bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporal pattern of plasma membrane calcium ATPase 2 expression in the spinal cord correlates with the course of clinical symptoms in two rodent models of autoimmune encephalomyelitis
Authors: Nicot Arnaud , Kurnellas Michael , Elkabes Stella
Published: May 2005

Axonal/neuronal pathology is an important and early feature of multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE). However, the underlying molecular mechanisms remain elusive. We have previously reported that the levels of an important neuronal calcium pump, plasma membrane calcium ATPase 2 and synaptic proteins, synapsin IIa and syntaxin 1B are decreased in the rat spinal cord at onset of acute EAE. Whether the expression of these genes is restored during neurological recovery and affected in other EAE models is currently unknown. The present study was undertaken to address these issues by use of validated multiplex quantitative real‐time RT‐PCR with fluoro‐primers, western blot and immunocytochemistry. We report that plasma membrane calcium ATPase 2 (PMCA2) transcript and protein levels return to control values during recovery from acute disease in the Lewis rat, whereas they are reduced throughout the course of chronic, non‐remitting EAE in the C57Bl/6 mouse. These results indicate a close correlation between PMCA2 levels and disease course as defined by clinical scores reflecting motor deficits. Decrease in synapsin IIa expression also correlated with the onset and progression of neurological symptoms, whereas the pattern of syntaxin 1B mRNA and protein expression suggested post‐transcriptional regulation. The decrease in PMCA2 transcript and protein levels and the correlation between expression and disease course in two different EAE models further highlight the importance of this calcium pump in neuronal dysfunction during inflammation.
Role of the glycine site of the N‐methyl‐d‐aspartate receptor in synaptic plasticity induced by pairing
Authors: Krasteniakov N. V. , Martina M. , Bergeron R.
Published: May 2005

In the hippocampal CA1 region of the rat, activity‐dependent plasticity requires substantial postsynaptic depolarization and activation of the N‐methyl‐d‐aspartate glutamate receptor subtype (NMDAR). Exogenous and endogenous compounds selectively modulate NMDAR function by acting at the glycine coagonist site. Here we investigate the modulatory role of the glycine site in the induction of bidirectional synaptic plasticity. Plasticity was induced by pairing low‐frequency afferent pulses with different levels of postsynaptic depolarization in the absence and presence of glycine site compounds. We found strong dependence of glycine site agonist modulation on membrane voltage during induction. Thus, d‐serine and glycine were more effective in enhancing long‐term potentiation (LTP) during pairing of small depolarization (−60 or −50 mV) with subthreshold EPSCs than during pairing of stronger depolarization (−40 mV) with suprathreshold synaptic responses. The glycine site role in bidirectional synaptic plasticity was studied with the selective antagonist 7‐chlorokynurenic acid. Blockade of the glycine site during the pairing reversed the direction of plasticity from LTP towards long‐term depression. The magnitude of depression was dependent on antagonist concentration and the level of depolarization during the pairing. Thus, these experiments demonstrate the role of the glycine site in the induction of bidirectional synaptic plasticity.
Persistent alterations in neuropeptide Y release in the paraventricular nucleus of rats subjected to dietary manipulation during early life
Authors: Kozak R. , Richy S. , Beck B.
Published: May 2005

The aim of the present experiment was to determine the influence of nutritional manipulations during early life on feeding regulatory mechanisms. For this purpose, neuropeptide Y (NPY) release in the hypothalamic paraventricular nucleus was measured in male offspring born to dams fed either on a control (C) diet, on a high‐carbohydrate (HC) diet or on a high‐fat (HF) diet during gestation and lactation periods. In addition, we examined the development of dietary preferences in these rats. NPY release was measured in vivo through the push–pull technique after a stimulation with 2‐deoxy‐glucose (2DG), a blocker of carbohydrate metabolism. NPY release was significantly enhanced in the HC rats after 2DG (+89% vs. control and +54% vs. HF rats; P < 0.01). In a two‐bottle choice test, a clear preference for carbohydrate (62% vs. 38%; P < 0.01) was present as early as 30 days of age in control rats. The establishment of this preference in HC and HF rats was delayed by 2 and 3 months, respectively. Therefore, each type of dietary manipulation during early life has left a specific imprint in the offspring. The change in reactivity of the NPY system to glucopenia persisted in adulthood. When combined with the early changes in the dietary preferences, this can lead to adverse effects on body weight when abundant and palatable food is offered. These data support the hypothesis of an intrauterine and perinatal programming of the central regulatory mechanisms and reinforce the necessity of a preventive approach for the treatment of obesity and related metabolic disorders.
Forebrain patterns of c‐Fos and FosB induction during cancer‐associated anorexia–cachexia in rat
Authors: Konsman Jan Pieter , Blomqvist Anders
Published: May 2005

