bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparative Assessment of the Antimicrobial Susceptibility ofStaphylococcus aureusIsolates from Bovine Mastitis in Biofilm Versus Planktonic Culture
Authors: Melchior M. B. , Fink‐Gremmels J. , Gaastra W. 
Published: August 2006

SummaryMastitis is one of the most important diseases in dairy cattle of whichStaphylococcus aureusis a major pathogen. Despite an apparently good antimicrobial susceptibilityin vitro, the cure of diseased animals from this bacteriological infection is often disappointing, which results in cases of recurrent clinical‐ and chronic subclinical infections. It has been suggested that these recurrent and chronicStaphylococcusinfections can be attributed to the growth of bacteria in biofilm. The objective of this study was to compare the susceptibility for antimicrobial agents ofS. aureusisolates obtained from bovine mastitis growing under different conditions. These conditions include a conventional conventional microbroth dilution assay in which minimal inhibitory concentration values are determined, the MBECTMassay which measures both the susceptibility in biofilm and the susceptibility of sequester cells released from the biofilm. A comparison of the susceptibility for antimicrobial agents of a number of representativeS. aureusisolates grown in broth (representingin vitrogrowth conditions) or milk (representingin vivogrowth conditions) is also made. The results indicate thatS. aureusisolates obtained from bovine mastitis are highly resistant to antimicrobial agents when growing in biofilms.
Emerging Enterohaemorrhagic Escherichia coli, Causes and Effects of the Rise of a Human Pathogen
Authors: Beutin L. 
Published: August 2006

SummaryShiga toxin (Stx) [Verotoxin (VT)]‐producing Escherichia coli (STEC), also called enterohaemorrhagic E. coli or VTEC are emerging zoonotic agents and became most important as human pathogens, particularly in the industrialized countries. Production of cytotoxins, also called Stx or VT, is the major pathogenicity determinant of STEC, which can cause life‐threatening haemorrhagic diseases in humans. The spectrum of STEC phenotypes is diverse and domestic and wildlife animals constitute important reservoirs for these bacteria. STEC are spread from animal faeces to the environment, water and food. Ingestion of contaminated foodstuff and water, as well as contact with the environment, STEC‐excreting animals or humans are the major sources of human infection. Economical changes in animal and food production, alteration of consumer habits and lack of specific immune response, particularly in urbanized populations, have contributed to the recent spread of STEC as a zoonotic agent. Supranational surveillance networks as well as national reference laboratories as sentinels play an important role in the prevention and control of STEC infections in humans. Development of new vaccines and probiotics may serve as future tools to control the spread of STEC in animals and humans.
Protective effects of EUK4010 on β‐amyloid(1–42) induced degeneration of neuronal cells
Authors: Sun Liwen , Wang Li , Sun Yong , Tang Syao‐wei , Hu Yinghe 
Published: August 2006

AbstractEUK4010 has been identified to exhibit an inhibitory effect on β‐amyloid (Aβ)1−42‐induced loss of neuronal cell viability. Further studies demonstrated that EUK4010 attenuated the Aβ1−42‐induced degeneration in both cultured rat hippocampal neurons and human neuroblastoma cells, as demonstrated by typical morphological changes, cell viability and the chip‐based flow cytometric assay. Gene expression analysis using DNA microarray showed that the senescence marker calcium‐binding protein, regucalcin (Rgn), GABA‐A receptor pi subunit (Gabrp), the huntingtin binding protein, optineurin (Optn) and a semaphorin family plexin A3 similar protein (Plex‐similar) changed their expression levels significantly in cultured neurons after Aβ1−42 treatment. In this report, we have undertaken a chemical genetic approach to study the molecular basis of Aβ1−42 effects on the neuronal degeneration. Our results demonstrate that EUK4010 completely blocked the Aβ1−42‐induced up‐regulation of GABA‐A receptor pi subunit and the semaphorin family plexin A3 similar protein, and partially attenuated the down‐regulation of senescence marker calcium‐binding protein, regucalcin. These observations suggest that EUK4010 may prevent or reduce the Aβ toxicity by regulating the expression of genes involved in the Aβ induced neuronal degeneration. These genes may represent a promising target for the therapeutic drug development for Alzheimer's disease (AD) and other neurological disorders. Furthermore, EUK4010 and its analogues could potentially be developed as neuronal protective agents for the treatment of these diseases.
The Kölliker‐Fuse nucleus gates the postinspiratory phase of the respiratory cycle to control inspiratory off‐switch and upper airway resistance in rat
Authors: Dutschmann Mathias , Herbert Horst 
Published: August 2006

