bluuebunny/crossref_metadata_2025 huggingface dataset:
Differentiation of an auditory neuronal cell line suitable for cell transplantation
Authors: Nicholl A. J. , Kneebone A. , Davies D. , Cacciabue‐Rivolta D. I. , Rivolta M. N. , Coffey P. , Holley M. C.
Published: July 2005

The auditory neuroblast cell line US/VOT‐N33 (N33), which is conditionally immortal, was studied as an in vitro model for the differentiation of spiral ganglion neurons (SGNs) and as a candidate for cell transplantation in rodents. It expresses numerous molecular markers characteristic of auditory neuroblasts, including the transcription factors GATA3, NeuroD, Brn3a and Islet1, as well as the neuronal cytoskeletal protein β3‐tubulin. It displays active migratory behaviour in vitro and in vivo. In the presence of the fibroblast growth factors FGF1 or FGF2 it differentiates bipolar morphologies similar to those of native SGNs. In coculture with neonatal cochlear tissue it is repelled from epithelial surfaces but not from native SGNs, alongside which it extends parallel neuronal processes. When injected into the retina in vivo, EGFP‐labelled N33 cells were traced for 1–2 weeks and migrated rapidly within the subretinal space. Cells that found their way into the retinal ganglion cell layer extended multiple processes but did not express β3‐tubulin. The ability of N33 to migrate, to differentiate, to localize with native SGNs in vitro and to survive in vivo suggests that they provide an effective model for SGN differentiation and for cell transplantation into the ear.
The role of the dorsomedial striatum in instrumental conditioning
Authors: Yin Henry H. , Ostlund Sean B. , Knowlton Barbara J. , Balleine Bernard W.
Published: July 2005

Considerable evidence suggests that, in instrumental conditioning, rats learn the relationship between actions and their specific consequences or outcomes. The present study examined the role of the dorsomedial striatum (DMS) in this type of learning after excitotoxic lesions and reversible, muscimol‐induced inactivation. In three experiments, rats were first trained to press two levers for distinct outcomes, and then tested after training using a variety of behavioural assays that have been established to detect action‐outcome learning. In Experiment 1, pre‐training lesions of the posterior DMS abolished the sensitivity of rats' instrumental performance to both outcome devaluation and contingency degradation when tested in extinction, whereas lesions of the anterior DMS had no effect. In Experiment 2, both pre‐training and post‐training lesions of the posterior DMS were equally effective in reducing the sensitivity of performance both to devaluation and degradation treatments. In Experiment 3, the infusion of muscimol into the posterior DMS selectively abolished sensitivity of performance to devaluation and contingency degradation without impairing the ability of rats to discriminate either the instrumental actions performed or the identity of the earned outcomes. Taken together, these results suggest that the posterior region of the DMS is a crucial neural substrate for the acquisition and expression of action–outcome associations in instrumental conditioning.
Frequency‐dependent impairment of hippocampal LTP from NMDA receptors with reduced calcium permeability
Authors: Pawlak Verena , Jensen Vidar , Schupp Bettina J. , Kvello Ane , Hvalby Øivind , Seeburg Peter H. , Köhr Georg
Published: July 2005

Changes in postsynaptic Ca2+ levels are essential for alterations in synaptic strength. At hippocampal CA3‐to‐CA1 synapses, the Ca2+ elevations required for LTP induction are typically mediated by NMDA receptor (NMDAR) channels but a contribution of NMDAR‐independent Ca2+ sources has been implicated. Here, we tested the sensitivity of different protocols modifying synaptic strength to reduced NMDAR‐mediated Ca2+ influx by employing mice genetically programmed to express in forebrain principal neurons an NR1 form that curtails Ca2+ permeability. Reduced NMDAR‐mediated Ca2+ influx did not facilitate synaptic depression in CA1 neurons of these genetically modified mice. However, we observed that LTP could not be induced by pairing low frequency synaptic stimulation (LFS pairing) with postsynaptic depolarization, a protocol that induced robust LTP in wild‐type mice. By contrast to LFS pairing, similar LTP levels were generated in both genotypes when postsynaptic depolarization was paired with high frequency synaptic stimulation (HFS). This indicates that the postsynaptic Ca2+ elevation also reached threshold during HFS in the mutant, probably due to summation of NMDAR‐mediated Ca2+ influx. However, only in wild‐type mice did repeated HFS further enhance LTP. All tested forms of LTP were blocked by the NMDAR antagonist D‐AP5. Collectively, our results indicate that only NMDAR‐dependent Ca2+ sources (NMDARs and Ca2+‐dependent Ca2+ release from intracellular stores) mediate LFS pairing‐evoked LTP. Moreover, LTP induced by the first HFS stimulus train required lower Ca2+ levels than the additional LTP obtained by repeated trains.
S‐cones do not contribute to the OFF‐midget pathway in the retina of the marmoset, Callithrix jacchus
Authors: Lee Sammy C. S. , Telkes Ildiko , Grünert Ulrike
Published: July 2005