Forebrain structures are necessary for the initiation of food intake and its coupling to energy expenditure. The cancer‐related anorexia–cachexia syndrome is typified by a prolonged increase in metabolic rate resulting in body weight loss which, paradoxically, is accompanied by reduced food intake. The aim of the present work was to study the forebrain expression of Fos proteins as activation markers and thus to identify potential neurobiological mechanisms favouring catabolic processes or modulating food intake in rats suffering from cancer‐related anorexia–cachexia. Neurons in forebrain structures showing most pronounced induction of Fos proteins were further identified neurochemically. To provoke anorexia–cachexia, cultured Morris hepatoma 7777 cells were injected subcutaneously in Buffalo rats. This resulted in a slowly growing tumour inducing ≈ 7% body weight loss and a 20% reduction in food intake when the tumour represented 1–2% of body mass. Anorexia‐cachexia in these animals was found to be accompanied by Fos induction in several hypothalamic nuclei including the paraventricular and ventromedial hypothalamus, in the parastrial nucleus, the amygdala, the bed nucleus of the stria terminalis, ventral striatal structures and the piriform and somatosensory cortices. Neurochemical identification revealed that the vast majority of FosB‐positive neurons in the nucleus accumbens, ventral caudate–putamen and other ventral striatal structures contained prodynorphin or proenkephalin mRNA. These findings indicate that forebrain structures that are part of neuronal networks modulating catabolic pathways and food ingestion are activated during tumour‐associated anorexia–cachexia and may contribute to the lack of compensatory eating in response to weight loss characterizing this syndrome.
Intercollicular commissural projections modulate neuronal responses in the inferior colliculus
Authors: Malmierca Manuel S. , Hernández Olga , Rees Adrian
Published: May 2005

The right and left inferior colliculi (ICs) in the auditory midbrain are connected to one another by a bundle of fibres, the commissure of the IC. Previous studies show that this commissural projection connects corresponding frequency regions in the two sides and originates mainly from excitatory neurons, although some studies suggest a smaller number of GABAergic inhibitory neurons may also project via the commissure. Although the commissure of the IC is a major pathway connecting the most important nuclei of the auditory tectum, little is known about its functional significance. To investigate its role in auditory processing in the rat, we recorded sound‐evoked responses of single neurons in one IC while injecting kynurenic acid into a corresponding region of the opposite IC. This procedure enabled us to block reversibly excitation of commissural projections to the recorded IC. The changes in the neural responses when input from the opposite IC was blocked are consistent with the commissural projection exerting both an excitatory and an inhibitory influence. The inhibition could be accounted for by monosynaptic or disynaptic connections. The responses to both monaural and binaural stimulation were affected, and the effects were proportionately greater at near‐threshold sound levels. The results suggest that one function of the commissure of the IC may be to modulate the response gain of IC neurons to acoustic stimulation.
Orexin and MCH neurons express c‐Fos differently after sleep deprivation vs. recovery and bear different adrenergic receptors
Authors: Modirrousta Mandana , Mainville Lynda , Jones Barbara E.
Published: May 2005

Though overlapping in distribution within the posterior hypothalamus, neurons containing orexin (Orx) and melanin concentrating hormone (MCH) may play different roles in the regulation of behavioural state. In the present study in rats, we tested whether they express c‐Fos differently after total sleep deprivation (SD) vs. sleep recovery (SR). Whereas c‐Fos expression was increased in Orx neurons after SD, it was increased in MCH neurons after SR. We reasoned that Orx and MCH neurons could be differently modulated by noradrenaline (NA) and accordingly bear different adrenergic receptors (ARs). Of all Orx neurons (estimated at ≈6700), substantial numbers were immunostained for the α1A‐AR, including cells expressing c‐Fos after SD. Yet, substantial numbers were also immunostained for the α2A‐AR, also including cells expressing c‐Fos after SD. Of all MCH neurons (estimated at ≈12 300), rare neurons were immunostained for the α1A‐AR, whereas significant numbers were immunostained for the α2A‐AR, including cells expressing c‐Fos after SR. We conclude that Orx neurons may act to sustain waking during sleep deprivation, whereas MCH neurons may act to promote sleep following sustained waking. Some Orx neurons would participate in the maintenance of waking during deprivation when excited by NA through α1‐ARs, whereas MCH neurons would participate in sleep recovery after deprivation when released from inhibition by NA through α2‐ARs. On the other hand, under certain conditions, Orx neurons may also be submitted to an inhibitory influence by NA through α2‐ARs.
Specificity of regions processing biological motion
Authors: Peuskens H. , Vanrie J. , Verfaillie K. , Orban G. A.
Published: May 2005

Using functional magnetic resonance imaging and point light displays portraying six different human actions, we were able to show that several visual cortical regions, including human MT/V5 complex, posterior inferior temporal gyrus and superior temporal sulcus, are differentially active in the subtraction comparing biological motion to scrambled motion. Comparison of biological motion to three‐dimensional rotation (of a human figure), articulated motion and translation suggests that human superior temporal sulcus activity reflects the action portrayed in the biological motion stimuli, whereas posterior inferior temporal gyrus responds to the figure and hMT/V5+ to the complex motion pattern present in biological motion stimuli. These results were confirmed with implied action stimuli.
Phosphatidyl‐inositide signalling proteins in a novel class of sensory cells in the mammalian olfactory epithelium
Authors: Elsaesser Rebecca , Montani Giorgia , Tirindelli Roberto , Paysan Jacques
Published: May 2005