AbstractLesion or pharmacological manipulation of the dorsolateral pons can transform the breathing pattern to apneusis (pathological prolonged inspiration). Apneusis reflects a disturbed inspiratory off‐switch mechanism (IOS) leading to a delayed phase transition from inspiration to expiration. Under intact conditions the IOS is irreversibly mediated via activation of postinspiratory (PI) neurons within the respiratory network. In parallel, populations of laryngeal premotoneurons manifest the IOS by a brief glottal constriction during the PI phase. We investigated effects of pontine excitation (glutamate injection) or temporary lesion after injection of a GABA‐receptor agonist (isoguvacine) on the strength of PI‐pool activity determined from respiratory motor outputs or kinesiological measurements of laryngeal resistance in a perfused brainstem preparation. Glutamate microinjections into distinct parts of the pontine Kölliker‐Fuse nucleus (KF) evoked a tonic excitation of PI‐motor activity or sustained laryngeal constriction accompanied by prolongation of the expiratory phase. Subsequent isoguvacine microinjections at the same loci abolished PI‐motor or laryngeal constrictor activity, triggered apneusis and established a variable and decreased breathing frequency. In summary, we revealed that excitation or inhibition of defined areas within the KF activated and blocked PI activity and, consequently, IOS. Therefore, we conclude, first, that descending KF inputs are essential to gate PI activity required for a proper pattern formation and phase control within the respiratory network, at least during absence of pulmonary stretch receptor activity and, secondly, that the KF contains large numbers of laryngeal PI premotor neurons that might have a key role in the regulation of upper airway resistance during reflex control and vocalization.
Action‐potential initiation and maintained activity of the isolated frog muscle spindle
Authors: Querfurth H. 
Published: August 2006

AbstractThe initiation of afferent action potentials represents the basic signalling process integrating and coding information of an external stimulus. There is also evidence in sensory receptor neurons of spontaneously generating action potentials that interfere with and modify the stimulus evoked activity. The present study investigates the generation of spontaneous action potentials in the isolated muscle spindle of the frog by recording receptor potentials, small subthreshold depolarizations, propagated impulses and interspike transients from the first Ranvier‐node of the afferent stem fibre. The temporal pattern of spontaneous discharges at resting length depended on several variables interacting at the encoding site. In the absence of mechanical stimulation, a large resting receptor potential steadily depolarized the encoding node and provoked action potentials at irregular intervals. After each action potential, the hyperpolarizing afterpotential provided a slowly increasing depolarizing interspike transient of decreasing slope (time constant 128 ms), which evoked small subthreshold depolarizations (decay time > 5 ms; multimodal amplitude distribution) before the following action potential discharged. The probability of the small subthreshold depolarizations increased the longer the resting receptor potential stayed constant at its maximum amplitude. When increasing the static prestretch level encoding depended also on the stretch‐evoked receptor potential as an additional parameter. The resulting depolarizing interspike transients were then larger and also more steeply rising, so that the afferent discharges increased in both rate and regularity. The experiments show dynamic threshold patterns that control action‐potential initiation by the assessment of the actual amplitude of depolarization and its rate of rise.
Induction of BIMEL following growth factor withdrawal is a key event in caspase‐dependent apoptosis of 661W photoreceptor cells
Authors: Gómez‐Vicente Violeta , Doonan Francesca , Donovan Maryanne , Cotter Thomas G. 
Published: August 2006