It is well established that in primate retina both medium‐ and long‐wavelength‐sensitive cone types provide input to the midget‐parvocellular pathway. The question, however, whether short‐wavelength‐sensitive (S or ‘blue’) cones provide input to the OFF‐division of the midget‐parvocellular pathway is still controversial. In the present study, we investigated the connections of nearly 400 S‐cones with OFF‐midget bipolar cells in central and peripheral retina of a New World monkey, the marmoset. Horizontal sections or pieces of whole retinae were double‐labelled with an antiserum to S‐cone opsin to identify S‐cones and antibodies to the cell adhesion molecule CD15 to identify OFF‐midget bipolar cells. Peanut agglutinin coupled to a fluorescent tag was used to label the cone pedicles of all cone types. Peanut agglutinin was also used to distinguish S‐cones from the other cone types. The sections were analysed with deconvolution microscopy. We found that nearly all pedicles of medium‐ and long‐wavelength‐sensitive cones are located opposite distinct dendritic clusters formed by OFF‐midget bipolar cells. By contrast, the S‐cone pedicles are not located opposite dendritic clusters. Instead, S‐cones make sparse contacts with CD15‐labelled processes. Some of these processes protruded from OFF‐midget bipolar clusters, whereas others could be traced to a diffuse bipolar cell type. Thus, in the marmoset retina the midget‐parvocellular system does not carry a blue‐OFF signal.
How does transcranial DC stimulation of the primary motor cortex alter regional neuronal activity in the human brain?
Authors: Lang Nicolas , Siebner Hartwig R. , Ward Nick S. , Lee Lucy , Nitsche Michael A. , Paulus Walter , Rothwell John C. , Lemon Roger N. , Frackowiak Richard S.
Published: July 2005

Transcranial direct current stimulation (tDCS) of the primary motor hand area (M1) can produce lasting polarity‐specific effects on corticospinal excitability and motor learning in humans. In 16 healthy volunteers, O positron emission tomography (PET) of regional cerebral blood flow (rCBF) at rest and during finger movements was used to map lasting changes in regional synaptic activity following 10 min of tDCS (± 1 mA). Bipolar tDCS was given through electrodes placed over the left M1 and right frontopolar cortex. Eight subjects received anodal or cathodal tDCS of the left M1, respectively. When compared to sham tDCS, anodal and cathodal tDCS induced widespread increases and decreases in rCBF in cortical and subcortical areas. These changes in rCBF were of the same magnitude as task‐related rCBF changes during finger movements and remained stable throughout the 50‐min period of PET scanning. Relative increases in rCBF after real tDCS compared to sham tDCS were found in the left M1, right frontal pole, right primary sensorimotor cortex and posterior brain regions irrespective of polarity. With the exception of some posterior and ventral areas, anodal tDCS increased rCBF in many cortical and subcortical regions compared to cathodal tDCS. Only the left dorsal premotor cortex demonstrated an increase in movement related activity after cathodal tDCS, however, modest compared with the relatively strong movement‐independent effects of tDCS. Otherwise, movement related activity was unaffected by tDCS. Our results indicate that tDCS is an effective means of provoking sustained and widespread changes in regional neuronal activity. The extensive spatial and temporal effects of tDCS need to be taken into account when tDCS is used to modify brain function.
Nociceptive spinal withdrawal reflexes but not spinal dorsal horn wide‐dynamic range neuron activities are specifically inhibited by halothane anaesthesia in spinalized rats
Authors: You Hao‐Jun , Colpaert Francis C. , Arendt‐Nielsen Lars
Published: July 2005

The aim of the present study was to investigate the spinal cord effects and sites of action of different inhaled concentrations (0.5–2%) of the anaesthetic, halothane. Simultaneous recordings were made of 3 Hz, suprathreshold (1.5 × T) electrically evoked spinal dorsal horn (DH) wide‐dynamic range (WDR) neuron responses and of single motor unit (SMU) electromyographic (EMG) responses underlying the spinal withdrawal reflex in spinalized Wistar rats. Compared with the baseline responses obtained with 0.5% halothane, the electrically evoked early responses of the DH WDR neurons as well as the SMUs were only depressed by the highest, 2% concentration of halothane. In contrast, 1.5% halothane markedly inhibited the late responses of the DH WDR neurons, whereas 1% halothane started to significantly depress the late responses of the SMUs. Likewise, wind‐up of the WDR neuron late responses was inhibited by 1.5–2% halothane, whereas 1–2% halothane significantly depressed wind‐up of the SMU EMG late responses. The inhibitory effects of 2% halothane on the early and the late responses of the DH WDR neurons, but not of the SMUs, were completely reversed by opioid µ‐receptor antagonist naloxone (0.04 mg/kg). However, no significant effects of naloxone were found on different responses of the DH WDR neurons as well as the SMUs at 0.5–1% halothane, suggesting that different concentrations of halothane may modulate different spinal receptors. We conclude that halothane at high concentrations (1.5–2%) seems to play a predominant inhibitory role via spinal multireceptors on ventral horn (VH) motor neurons, and less on DH sensory WDR neurons, of the spinal cord.
Roles of NMDA receptor NR2A and NR2B subtypes for long‐term depression in the anterior cingulate cortex
Authors: Toyoda Hiroki , Zhao Ming‐Gao , Zhuo Min
Published: July 2005