Ciliated sensory neurons, supporting cells and basal stem cells represent major cellular components of the main olfactory epithelium in mammals. Here we describe a novel class of sensory cells in the olfactory neuroepithelium. The cells express phospholipase C beta‐2 (PLC β2), transient receptor potential channels 6 (TRPC6) and inositol 3, 4, 5‐trisphosphate receptors type III (InsP3R‐III). Unlike ciliated olfactory neurons, they express neither olfactory marker protein nor centrin, adenylyl cyclase or cyclic nucleotide‐gated cation channels. Typical components of the cytoskeleton of microvilli, ezrin and actin are found co‐localized with PLC β2 and TRPC6 in apical protrusions of the cells. In Ca2+‐imaging experiments, the cells responded to odours. They express neuronal marker proteins and possess an axon‐like process, but following bulbectomy the cells do not degenerate. Our results suggest a novel class of microvillous secondary chemosensory cells in the mammalian olfactory system. These cells, which utilize phosphatidyl‐inositides in signal transduction, represent about 5% of all olfactory cells. Their abundance indicates that they play an important role in stimulus‐dependent functions and/or the regeneration of the olfactory system.
Transient, powerful pressures are generated in the brain by a rotational acceleration impulse to the head
Authors: Krave Ulrika , Höjer Svante , Hansson Hans‐Arne
Published: May 2005

A rotational acceleration impulse to a head, as occurs at traffic accidents, sport injuries, assaults and falls, induces a diffuse brain damage that eventually could result in persistent neuropsychiatric deficits and neurodegeneration. Emphasis has been concentrated on the relative motion of the brain inside the skull during head impact, whereas less attention has been paid to whether intracranial pressure changes are generated and, if so, the implications thereof. In the present experimental study we investigated in an animal model system, based on rabbits, if a sagittal, anterior–posterior rotational acceleration of a head generated intracranial pressure changes, recorded by fibre optic pressure sensors, inserted ipsilaterally in the parieto‐temporal and the occipital lobes. Two levels of rotational acceleration were used in the experiments; one higher, corresponding to the threshold limit for moderate diffuse brain injury, and one lower, close to being noninjurious. Several pressure recordings were performed in each rabbit at the two acceleration levels. The pressure recordings invariably revealed the same general characteristics of rapid, positive and negative pressures within the brain, with variations in amplitude and duration, lasting for up to 10 ms. A major finding was the generation of powerful negative pressures, as low as 0.3 bars in absolute pressure. The most prominent difference in amplitudes of the negative peak pressures between the two applied acceleration levels was demonstrated at the parieto‐temporal location. The presented pressure recordings are the first to disclose the generation of transient, powerful intracerebral pressures at rotational acceleration of the head, which must be considered in studies of brain injury generation and distribution as well as prevention.
Functional properties and synaptic integration of genetically labelled dopaminergic neurons in intrastriatal grafts
Authors: Sørensen Andreas Toft , Thompson Lachlan , Kirik Deniz , Björklund Anders , Lindvall Olle , Kokaia Merab
Published: May 2005

Intrastriatal grafts of fetal ventral mesencephalic tissue, rich in dopaminergic neurons, can reverse symptoms in Parkinson's disease. For development of effective cell replacement therapy, other sources of dopaminergic neurons, e.g. derived from stem cells, are needed. However, the electrophysiological properties grafted cells need to have in order to induce substantial functional recovery are poorly defined. It has not been possible to prospectively identify and record from dopaminergic neurons in fetal transplants. Here we used transgenic mice expressing green fluorescent protein under control of the rat tyrosine hydroxylase promoter for whole‐cell patch‐clamp recordings of endogenous and grafted dopaminergic neurons. We transplanted ventral mesencephalic tissue from E12.5 transgenic mice into striatum of neonatal rats with or without lesions of the nigrostriatal dopamine system. The transplanted cells exhibited intrinsic electrophysiological properties typical of substantia nigra dopaminergic neurons, i.e. broad action potentials, inward rectifying currents with characteristic ‘sag’, and spontaneous action potentials. The grafted dopaminergic neurons also received functional excitatory and inhibitory synaptic inputs from the host brain, as shown by the presence of both spontaneous and stimulation‐evoked excitatory and inhibitory postsynaptic currents. Occurrence of spontaneous excitatory and inhibitory currents was lower, and of spontaneous action potentials was higher, in neurons placed in the dopamine‐depleted striatum than of those in the intact striatum. Our findings define specific electrophysiological characteristics of transplanted fetal dopaminergic neurons, and we provide the first direct evidence of functional synaptic integration of these neurons into host neural circuitries.
Neurotrophin‐4/5 is required for the early growth of regenerating axons in peripheral nerves
Authors: English Arthur W. , Meador William , Carrasco Dario I.
Published: May 2005