AbstractApoptosis of photoreceptor cells in the early postnatal period is a normal feature of mammalian retinal development. The role of mitochondria and caspases in the process has been well established; however, the identification of key apoptotic mediators still remains elusive. Here we report that BIMEL, a pro‐apoptotic BCL‐2 family member, may be one such molecule. Following growth factor deprivation, BIMEL was up‐regulated in mouse 661W cone photoreceptors. This event correlated with the release of mitochondrial apoptogenic factors into the cytosol, the activation of caspases and apoptosis. Moreover, a similar behaviour was observed in response to UV radiation, ionomycin or H2O2 treatments. We identified the PI3K–Akt–FKHRL1 signalling cascade as the main regulatory pathway of BIMEL expression in these cells. Finally, using RNA interference, we were able to silence BIMEL expression and subsequently suppress caspase‐3 activation. In conclusion, we propose BIMEL as a critical factor in mitochondria‐dependent apoptosis of 661W photoreceptors.
Synaptic inputs to retinal ganglion cells that set the circadian clock
Authors: Perez‐Leon Jorge Alberto , Warren Erin J. , Allen Charles N. , Robinson David W. , Lane Brown R 
Published: August 2006

AbstractMelanopsin‐containing retinal ganglion cells (RGCs) project to the suprachiasmatic nuclei (SCN) and mediate photoentrainment of the circadian system. Melanopsin is a novel retinal‐based photopigment that renders these cells intrinsically photosensitive (ip). Although genetic ablation of melanopsin abolishes the intrinsic light response, it has a surprisingly minor effect on circadian photoentrainment. This and other non‐visual responses to light are lost only when the melanopsin deficiency is coupled with mutations that disable classical rod and cone photoreceptors, suggesting that melanopsin‐containing RGCs also receive rod‐ and cone‐driven synaptic inputs. Using whole‐cell patch‐clamp recording, we demonstrate that light triggers synaptic currents in ipRGCs via activation of ionotropic glutamate and γ‐aminobutyric acid (GABA) receptors. Miniature postsynaptic currents (mPSCs) were clearly observed in ipRGCs, although they were less robust and were seen less frequently than those seen in non‐ip cells. Pharmacological treatments revealed that the majority of ipRGCs receive excitatory glutamatergic inputs that were blocked by DNQX and/or kynurenic acid, as well as inhibitory GABAergic inputs that were blocked by bicuculline. Other ipRGCs received either glutamatergic or GABAergic inputs nearly exclusively. Although strychnine (Strych)‐sensitive mPSCs were evident on many non‐ipRGCs, indicating the presence of glycinergic inputs, we saw no evidence of Strych‐sensitive events in ipRGCs. Based on these results, it is clear that SCN‐projecting RGCs can respond to light both via an intrinsic melanopsin‐based signaling cascade and via a synaptic pathway driven by classical rod and/or cone photoreceptors. It remains to be determined how the ipRGCs integrate these temporally distinct inputs to generate the signals that mediate circadian photoentrainment and other non‐visual responses to light.
The role of peripheral Na+ channels in triggering the central excitatory effects of intravenous cocaine
Authors: Brown P. Leon , Kiyatkin Eugene A. 
Published: August 2006

AbstractWhile alterations in dopamine (DA) uptake appear to be a critical mechanism underlying locomotor and reinforcing effects of cocaine (COC), many centrally mediated physiological and affective effects of this drug are resistant to DA receptor blockade and are expressed more quickly following an intravenous (i.v.) injection than expected based on the dynamics of drug concentration in the brain. Because COC is also a potent local anesthetic, its rapid action on Na+ channels may be responsible for triggering these effects. We monitored temperatures in the nucleus accumbens, temporal muscle and skin together with conventional locomotion during a single i.v. injection of COC (1 mg/kg), procaine (PRO, 5 mg/kg; equipotential anesthetic dose), a short‐acting local anesthetic drug that, like COC, interacts with Na+ channels, and cocaine methiodide (COC‐MET, 1.31 mg/kg, equimolar dose), a quaternary COC derivative that is unable to cross the blood–brain barrier. In this way, we explored not only the importance of Na+ channels in general, but also the importance of central vs. peripheral Na+ channels specifically. COC induced locomotor activation, temperature increase in the brain and muscle, and a biphasic temperature fluctuation in skin. Though PRO did not induce locomotor activation, it mimicked, to a greater degree, the temperature effects of COC. Therefore, Na+ channels appear to be a key substrate for COC‐induced temperature fluctuations in the brain and periphery. Similar to PRO, COC‐MET had minimal effects on locomotion, but mimicked COC in its ability to increase brain and muscle temperature, and induce transient skin hypothermia. It appears therefore that COC's interaction with peripherally located Na+ channels triggers its central excitatory effects manifested by brain temperature increase, thereby playing a major role in drug sensing and possibly contributing to COC reinforcement.
How parasites affect interactions between competitors and predators
Authors: Hatcher Melanie J. , Dick Jaimie T. A. , Dunn Alison M. 
Published: August 2006