The anterior cingulate cortex (ACC) is thought to be important for the establishment, consolidation and retrieval of permanent memory. In many brain regions, including the hippocampus, it is suggested that long‐term potentiation (LTP) and long‐term depression (LTD), the cellular mechanisms for learning and memory, require the activation of glutamate N‐methyl‐d‐aspartate receptors (NMDARs). In the hippocampus, the NR2A subunit is believed to be involved in the induction of LTP, whereas the NR2B subunit contributes to the formation of LTD. However, LTD has been less well studied in the ACC as compared with the hippocampus and little is known about the role of NMDA subtype receptors in cingulate LTD. Here we show that LTD can be induced by the combination of presynaptic stimulation with postsynaptic depolarization (‘pairing training’) in adult mouse ACC neurons. This form of LTD is an NMDAR‐ and voltage‐dependent mechanism and a postsynaptic Ca2+ increase is required for the induction of LTD. Furthermore, our studies provide direct physiological evidence that both NR2A and NR2B subunits are involved in the induction of LTD in the ACC.
The Cost Effectiveness of the UK's Sovereign Debt Portfolio*
Authors: Coe Patrick J. , Hashem Pesaran M. , Vahey Shaun P.
Published: July 2005

This paper provides a recursive empirical analysis of the scope for cost minimization in public debt management when the debt manager faces a given short‐term interest rate dictated by monetary policy as well as risk and market impact constraints. It simulates the ‘real‐time’ interest costs of alternative portfolios for UK government debt between April 1985 and March 2000. These portfolios are constructed using forecasts of return spreads based on a recursive modelling procedure. While we find statistically significant evidence of predictability, the interest cost savings are quite small when portfolio shares are constrained to lie within historical bounds.
Monetary Frameworks and Institutional Constraints: UK Monetary Policy Reaction Functions, 1985–2003
Authors: Adam Christopher , Cobham David , Girardin Eric
Published: July 2005

Monetary policy reaction functions are estimated for the UK over three periods – 1985–90, 1992–97 and 1997–2003 – in order to disentangle two effects: the switch from an emphasis on exchange rate stabilization to inflation targeting, and the introduction of instrument‐independence in 1997. The external factors considered include US as well as German interest rates, and this leads to the identification of ‘domestic’ and ‘international’ models of the reaction function. The results suggest that it is the changes in the institutional arrangements rather than those in the targeting regime which have been decisive in the development of policy in this period.
Prewhitening Bias in HAC Estimation*
Authors: Sul Donggyu , Phillips Peter C. B. , Choi Chi‐Young
Published: July 2005

Heteroskedasticity and autocorrelation consistent (HAC) estimation commonly involves the use of prewhitening filters based on simple autoregressive models. In such applications, small sample bias in the estimation of autoregressive coefficients is transmitted to the recolouring filter, leading to HAC variance estimates that can be badly biased. The present paper provides an analysis of these issues using asymptotic expansions and simulations. The approach we recommend involves the use of recursive demeaning procedures that mitigate the effects of small‐sample autoregressive bias. Moreover, a commonly used restriction rule on the prewhitening estimates (that first‐order autoregressive coefficient estimates, or largest eigenvalues, >0.97 be replaced by 0.97) adversely interferes with the power of unit‐root and [Kwiatkowski, Phillips, Schmidt and Shin (1992)Journal of Econometrics, Vol. 54, pp. 159–178] (KPSS) tests. We provide a new boundary condition rule that improves the size and power properties of these tests. Some illustrations of the effects of these adjustments on the size and power of KPSS testing are given. Using prewhitened HAC estimates and the new boundary condition rule, the KPSS test is consistent, in contrast to KPSS testing that uses conventional prewhitened HAC estimates [Lee, J. S. (1996)Economics Letters, Vol. 51, pp. 131–137].
Programme Evaluation with Unobserved Heterogeneity and Selective Implementation: The Mexican PROGRESA Impact on Child Nutrition
Authors: Behrman Jere R. , Hoddinott John
Published: July 2005