The requirement of the trkB ligand, neurotrophin‐4/5 (NT‐4/5), for the growth of regenerating axons in the peripheral nervous system (PNS) is not well established. We studied regenerating axon growth in transected peripheral nerves of thy‐1‐YFP‐H mice that had been repaired using allografts obtained from brain‐derived neurotrophic factor (BDNF) or NT‐4/5 knockout mice. Lengths of profiles of YFP+ axons measured in these grafts were compared with those measured in grafts obtained from wild‐type donors. When compared with axon profiles measured in grafts from wild‐type donors, axon profile lengths measured in grafts from homozygous (NT‐4/5−/−) or heterozygous (NT‐4/5+/−) mice were significantly shorter. In contrast, the lengths of axon profiles measured in grafts from BDNF+/− mice were not significantly different from those measured in grafts from wild‐type mice. A reduced amount of BDNF, but not NT‐4/5, is sufficient to promote the elongation of regenerating axons in the PNS. When grafts from wild‐type or NT‐4/5−/− mice were treated acutely at the time of surgical repair either with exogenous BDNF or NT‐4/5, the lengths of axon profiles measured in the grafts were significantly longer than those measured in grafts from untreated wild‐type mice. These findings are consistent with a requirement for NT‐4/5 from within the pathway used by regenerating axons for the successful growth of those axons in peripheral nerves.
NF‐κB transcription factor is required for inhibitory avoidance long‐term memory in mice
Authors: Freudenthal Ramiro , Boccia Mariano M. , Acosta Gabriela B. , Blake Mariano G. , Merlo Emiliano , Baratti Carlos M. , Romano Arturo
Published: May 2005

Although it is generally accepted that memory consolidation requires regulation of gene expression, only a few transcription factors (TFs) have been clearly demonstrated to be specifically involved in this process. Increasing research data point to the participation of the Rel/nuclear factor‐κB (NF‐κB) family of TFs in memory and neural plasticity. Here we found that two independent inhibitors of NF‐κB induced memory impairment in the one‐trial step‐through inhibitory avoidance paradigm in mice: post‐training administration of the drug sulfasalazine and 2 h pretraining administration of a double‐stranded DNA oligonucleotide containing the NF‐κB consensus sequence (κB decoy). Conversely, one base mutation of the κB decoy (mut‐κB decoy) injection did not affect long‐term memory. Accordingly, the κB decoy inhibited NF‐κB in hippocampus 2 h after injection but no inhibition was found with mut‐κB decoy administration. A temporal course of hippocampal NF‐κB activity after training was determined. Unexpectedly, an inhibition of NF‐κB was found 15 min after training in shocked and unshocked groups when compared with the naïve group. Hippocampal NF‐κB was activated 45 min after training in both shocked and unshocked groups, decreasing 1 h after training and returning to basal levels 2 and 4 h after training. On the basis of the latter results, we propose that activation of NF‐κB in hippocampus is part of the molecular mechanism involved in the storage of contextual features that constitute the conditioned stimulus representation. The results presented here provide the first evidence to support NF‐κB activity being regulated in hippocampus during consolidation, stressing the role of this TF as a conserved molecular mechanism for memory storage.
Heritability, correlations and in silico mapping of locomotor behavior and neurochemistry in inbred strains of mice
Authors: Mhyre T. R. , Chesler E. J. , Thiruchelvam M. , Lungu C. , Cory‐Slechta D. A. , Fry J. D. , Richfield E. K.
Published: May 2005

The midbrain dopamine system mediates normal and pathologic behaviors related to motor activity, attention, motivation/reward and cognition. These are complex, quantitative traits whose variation among individuals is modulated by genetic, epigenetic and environmental factors. Conventional genetic methods have identified several genes important to this system, but the majority of factors contributing to the variation remain unknown. To understand these genetic and environmental factors, we initiated a study measuring 21 behavioral and neurochemical traits in 15 common inbred mouse strains. We report trait data, heritabilities and genetic and non‐genetic correlations between pheno‐types. In general, the behavioral traits were more heritable than neurochemical traits, and both genetic and non‐genetic correlations within these trait sets were high. Surprisingly, there were few significant correlations between the behavioral and the individual neurochemical traits. However, striatal serotonin and one measure of dopamine turnover (DOPAC/DA) were highly correlated with most behavioral measures. The variable accounting for the most variation in behavior was mouse strain and not a specific neurochemical measure, suggesting that additional genetic factors remain to be determined to account for these behavioral differences. We also report the prospective use of the in silico method of quantitative trait loci (QTL) analysis and demonstrate difficulties in the use of this method, which failed to detect significant QTLs for the majority of these traits. These data serve as a framework for further studies of correlations between different midbrain dopamine traits and as a guide for experimental cross designs to identify QTLs and genes that contribute to these traits.
Long‐term individual housing in C57BL/6J and DBA/2 mice: assessment of behavioral consequences
Authors: Võikar V. , Polus A. , Vasar E. , Rauvala H.
Published: May 2005