AbstractWe present a synthesis of empirical and theoretical work investigating how parasites influence competitive and predatory interactions between other species. We examine the direct and indirect effects of parasitism and discuss examples of density and parasite‐induced trait‐mediated effects. Recent work reveals previously unrecognized complexity in parasite‐mediated interactions. In addition to parasite‐modified and apparent competition leading to species exclusion or enabling coexistence, parasites and predators interact in different ways to regulate or destablize the population dynamics of their joint prey. An emerging area is the impact of parasites on intraguild predation (IGP). Parasites can increase vulnerability of infected individuals to cannibalism or predation resulting in reversed species dominance in IGP hierarchies. We discuss the potential significance of parasites for community structure and biodiversity, in particular their role in promoting species exclusion or coexistence and the impact of emerging diseases. Ongoing invasions provide examples where parasites mediate native/invader interactions and play a key role in determining the outcome of invasions. We highlight the need for more quantitative data to assess the impact of parasites on communities, and the combination of theoretical and empirical studies to examine how the effects of parasitism scale up to community‐level processes.
Off‐axis symbiosis found: characterization and biogeography of bacterial symbionts of Bathymodiolus mussels from Lost City hydrothermal vents
Authors: DeChaine Eric G. , Bates Amanda E. , Shank Timothy M. , Cavanaugh Colleen M. 
Published: August 2006

SummaryOrganisms at hydrothermal vents inhabit discontinuous chemical ‘islands’ along mid‐ocean ridges, a scenario that may promote genetic divergence among populations. The 2003 discovery of mussels at the Lost City Hydrothermal Field provided a means of evaluating factors that govern the biogeography of symbiotic bacteria in the deep sea. The unusual chemical composition of vent fluids, the remote location, and paucity of characteristic vent macrofauna at the site, raised the question of whether microbial symbioses existed at the extraordinary Lost City. If so, how did symbiotic bacteria therein relate to those hosted by invertebrates at the closest known hydrothermal vents along the Mid‐Atlantic Ridge (MAR)? To answer these questions, we performed microscopic and molecular analyses on the bacteria found within the gill tissue of Bathymodiolus mussels (Mytilidae, Bathymodiolinae) that were discovered at the Lost City. Here we show that Lost City mussels harbour chemoautotrophic and methanotrophic endosymbionts simultaneously. Furthermore, populations of the chemoautotrophic symbionts from the Lost City and two sites along the MAR are genetically distinct from each other, which suggests spatial isolation of bacteria in the deep sea. These findings provide new insights into the processes that drive diversification of bacteria and evolution of symbioses at hydrothermal vents.
Surgery for local recurrence of rectal cancer
Authors: Heriot A. G. , Tekkis P. P. , Darzi A. , Mackay J. 
Published: August 2006

AbstractObjective  Despite improvement in management of primary rectal cancer, 2.6–32% of patients develop local recurrence. A proportion of these patients can be amenable to salvage surgery. The present article reviews the evidence for and against the surgical management for local recurrence of rectal cancer, the role of adjuvant and intraoperative radiotherapy (IORT), and evaluates short and long‐term outcomes.Method  A literature search was performed using Medline, Embase, Ovid and Cochrane database for studies between 1980 and 2005 assessing surgical management of local recurrence of rectal cancer and the evidence was critically evaluated.Results  Nearly 50% of rectal cancer recurrences are local and are therefore potentially amenable to curative resection. Preoperative imaging is important for appropriate selection of patients for surgery and preoperative adjuvant therapy is essential. Five‐year survival following resection ranges from 18% to 58% with 5‐year survival following complete resection of over 35% though morbidity ranges from 21% to 82%. Neoadjuvant radiotherapy is beneficial and IORT may have a contributory role in treatment. Aggressive surgical treatment favourably affects quality of life and is cost effective.Conclusion  Surgery for local recurrence can result in significant long‐term survival with acceptable morbidity and improved quality of life in appropriately selected patients. Assessment in a specialist centre familiar with these techniques is essential.
Modulation of central leptin sensitivity and energy balance in a rat model of diet‐induced obesity
Authors: Fam B. C. , Morris M. J. , Hansen M. J. , Kebede M. , Andrikopoulos S. , Proietto J. , Thorburn A. W. 
Published: August 2006