This paper considers the impact of Programa de Educación, Salud y Alimentación (PROGRESA), a large Mexican rural anti‐poverty programme that had an evaluation sample in which overall treatment was randomly assigned to some communities but not others, on child nutrition. When we examine the impact of PROGRESA based on the presumption of randomized allocations, we find that PROGRESA had no or even a negative impact on child nutrition. However, not all children designated to receive nutritional supplements actually did so. Our preferred estimates – child fixed‐effects estimates that control for unobserved heterogeneity that is correlated with access to the supplement – indicate a significantly positive and fairly substantial programme effect of the nutritional supplements on children 12–36 months. They imply an increase of about a sixth in mean growth per year for these children and a lower probability of stunting. Effects are somewhat larger for children from poorer communities but whose mothers are functionally literate. The long‐term consequences of these improvements are non‐trivial; its impact working through adult height alone could result in a 2.9% increase in lifetime earnings.
Epidemiology and Impact of Childhood Molluscum Contagiosum: A Case Series and Critical Review of the Literature
Authors: Braue Anna , Ross Gayle , Varigos George , Kelly Heath
Published: July 2005

Abstract:  Parents of 30 children with clinically diagnosed molluscum contagiosum were surveyed to assess their perception of the condition, its treatment, its impact on their everyday lives, and on the children themselves. Among parents, 82% reported that molluscum contagiosum concerned them moderately or greatly. Concerns focused on physical issues associated with the infection, such as scarring, itching, chance of spread to peers, pain, and the effects of treatments. Quality of life was not affected. Molluscum contagiosum was most common among school‐age children. Eighteen of 29 respondents swam in public pools, a common activity in children of this age. All epidemiologic studies of molluscum contagiosum in otherwise healthy individuals, published since 1966, have been critically reviewed herein. The review confirms an association between swimming pool use and molluscum contagiosum. Age, living in close proximity, skin‐to‐skin contact, sharing of fomites, and residence in tropical climates were also associated with higher rates of infection while sex, seasonality, and hygiene showed no such association.
Oral Lichen Planus in Childhood
Authors: Laeijendecker Ronald , Van Joost Theodoor , Tank Bhupendra , Oranje Arnold P. , Neumann H. A. Martino
Published: July 2005

Abstract:  Oral lichen planus is rare in childhood, and only a few reports on this subject have appeared in the literature. Our objective was to report individual cases of oral lichen planus in childhood from our practice and to review the literature on this subject. We recruited patients younger than 18 years with oral lichen planus and documented several clinical aspects, the histopathology, patch tests, and blood examination findings. Three patients from about 10,000 dermatology patients younger than 18 years seen from 1994 to 2003 were included. Of these three, an Asian girl aged 11 years had an asymptomatic, hyperkeratotic variant of oral lichen planus, which disappeared without any treatment after 1 year. An Asian boy aged 16 years had an erosive oral lichen planus with severe pain, which healed after intensive local and systemic treatment in 2 years. A Caucasian girl aged 14 years had a hyperkeratotic variant with a little soreness, which disappeared with local treatment after 3 months. Our findings indicated that oral lichen planus in childhood is rare and therefore at present it is not possible to draw firm conclusions considering its nature and etiology. Oral lichen planus in childhood seems to occur preferentially in those of Asian race. The clinical features resemble those of oral lichen planus in adults. However, generally the prognosis of oral lichen planus in childhood seems to be more favorable than in adults.
High Incidence of Balanitis Xerotica Obliterans in Boys with Phimosis: Prospective 10‐Year Study
Authors: Kiss András , Király László , Kutasy Balázs , Merksz Miklós
Published: July 2005

Abstract:  This prospective study was designed to address the incidence and clinical and histologic characteristics of balanitis xerotica obliterans in a large random pediatric population with phimosis. We investigated 1178 boys who presented consecutively with phimosis between 1991 and 2001. All patients who underwent complete circumcision and surgical specimens were typed histologically as early, intermediate, or late forms of this disorder or as nonspecific chronic inflammation. Patients with balanitis xerotica obliterans were controlled at 1, 6, and 12 months postoperatively, then yearly. Balanitis xerotica obliterans was found in 471 of the 1178 patients (40%), with the highest incidence in boys aged 9 to 11 years (76%). Secondary phimosis occurred in 93% of boys with balanitis xerotica obliterans and in 32% of those without the disorder. In six instances of balanitis xerotica obliterans, meatotomy and in one meatoplasty was performed, as well as circumcision. On histologic evaluation, we found 19% had early, 60% intermediate, and 21% late form of balanitis xerotica obliterans. Glanular lesions disappeared completely within 6 months in 229 out of 231 patients. Our data strongly suggest that the true incidence of childhood balanitis xerotica obliterans is higher than previously assumed. Its incidence peaks in the 9 to 11 years age group, in whom secondary phimosis was almost exclusively caused by balanitis xerotica obliterans.
Peeling Skin Syndrome with Aminoaciduria
Authors: Inamadar Arun C. , Palit Aparna
Published: July 2005

Abstract:  A 12‐year‐old child presented with asymptomatic, noninflammatory, generalized peeling of the skin since early childhood. He was diagnosed as having type A continual peeling skin syndrome. Associated increased excretion of cystine and histidine in the urine has hitherto not been reported.
Atypical IgA/IgG Pemphigus Involving the Skin, Oral Mucosa, and Colon in a Child: A Novel Variant of IgA Pemphigus?
Authors: Bruckner Anna L. , Fitzpatrick James E. , Hashimoto Takashi , Weston William L. , Morelli Joseph G.
Published: July 2005