The aim of the present study was to investigate the effects of individual housing on mouse behavior. The male mice of the C57BL/6J and DBA/2 strains were separated at the age of 4 weeks and kept in individual housing for 7 weeks until behavioral testing began. Their behavior was compared to the group‐housed mice in a battery of tests during the following 7 weeks. The single‐housed mice were hyperactive and displayed reduced habituation in the tests assessing activity and exploration. Reduced anxiety was established in the elevated plus‐maze, but an opposite effect was observed in the dark–light (DL) and hyponeophagia tests. Immobility in the forced swimming test was reduced by social isolation. The DBA mice displayed higher anxiety‐like behavior than the B6 mice in the plus‐maze and DL exploration test, but hyponeophagia was reduced in the DBA mice. Moreover, all effects of individual housing on the exploratory and emotional behavior were more evident in the DBA than in the B6 mice. Novel object recognition and fear conditioning (FC) were significantly impaired in the single‐housed mice, whereas water‐maze (WM) learning was not affected. Marked strain differences were established in all three learning tests. The B6 mice performed better in the object recognition and FC tasks. Initial spatial learning in the WM was faster and memory retention slightly enhanced in the B6 mice. The DBA mice displayed lower preference to the new and enhanced preference to the old platform location than the B6 mice after reversal learning in the WM. We conclude that individual housing has strong strain‐ and test‐specific effects on emotional behavior and impairs memory in certain tasks.
Female oxytocin gene‐knockout mice, in a semi‐natural environment, display exaggerated aggressive behavior
Authors: Ragnauth A. K. , Devidze N. , Moy V. , Finley K. , Goodwillie A. , Kow L.‐M. , Muglia L. J. , Pfaff D. W.
Published: May 2005

Compared to results from a generation of neuropharmacological work, the phenotype of mice lacking the oxytocin (OT) peptide gene was remarkably normal. An important component of the current experiments was to assay OT‐knockout (OTKO) and wild‐type (WT) littermate control mice living under controlled stressful conditions designed to mimic more closely the environment for which the mouse genome evolved. Furthermore, our experimental group was comprised of an all‐female population, in contrast to previous studies which have focused on all‐male populations. Our data indicated that aggressive behaviors initiated by OTKO during a food deprivation feeding challenge were considerably more intense and diverse than aggressive behaviors initiated by WT. From the measures of continuous social interaction in the intruder paradigm, it emerged that OTKO mice were more offensively aggressive (attacking rumps and tails) than WT. In a test of parental behaviors, OTKO mice were 100% infanticidal while WT were 16% infanticidal and 50% maternal. Finally, ‘alpha females’ (always OTKO) were identified in each experiment. They were the most aggressive, the first to feed and the most dominant at nesting behaviors. Semi‐natural environments are excellent testing environments for elucidating behavioral differences between transgenic mice and their WT littermates which may not be ordinarily discernible. Future studies of mouse group behavior should include examining female groupings in addition to the more usual all‐male groups.
Comparison of SPME headspace analysis to U.S. EPA method 5030/8260B for MTBE monitoring
Authors: Stringfellow William T. , Oh Keun‐Chan
Published: May 2005

Methyl tert‐butyl ether (MTBE) is one of the most common ground water contaminants in the United States. Ground water contaminated with MTBE is also likely to be contaminated with tert‐butyl alcohol (TBA) because TBA is a component of commercial‐grade MTBE, can also be used as a fuel oxygenate, and is a biodegradation product of MTBE. In California, MTBE is subject to reporting at concentrations >3 μg/L, and TBA has a drinking water action level of 12 μg/L. We describe a simple, automated solid‐phase microextraction (SPME) method for the analysis of MTBE and TBA in water. The headspace (HS) of a water sample is extracted with a carboxen/polydimethylsiloxane SPME fiber and the MTBE and TBA are desorbed into a gas chromatograph (GC) and detected using a mass spectrometer (MS). The method is optimized for the routine analysis of MTBE and TBA, with a level of quantitation of 0.3 and 4 μg/L, respectively, in water. The lower level of detection for MTBE is 0.03 μg/L using this method. This HS extraction SPME is applicable to the measurement of both MTBE and TBA at concentrations below regulatory action levels. This method was compared with the certified U.S. EPA Method 5030/8260B (purge and trap/GC/MS) using split samples. Results from the SPME‐HS/GC/MS method were directly comparable to those from the U.S. EPA Method 5030/8260B. This method provides a simple, inexpensive, accurate, and sensitive alternative to the U.S. EPA Method 5030/8260B for the analysis of MTBE and TBA in water samples.
Simultaneous estimation of diffusive Volatile Organic Compound (VOC) fluxes and Non‐Aqueous Phase Liquid (NAPL) saturation in the vadose zone
Authors: Werner David , Broholm Mette , Höhener Patrick
Published: May 2005

Soil‐gas monitoring is a widely used tool to observe the migration of volatile organic compounds (VOCs) at contaminated sites. By combining this technique with natural gradient tracer methods, diffusive contaminant fluxes can be measured in situ, and non–aqueous phase liquid (NAPL) can be detected and roughly quantified. This work describes the new approach and its application at a field site in Denmark with an emplaced NAPL contamination. Soil‐gas probes with a low dead volume were installed at 1‐m depths in the sandy vadose zone, and a small volume of gas containing conservative and partitioning tracers was injected. Soil‐gas samples were withdrawn subsequently during 1 to 4 h and analyzed simultaneously for VOCs and tracers. Tracers detected the NAPL reliably, and the combined data allowed for a close delineation of the source zone. The calculated NAPL saturation deviated by up to a factor of 3 from the analyses of soil cores. Better agreement was found by taking the NAPL composition into consideration, which is, however, generally unknown at the actual field sites. In addition, the tracers were also used to estimate effective diffusion coefficients in situ, which varied by a factor of 2 between various locations. From these data, diffusive contaminant vapor fluxes were quantified without additional laboratory experiments or the use of empirical relationships. The new approach yields a better site investigation with a few additional measurements.
Evaluation of a small mechanical and pneumatic bladder pump for water quality sampling
Authors: McCall Wesley
Published: May 2005