Aim:  The aim of this study was to further explore the time‐dependent changes in leptin sensitivity using a rat model of dietary fat–induced obesity and to investigate the potential mechanisms governing these changes.Methods:  We used male, adult Sprague‐Dawley rats that were fed either a standard laboratory chow diet (3% fat) or a high–saturated fat (HF) diet (60% fat) for 2 or 5 weeks. Energy balance (body weight, energy intake and energy expenditure); sensitivity to central leptin and central α‐melanin stimulating hormone (α‐MSH) administration and expression levels of hypothalamic ObRb, signal transducers and activators of transcription factor (STAT)‐3 phosphorylation, suppressor of cytokine signalling‐3 (SOCS‐3), proopiomelanocortin (POMC) processing hormones (prohormone convertase‐1 and prohormone convertase‐2) and neuropeptide Y (NPY) were measured.Results:  After 2 weeks of feeding HF diet, there was an increase in total energy intake (TEI) but a reduction in food intake as measured by the mass of food ingested. Body weight at this time was not significantly different between the two diet groups; however, white adipose tissue (WAT) weight was significantly greater in the HF‐fed rats than in the chow‐fed rats. In addition, spontaneous physical activity levels were increased, but no changes were observed in resting energy expenditure. Furthermore, chow‐fed lean rats responded to central leptin administration by reducing the energy intake by ∼67 kJ compared with saline treatment (p < 0.05), while the HF‐fed diet‐induced obese (DIO) rats responded by reducing their energy intake by ∼197 kJ compared with saline treatment (p < 0.05). After 5 weeks of feeding HF diet, TEI remained significantly higher, body weight was significantly increased by 5% in the HF‐fed rats and WAT weight was significantly heavier in HF‐fed rats than in the chow‐fed lean rats. After leptin treatment, the chow‐fed lean rats reduced their energy intake by ∼97 kJ (p < 0.05); yet, leptin had no significant effect in the HF‐fed DIO rats. ObRb protein expression, STAT‐3 phosphorylation levels, content and messenger RNA (mRNA) expression of NPY, SOCS‐3 mRNA and protein expression and energy intake response to central α‐MSH administration were not altered after HF diet feeding.Conclusion:  These results suggest that early in the course of HF diet–induced weight gain, there was a period of central leptin hypersensitivity, and as the obesity progresses, central leptin insensitivity develops. This insensitivity does not appear to be explained by a downregulation of ObRb protein levels, reduced leptin signalling, an increase in either SOCS‐3 or NPY expression or reduced function of the melanocortin system. The effect of an HF diet on other actions of leptin such as its effect on the endocannabinoid system should be investigated.
Revision of the fishfly genus Ctenochauliodes van der Weele (Megaloptera, Corydalidae)
Authors: Liu Xing Yue , Yang Ding 
Published: August 2006

The first taxonomic revision and phylogenetic analysis of the Oriental fishfly genus Ctenochauliodes van der Weele, 1909 is presented. Except for C. punctulatus, where the male is unknown, all species of Ctenochauliodes and two outgroups (Archichauliodes chilensis Kimmins and Protochauliodes bullocki Flint) were scored for 24 adult morphological characters, 21 of which were obtained from the male genitalia. The monophyly of Ctenochauliodes is corroborated by a series of synapomorphic characters. The pectinate female antenna was proposed as a diagnostic character. Two main clades within Ctenochauliodes were found based on the present phylogenetic analysis. All 12 Ctenochauliodes species are keyed, described and illustrated, with five species new to science. Ctenochauliodes forcipatus Kimmins is a junior synonym of C. friedrichi Navás, and C. moganshanus Yang & Yang is a junior synonym of C. griseus Yang & Yang. All Ctenochauliodes species were recorded from southern China, including 11 endemic species. Hence, there is no doubt that southern China should be acknowledged as the distribution centre of Ctenochauliodes.