Abstract:  Immune‐mediated blistering diseases are rare in childhood, with the subset of IgA pemphigus being extremely uncommon. A child with a bullous disorder of the oral mucosa, skin, and colon is reported because of the unusual nature of the clinical and laboratory findings. Immunofluorescence studies demonstrated both intercellular epidermal and basement membrane zone deposition of IgA and IgG antibodies, as well as intercellular colonic deposition of IgA antibodies. IgA and IgG ELISA tests were positive for desmoglein 3 as the intercellular epidermal antigen. The generation of multiple antibodies against several potential antigenic targets suggests epitope spreading may play a role in this disease. We believe this represents a novel variant of IgA pemphigus.
Influence of ionic strength on the time course of force development and phosphate release by dogfish muscle fibres
Authors: West Timothy G. , Ferenczi Michael A. , Woledge Roger C. , Curtin N. A.
Published: July 2005

We measured the effects of ionic strength (IS), 200 (standard) and 400 mmol l−1(high), on force and ATP hydrolysis during isometric contractions of permeabilized white fibres from dogfish myotomal muscle at their physiological temperature, 12°C. One goal was to test the validity of our kinetic scheme that accounts for energy release, work production and ATP hydrolysis. Fibres were activated by flash photolysis of theP3‐1‐(2 nitrophenyl) ethyl ester of ATP (NPE‐caged ATP), and time‐resolved phosphate (Pi) release was detected with the fluorescent protein MDCC‐PBP,N‐(2[1‐maleimidyl]ethyl)‐7‐diethylamino‐coumarin‐3‐carboxamide phosphate binding protein. High IS slowed the transition from rest to contraction, but as the fibres approached the isometric force plateau they showed little IS sensitivity. By 0.5 s of contraction, the force and the rate of Pirelease at standard and high IS values were not significantly different. A five‐step reaction mechanism was used to account for the observed time courses of force and Pirelease in all conditions explored here. Only the rate constants for reactions of ATP, ADP and Piwith the contractile proteins varied with IS, thus suggesting that the actin–myosin interactions are largely non‐ionic. Our reaction scheme also fits previous results for intact fibres.
Electrophysiological characterization of native Na+–HCO3– cotransporter current in bovine parotid acinar cells
Authors: Yamaguchi Souichirou , Ishikawa Toru
Published: July 2005

Using patch‐clamp and molecular biological techniques, we identified and characterized membrane currents most likely generated by an electrogenic Na+–HCO3− cotransporter (NBCe) in acutely dissociated bovine parotid acinar (BPA) cells. When BPA cells were dialysed with a N‐methyl‐d‐glucamine (NMDG)‐glutamate‐rich pipette solution, switching a Na‐glutamate‐rich, nominally HCO3−‐free bath solution to the one containing 25 mm HCO3−, but not Cl−, elicited a whole‐cell current with a linear current–voltage relation. The HCO3− evoked current was abolished by total replacement of extracellular Na+ (Na+o) with NMDG or by 0.5 mm 4,4′‐diisothiocyanato‐stilbene‐2,2′‐disulfonic acid (DIDS), and was only partially supported by Li+o, but not by K+o, Cs+o, and cholineo. The reversal potential shift of DIDS (0.5 mm)‐sensitive current induced by a change of [Na+]o corresponded to an apparent coupling ratio of HCO3− to Na+ of 2. RT‐PCR analysis showed the presence of transcripts of NBCe1‐B, but not NBCe1‐A in BPA cells. Electrophysiological and pharmacological properties of whole‐cell currents recorded from HEK293 cells transfected with the NBCe1‐B, which was cloned from BPA cells resembled those of the native currents. Non‐invasive measurements of membrane potential changes in the cell‐attached patch configuration indicated that an NBCe activity is present in intact unstimulated BPA cells bathed in a 25 mm HCO3−‐containing solution. Collectively, these results not only suggest that an NBCe is present, functional and may be mediated, at least in part, by NBCe1‐B in BPA cells, but also provide the first electrophysiological characterization of transport properties of NBCe expressed in native exocrine glands.
Light responses and light adaptation in rat retinal rods at different temperatures
Authors: Nymark S. , Heikkinen H. , Haldin C. , Donner K. , Koskelainen A.
Published: July 2005

