and natural rates of multiple paternity in the guppy
Authors: ELGEE K. E. , EVANS J. P. , RAMNARINE I. W. , RUSH S. A. , PITCHER T. E. 
Published: April 2010

AbstractGuppies (Poecilia reticulata) are models for understanding the interplay between natural and sexual selection. In particular, predation has been implicated as a major force affecting female sexual preferences, male mating tactics and the level of sperm competition. When predation is high, females typically reduce their preferences for showy males and engage more in antipredator behaviours, whereas males exploit these changes by switching from sexual displays to forced matings. These patterns are thought to account for the relatively high levels of multiple paternity in high‐predation populations compared to low‐predation populations. Here, we assess the possible evolutionary consequences of these patterns by asking whether variation in sperm traits reflect differences in predation intensity among four pairs of Trinidadian populations: four that experience relatively low levels of predation from a gape‐limited predator and four that experience relatively high levels of predation from a variety of piscivores. We found that males in high‐predation populations had faster swimming sperm with longer midpieces compared to males in low‐predation populations. However, we found no differences among males in high‐ and low‐predation populations with respect to sperm number, sperm head length, flagellum length and total sperm length.