Two small‐diameter (≤0.5‐inch/13‐mm O.D.) bladder pumps were evaluated under the U.S. EPA Environmental Technology Verification Program to assess their ability to provide representative water quality samples for several volatile organic compounds (VOCs) and major element cations. Both a pneumatic bladder pump (PnBP) and a newly designed mechanical bladder pump (MBP) were evaluated. Since the MBP does not require compressed air to operate, the field logistics are simplified and cost of conducting low‐flow sampling can be reduced. Replicate samples were collected from an above‐ground standpipe spiked with selected VOCs and cations. Low‐flow sampling protocol was followed during collection of replicate samples from six direct push (DP)–installed monitoring wells at Tyndall Air Force Base, Florida. Simple statistical methods are used to evaluate the sample quality provided by the pumps as compared to reference samples. F‐tests are used to evaluate pump sample precision, and t‐tests are applied to evaluate comparability of the pump sample results to the colocated reference or port sample results. Statistical analysis reveals that the samples collected with the pumps provide precision comparable to that observed in the reference samples. Significantly greater variability was observed between the pump and reference samples collected from the DP wells than was observed during the standpipe trials. The results and statistics from the trials at the standpipe indicate that both the PnBP and MBP provide water quality samples that are comparable to the reference samples, for the analytes investigated.
Paired‐pulse transcranial magnetic stimulation protocol applied to visual cortex of anaesthetized cat: effects on visually evoked single‐unit activity
Authors: Moliadze Vera , Giannikopoulos Dimitrios , Eysel Ulf T. , Funke Klaus
Published: May 2005

In this study, we tested the paired‐pulse transcranial magnetic stimulation (ppTMS) protocol – a conditioning stimulus (CS) given at variable intervals prior to a test stimulus (TS) – for visually evoked single‐unit activity in cat primary visual cortex. We defined the TS as being supra‐threshold when it caused a significant increase or decrease in the visually evoked activity. By systematically varying the interstimulus interval (ISI) between 2 and 30 ms and the strength of CS within the range 15–130% of TS, we found a clear dependence of the ppTMS effect on CS strength but little relation to ISI. The CS effect was strongest with an ISI of 3 ms and steadily declined for longer ISIs. A switch from enhancement of intracortical inhibition at short ISIs (2–5 ms, SICI) to intracortical facilitation (ICF) at longer ISIs (7–30 ms), as demonstrated for human motor cortex, was not evident. Whether the CS caused facilitation or suppression of the TS effect mainly depended on the strength of CS and the polarity of the TS effect: within a range of 60–130% a positive correlation between ppTMS and TS effect was evident, resulting in a stronger facilitation if the TS caused facilitation of visual activity, and more suppression if the TS was suppressive by itself. The correlation inverted when CS was reduced to 15–30%. The ppTMS effect was not simply the sum of the CS and TS effect, it was much smaller at weak CS strength (15–50%) but stronger than the sum of CS and TS effects at CS strength 60–100%. Differences in the physiological state between sensory and motor cortices and the interactions of paired synaptic inputs are discussed as possible reasons for the partly different effects of ppTMS in cat visual cortex and human motor cortex.
Relationship between intracellular pH and proton mobility in rat and guinea‐pig ventricular myocytes
Authors: Swietach Pawel , Vaughan‐Jones Richard D.
Published: May 2005

Intracellular H+ ion mobility in eukaryotic cells is low because of intracellular buffering. We have investigated whether Hi+ mobility varies with pHi. A dual microperfusion apparatus was used to expose guinea‐pig or rat myocytes to small localized doses (3–5 mm) of ammonium chloride (applied in Hepes‐buffered solution). Intracellular pH (pHi) was monitored confocally using the fluorescent dye, carboxy‐SNARF‐1. Local ammonium exposure produced a stable, longitudinal pHi gradient. Its size was fed into a look‐up table (LUT) to give an estimate of the apparent intracellular proton diffusion coefficient (DappH). LUTs were generated using a diffusion–reaction model of Hi+ mobility based on intracellular buffer diffusion. To examine the pHi sensitivity of DappH, whole‐cell pHi was initially displaced using a whole‐cell ammonium or acetate prepulse, before locally applying the low dose of ammonium. In both rat and guinea‐pig, DappH decreased with pHi over the range 7.5–6.5. In separate pipette‐loading experiments, the intracellular diffusion coefficient for carboxy‐SNARF‐1 (a mobile‐buffer analogue) exhibited no significant pHi dependence. The pHi sensitivity of DappH is thus likely to be governed by the mobile fraction of intrinsic buffering capacity. These results reinforce the buffer hypothesis of Hi+ mobility. The pHi dependence of DappH was used to characterize the mobile and fixed buffer components, and to estimate Dmob (the average diffusion coefficient for intracellular mobile buffer). One consequence of a decline in Hi+ mobility at low pHi is that it will predispose the myocardium to pHi nonuniformity. The physiological relevance of this is discussed.
NO signalling decodes frequency of neuronal activity and generates synapse‐specific plasticity in mouse cerebellum
Authors: Namiki Shigeyuki , Kakizawa Sho , Hirose Kenzo , Iino Masamitsu
Published: May 2005