Rod responses to brief pulses of light were recorded as electroretinogram (ERG) mass potentials across isolated, aspartate‐superfused rat retinas at different temperatures and intensities of steady background light. The objective was to clarify to what extent differences in sensitivity, response kinetics and light adaptation between mammalian and amphibian rods can be explained by temperature and outer‐segment size without assuming functional differences in the phototransduction molecules. Corresponding information for amphibian rods from the literature was supplemented by new recordings from toad retina. All light intensities were expressed as photoisomerizations per rod (Rh*). In the rat retina, an estimated 34% of incident photons at the wavelength of peak sensitivity caused isomerizations in rods, as the (hexagonally packed) outer segments measured 1.7 μm × 22 μm and had specific absorbance of 0.016 μm−1 on average. Fractional sensitivity (S) in darkness increased with cooling in a similar manner in rat and toad rods, but the rat function as a whole was displaced to a ca 0.7 log unit higher sensitivity level. This difference can be fully explained by the smaller dimensions of rat rod outer segments, since the same rate of phosphodiesterase (PDE) activation by activated rhodopsin will produce a faster drop in cGMP concentration, hence a larger response in rat than in toad. In the range 15–25°C, the waveform and absolute time scale of dark‐adapted dim‐flash photoresponses at any given temperature were similar in rat and toad, although the overall temperature dependence of the time to peak (tp) was somewhat steeper in rat (Q10≈ 4 versus 2–3). Light adaptation was similar in rat and amphibian rods when measured at the same temperature. The mean background intensity that depressed S by 1 log unit at 12°C was in the range 20–50 Rh* s−1 in both, compared with ca 4500 Rh* s−1 in rat rods at 36°C. We conclude that it is not necessary to assume major differences in the functional properties of the phototransduction molecules to account for the differences in response properties of mammalian and amphibian rods.
Connexin‐specific cell‐to‐cell transfer of short interfering RNA by gap junctions
Authors: Valiunas V. , Polosina Y. Y. , Miller H. , Potapova I. A. , Valiuniene L. , Doronin S. , Mathias R. T. , Robinson R. B. , Rosen M. R. , Cohen I. S. , Brink P. R.
Published: July 2005

The purpose of this study was to determine whether oligonucleotides the size of siRNA are permeable to gap junctions and whether a specific siRNA for DNA polymerase β (pol β) can move from one cell to another via gap junctions, thus allowing one cell to inhibit gene expression in another cell directly. To test this hypothesis, fluorescently labelled oligonucleotides (morpholinos) 12, 16 and 24 nucleotides in length were synthesized and introduced into one cell of a pair using a patch pipette. These probes moved from cell to cell through gap junctions composed of connexin 43 (Cx43). Moreover, the rate of transfer declined with increasing length of the oligonucleotide. To test whether siRNA for pol β was permeable to gap junctions we used three cell lines: (1) NRK cells that endogenously express Cx43; (2) Mβ16tsA cells, which express Cx32 and Cx26 but not Cx43; and (3) connexin‐deficient N2A cells. NRK and Mβ16tsA cells were each divided into two groups, one of which was stably transfected to express a small hairpin RNA (shRNA), which gives rise to siRNA that targets pol β. These two pol β knockdown cell lines (NRK‐kcdc and Mβ16tsA‐kcdc) were co‐cultured with labelled wild type, NRK‐wt or Mβ16tsA‐wt cells or N2A cells. The levels of pol β mRNA and protein were determined by semiquantitative RT‐PCR and immunoblotting. Co‐culture of Mβ16tsA‐kcdc cells with Mβ16tsA‐wt, N2A or NRK‐wt cells had no effect on pol β levels in these cells. Similarly, co‐culture of NRK‐kcdc with N2A cells had no effect on pol β levels in the N2A cells. In contrast, co‐culture of NRK‐kcdc with NRK‐wt cells resulted in a significant reduction in pol β in the wt cells. The inability of Mβ16tsA‐kcdc cells to transfer siRNA is consistent with the fact that oligonucleotides of the 12 nucleotide length were not permeable to Cx32/Cx26 channels. This suggested that Cx43 but not Cx32/Cx26 channels allowed the cell‐to‐cell movement of the siRNA. These results support the novel hypothesis that non‐hybridized and possible hybridized forms of siRNA can move between mammalian cells through connexin‐specific gap junctions.
Of Whale Knuckles and Placental Trees
Authors: de Muizon Christian
Published: July 2005

The Rise of Placental Mammals
. Origins and Relationships of the Major Extant Clades.
Kenneth D. Rose and J. David Archibald, Eds.
. Johns Hopkins University Press, Baltimore, MD, 2005. 271 pp. $95, £63.50. ISBN 0-8018-8022-X.

Focusing on anatomical evidence but not ignoring findings from molecular studies, the contributors discuss our current understanding of the initial radiation and ordinal relationships of placental mammals.
Creating, Varying, and Growing Single-Site Molecular Contacts
Authors: Siaj Mohamed , McBreen Peter H.
Published: July 2005

The known range of chemisorption bonds forms the toolbox for the design of electrical contacts in molecular electronics devices. Double-bond contacts to technologically relevant materials would be attractive for a number of reasons. They are truly single-site, bonding to a single surface atom. They obviate the need for a thiol linkage, and they may be amenable to further modification through olefin-metathesis methodologies. We report olefin-metathesis methods for establishing, varying, and growing thermally stable double-bond contacts to molybdenum carbide, a conducting material.
Global Mammal Conservation: What Must We Manage?
Authors: Ceballos Gerardo , Ehrlich Paul R. , Soberón Jorge , Salazar Irma , Fay John P.
Published: July 2005

We present a global conservation analysis for an entire “flagship” taxon, land mammals. A combination of rarity, anthropogenic impacts, and political endemism has put about a quarter of terrestrial mammal species, and a larger fraction of their populations, at risk of extinction. A new global database and complementarity analysis for selecting priority areas for conservation shows that ∼11% of Earth's land surface should be managed for conservation to preserve at least 10% of terrestrial mammal geographic ranges. Different approaches, from protection (or establishment) of reserves to countryside biogeographic enhancement of human-dominated landscapes, will be required to approach this minimal goal.
Effects of Telomerase and Telomere Length on Epidermal Stem Cell Behavior
Authors: Flores Ignacio , Cayuela María L. , Blasco María A.
Published: July 2005

A key process in organ homeostasis is the mobilization of stem cells out of their niches. We show through analysis of mouse models that telomere length, as well as the catalytic component of telomerase, Tert, are critical determinants in the mobilization of epidermal stem cells. Telomere shortening inhibited mobilization of stem cells out of their niche, impaired hair growth, and resulted in suppression of stem cell proliferative capacity in vitro. In contrast, Tert overexpression in the absence of changes in telomere length promoted stem cell mobilization, hair growth, and stem cell proliferation in vitro. The effects of telomeres and telomerase on stem cell biology anticipate their role in cancer and aging.
Seeing Similarities
Authors: Sarkar Sahotra
Published: July 2005

The Evolution-Creation Struggle
.
By Michael Ruse
. Harvard University Press, Cambridge, MA, 2005. 310 pp. $25.95, £16.95, €24. ISBN 0-674-01687-4.

Exploring the philosophical foundations of creationism and evolutionary biology, the author views the opposing positions as closely related responses to a loss of religious faith in the Western world.
Multiple Causes of High Extinction Risk in Large Mammal Species
Authors: Cardillo Marcel , Mace Georgina M. , Jones Kate E. , Bielby Jon , Bininda-Emonds Olaf R. P. , Sechrest Wes , Orme C. David L. , Purvis Andy
Published: July 2005

Many large animal species have a high risk of extinction. This is usually thought to result simply from the way that species traits associated with vulnerability, such as low reproductive rates, scale with body size. In a broad-scale analysis of extinction risk in mammals, we find two additional patterns in the size selectivity of extinction risk. First, impacts of both intrinsic and environmental factors increase sharply above a threshold body mass around 3 kilograms. Second, whereas extinction risk in smaller species is driven by environmental factors, in larger species it is driven by a combination of environmental factors and intrinsic traits. Thus, the disadvantages of large size are greater than generally recognized, and future loss of large mammal biodiversity could be far more rapid than expected.
Ecophysiology of seed dormancy and germination in the mesic woodland herbaceous perennial Corydalis ambigua (Fumariaceae) in Japan
Authors: Kondo Tetsuya , Okubo Nori , Miura Taku , Baskin Carol C , Baskin Jerry M
Published: July 2005

In Japan, the herbaceous perennial Corydalis ambigua Cham. et Schlecht. occurs in Tohoku and Hokkaido, where it grows in deciduous woodlands. Seeds have an underdeveloped embryo that is physiologically dormant at the time of dispersal in late May. In laboratory experiments, embryos did not grow when kept continuously at 5 °C or at alternating diurnal temperatures of 25/15 °C. However, following warm stratification at 25/15 °C, they grew at 15/5 °C and continued to do so at 0 °C. Radicles emerged after a relatively long period at 0 or 5 °C, following warm stratification at 25/15 °C and then incubation at 15/5 °C. Embryos began to develop in autumn in seeds under near-natural conditions in a metal frame-house, and they had grown to an average of about 90% of their full length by December. Beginning in December, the seed coat split, exposing the endosperm, and in March both the radicle and the cotyledon emerged under the snow or immediately after snow melt. Dormancy in seeds of C. ambigua is the same as that in seeds of Hydrastis canadensis L., which has been described as a special type of deep simple epicotyl morphophysiological dormancy.Key words: Corydalis ambigua, embryo growth, morphophysiological dormancy, seed germination phenology, underdeveloped embryo.
The effects of fire and stand age on seedling establishment ofPulsatilla patensin a pine-dominated boreal forest
Authors: Kalamees Rein , Püssa Kersti , Vanha-Majamaa Ilkka , Zobel Kristjan
Published: July 2005