Nitric oxide (NO) is an intercellular messenger regulating neuronal functions. To visualize NO signalling in the brain, we generated a novel fluorescent NO indicator, which consists of the heme‐binding region (HBR) of soluble guanylyl cyclase and the green fluorescent protein. The indicator (HBR–GFP) was expressed in the Purkinje cells of the mouse cerebellum and we imaged NO signals in acute cerebellar slices upon parallel fibre (PF) activation with a train of burst stimulations (BS, each BS consisting of five pulses at 50 Hz). Our results showed that the intensity of synaptic NO signal decays steeply with the distance from the synaptic input near PF–Purkinje cell synapses and generates synapse‐specific long‐term potentiation (LTP). Furthermore, the NO release level has a bell‐shaped dependence on the frequency of PF activity. At an optimal frequency (1 Hz), but not at a low frequency (0.25 Hz) of a train of 60 BS, NO release as well as LTP was induced. However, both NO release and LTP were significantly reduced at higher frequencies (2–4 Hz) of BS train due to cannabinoid receptor‐mediated retrograde inhibition of NO generation at the PF terminals. These results suggest that synaptic NO signalling decodes the frequency of neuronal activity to mediate synaptic plasticity at the PF–Purkinje cell synapse.
Manipulation of peripheral neural feedback loops alters human corticomuscular coherence
Authors: Riddle C. Nicholas , Baker Stuart N.
Published: May 2005

Sensorimotor EEG shows ∼20 Hz coherence with contralateral EMG. This could involve efferent and/or afferent components of the sensorimotor loop. We investigated the pathways responsible for coherence genesis by manipulating nervous conduction delays using cooling. Coherence between left sensorimotor EEG and right EMG from three hand and two forearm muscles was assessed in healthy subjects during the hold phase of a precision grip task. The right arm was then cooled to 10°C for ∼90 min, increasing peripheral motor conduction time (PMCT) by ∼35% (assessed by F‐wave latency). EEG and EMG recordings were repeated, and coherence recalculated. Control recordings revealed a heterogeneous subject population. In 6/15 subjects (Group A), the corticomuscular coherence phase increased linearly with frequency, as expected if oscillations were propagated along efferent pathways from cortex to muscle. The mean corticomuscular conduction delay for intrinsic hand muscles calculated from the phase–frequency regression slope was 10.4 ms; this is smaller than the delay expected for conduction over fast corticospinal pathways. In 8/15 subjects (Group B), the phase showed no dependence with frequency. One subject showed both Group A and Group B patterns over different frequency ranges. Following cooling, averaged corticomuscular coherence was decreased in Group A subjects, but unchanged for Group B, even though both groups showed comparable slowing of nervous conduction. The delay calculated from the slope of the phase–frequency regression was increased following cooling. However, the size of this increase was around twice the rise in PMCT measured using the F‐wave (regression slope 2.33, 95% confidence limits 1.30–3.36). Both afferent and efferent peripheral nerves will be slowed by similar amounts following cooling. The change in delay calculated from the coherence phase therefore better matches the rise in total sensorimotor feedback loop time caused by cooling, rather than just the change in the efferent limb. A model of corticomuscular coherence which assumes that only efferent pathways contribute cannot be reconciled to these results. The data rather suggest that afferent feedback pathways may also play a role in the genesis of corticomuscular coherence.
Protection from Experimental Asthma by an Endogenous Bronchodilator
Authors: Que Loretta G. , Liu Limin , Yan Yun , Whitehead Gregory S. , Gavett Stephen H. , Schwartz David A. , Stamler Jonathan S.
Published: May 2005

Mechanisms that protect against asthma remain poorly understood.
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-nitrosoglutathione (GSNO), an endogenous bronchodilator, is depleted from asthmatic airways, suggesting a protective role. We report that, following allergen challenge, wild-type mice exhibiting airway hyperresponsivity have increased airway levels of the enzyme GSNO reductase (GSNOR) and are depleted of lung
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-nitrosothiols (SNOs). In contrast, mice with genetic deletion of GSNOR exhibit increases in lung SNOs and are protected from airway hyperresponsivity. Our results indicate that endogenous SNOs, governed by GSNOR, are critical regulators of airway responsivity and may provide new therapeutic approaches to asthma.
MicroRNA Expression in Zebrafish Embryonic Development
Authors: Wienholds Erno , Kloosterman Wigard P. , Miska Eric , Alvarez-Saavedra Ezequiel , Berezikov Eugene , de Bruijn Ewart , Horvitz H. Robert , Kauppinen Sakari , Plasterk Ronald H. A.
Published: May 2005

MicroRNAs (miRNAs) are small noncoding RNAs, about 21 nucleotides in length, that can regulate gene expression by base-pairing to partially complementary mRNAs. Regulation by miRNAs can play essential roles in embryonic development. We determined the temporal and spatial expression patterns of 115 conserved vertebrate miRNAs in zebrafish embryos by microarrays and by in situ hybridizations, using locked-nucleic acid–modified oligonucleotide probes. Most miRNAs were expressed in a highly tissue-specific manner during segmentation and later stages, but not early in development, which suggests that their role is not in tissue fate establishment but in differentiation or maintenance of tissue identity.
Creating and sacrificing embryos for stem cells
Authors: Devolder K
Published: May 2005

The compromise position that accepts the use and derivation of stem cells from spare in vitro fertilisation embryos but opposes the creation of embryos for these purposes is a very weak ethical position. This paper argues that whatever the basis is on which defenders of this viewpoint accord intrinsic value to the embryo, once they accept the creation and sacrifice of embryos to benefit infertile people with a child-wish, they do not have a sound moral argument to condemn the creation and sacrifice of embryos to benefit ill and injured people.
Ethical concerns regarding guidelines for the conduct of clinical research on children
Authors: Edwards S D , McNamee M J
Published: May 2005

In this article we examine ethical aspects of the involvement of children in clinical research, specifically those who are incapable of giving informed consent to participate. The topic is, of course, not a new one in medical ethics but there are some tensions in current guidelines that, in our view, need to be made explicit and which need to be responded to by the relevant official bodies. In particular, we focus on tensions between the World Medical Association Declaration of Helsinki, and the guidance offered by the British Medical Association, the Royal College of Paediatrics and Child Health (formerly the British Paediatric Association), and the Council for International Organizations of Medical Sciences. We conclude with a call for these organisations to make their guidance explicit in relation to the World Medical Association Declaration.
The unwitting sacrifice problem
Authors: Gillett G
Published: May 2005

The diagnosis of bipolar disorder has been linked to giftedness of various sorts and this raises a special problem in that it is likely that the condition has a genetic basis. Therefore it seems possible that in the near future we will be able to detect and eliminate the gene predisposing to the disorder. This may mean, however, that, as a society, we lose the associated gifts. We might then face a difficult decision either way in that it is unclear that we are preventing an unalloyed bad when we diagnose and eliminate bipolar disorder through prenatal genetic testing and yet if we allow the individual to be born we are condemning that person to being an unwitting sacrifice in that they might well suffer considerable net distress as a result of our need to keep our gene pool enriched in the relevant way.
Reducing health disparity in Taiwan: quantifying the role of smoking
Authors: Cheng T Y , Wen C P , Tsai S P , Chung W S I , Hsu C C
Published: May 2005

Objective:To assess the impact of smoking disparities on health disparities, in terms of gap in life expectancy, in Taiwan cities and counties.

Methods:Using the decomposition method of life expectancy, the contribution of each disease category to the life expectancy gap was quantitatively expressed as the number of years of life. The smoking attributable fraction (SAF) was calculated for each city and county based on their respective smoking prevalence and relative risk for each smoking related disease. The smoking attributable gap (SAG) in life expectancy between two sites is the sum of the difference in SAF between two sites for each smoking related disease multiplied by the number of years this disease contributed to the life expectancy gap.

Results:Significant health and smoking disparities were present among the 23 cities and counties in Taiwan. These health disparities and smoking disparities were highly correlated (R2 =  0.3676). Generally, the health gap increased with increasing smoking disparity. The disparity in smoking prevalence and intensity among cities and counties in Taiwan was responsible for up to 19% of the health disparity. The health disparity is also highly correlated (R2 =  0.3745) with SAG in life expectancy.

Conclusions:Reducing smoking is important to health, and reducing the smoking disparity is also important for reducing the health disparity observed in Taiwan. The larger the health disparity is, the more important the smoking attributable disparity could be. The reduction of smoking disparities could be a realistic and cost effective way toward reducing health disparities.
Workplace smoking related absenteeism and productivity costs in Taiwan
Authors: Tsai S P , Wen C P , Hu S C , Cheng T Y , Huang S J
Published: May 2005

Objective:To estimate productivity losses and financial costs to employers caused by cigarette smoking in the Taiwan workplace.

Methods:The human capital approach was used to calculate lost productivity. Assuming the value of lost productivity was equal to the wage/salary rate and basing the calculations on smoking rate in the workforce, average days of absenteeism, average wage/salary rate, and increased risk and absenteeism among smokers obtained from earlier research, costs due to smoker absenteeism were estimated. Financial losses caused by passive smoking, smoking breaks, and occupational injuries were calculated.

Results:Using a conservative estimate of excess absenteeism from work, male smokers took off an average of 4.36 sick days and male non-smokers took off an average of 3.30 sick days. Female smokers took off an average of 4.96 sick days and non-smoking females took off an average of 3.75 sick days. Excess absenteeism caused by employee smoking was estimated to cost US$178 million per annum for males and US$6 million for females at a total cost of US$184 million per annum. The time men and women spent taking smoking breaks amounted to nine days per year and six days per year, respectively, resulting in reduced output productivity losses of US$733 million. Increased sick leave costs due to passive smoking were approximately US$81 million. Potential costs incurred from occupational injuries among smoking employees were estimated to be US$34 million.

Conclusions:Financial costs caused by increased absenteeism and reduced productivity from employees who smoke are significant in Taiwan. Based on conservative estimates, total costs attributed to smoking in the workforce were approximately US$1032 million.