Successful management of disturbance-related endangered plant species requires thorough knowledge concerning their recruitment ecology. Pulsatilla patens (L.) Mill. is found in northern European forests that in the past have been subjected to a periodic wildfire regime and, thus, is supposedly adapted to corresponding changes in forest light conditions and thickness of the moss and litter layers. We tested whether this is true in a field experiment where seeds of P. patens were sown in experimentally burned and control boreal Scots pine forest sites of different successional age (clear-cut, 30 years old, 45 years old). The germination and early establishment of P. patens was enhanced in the experimentally burned conditions and was more successful in younger successional stages. On the other hand, in sites with a tree layer, the germination of P. patens was better in relatively darker areas, suggesting that the negative effect of successional age is probably not a result of changing light conditions, but rather a result of thicker moss and litter layers in the later successional stages.Key words: boreal forest, germination, forest fire, litter layer, Pulsatilla patens, seed sowing.
Pilot-scale struvite recovery from anaerobic digester supernatant at an enhanced biological phosphorus removal wastewater treatment plant
Authors: Britton A , Koch F A , Mavinic D S , Adnan A , Oldham W K , Udala B
Published: July 2005

Pilot testing of a fluidized bed reactor used to recover phosphate, in the form of struvite, from anaerobic digester supernatant was conducted at the Advanced Wastewater Treatment Plant, City of Penticton, British Columbia. The main objective of this study was to demonstrate the ability of the reactor to remove at least 70% of the phosphate in the supernatant from a digester fed with a combination of primary and secondary sludge. It was found that the operation of the reactor could be controlled to achieve any desired level of phosphorus removal up to 90%. Analysis of the recovered struvite crystals showed essentially pure struvite (>99% by weight) with small amounts of calcium (<0.5% by weight) and traces of potassium and iron. The recovered crystals had mean diameters increasing from 0.5 to 1.8 mm over the course of the study. The increasing diameters are believed to be the result of changes in the crystal structures that caused them to become stronger over the course of the study.Key words: crystallization, nutrient removal, phosphorus recovery, struvite, sludge treatment, wastewater.
Kinetic removal of lead from water by decaying Tamrix leaves
Authors: Zaggout F R
Published: July 2005

Removal of lead ions from aqueous solutions by Tamrix gallica leaves was studied. The factors that affected this removal were investigated. These factors are metal ion concentration, tamrix leave concentration, pH, presence of competing ions, agitation, crushing, drying, presence of complexing agent, and leaf extract. Application of the Freundlich adsorption isotherm on the present results has been examined and the parameters of this isotherm have been calculated. The order of reaction between lead ions and Tamrix gallica leaves has been determined and a mechanism for this interaction has been suggested. Key words: lead removal, Tamrix leaves, adsorption, pH.
Nitrifying bacteria addition into reactors operating near washout conditions for nitrification
Authors: Head Melanie A , Oleszkiewicz Jan A
Published: July 2005

Sequencing batch reactors, at 10 °C, operating near the minimum solids retention time (washout conditions) for nitrification, were seeded daily with nitrifying biomass acclimated to 10 and 20 °C. Effluent NH3-N levels were decreased to less than 5 mg/L within 23 d for both seeding regimes. Once seeding was terminated, the reactor seeded with nitrifying bacteria acclimated to 10 °C continued to achieve full nitrification, whereas the reactor seeded with nitrifiers acclimated to 20 °C saw a rapid increase in effluent NH3-N concentrations. Nitrification was not completely lost in the latter reactor after seeding was stopped for 30 d. Key words: nitrification, bioaugmentation, temperature, solids retention time (SRT), dewatering liquor, wastewater.
Caractérisation et traitement des résidus de contrôle de la pollution de l'air (RCPA) d'incinérateurs de déchets municipaux par un procédé de lixiviation en milieu basique
Authors: Hammy Fatima , Mercier Guy , Blais Jean-François
Published: July 2005

A detailed characterization of the different types of air pollution control residues (APCR) produced in municipal waste incinerators has been performed. The analysis of the Pb distribution in boiler and electrofilter ashes has shown that the separation of these ashes in two fractions (<125 µm and >125 µm) allows to get a coarse fraction slightly contaminated and a finer fraction more heavily contaminated, which can be treated by chemical means. Scanning electron microscope  energy-dispersive spectrometry (SEM-EDS) techniques have been used to identify the most dominant forms of the lead particles. Lead present in used lime is principally associated with oxides in a carrying phase of calcium chloride or phosphate. Lead present in boiler and electrofilter ashes is principally associated with silicates and phosphates. Finally, only one leaching step in alkaline aqueous solution is required to remove a large proportion of the leachable lead in APCR and to reach the allowed level by the toxicity characteristic leaching procedure test (TCLP) and neutral water test. Key words: lead, leaching, incinerator, air pollution control residues (APCR), ash, removal, heavy metal, toxicity characteristic leaching procedure test (TCLP).
Solution charts for the consolidation of double soil layers
Authors: Zhu Guofu , Yin Jian-Hua
Published: July 2005

This technical note presents solution charts for determining the average degree of consolidation of double soil layers for both one-way and two-way drainage. The influence of two newly introduced independent parameters on the average degree of consolidation is examined. The solution procedure is described clearly. When the compressibility, permeability, and thickness of the material making up each layer are given, the charts can be used to obtain the average degree of consolidation of the double soil layers for consolidation settlement calculations.Key words: consolidation, double soil layers, solution charts, drainage, settlement, soil.
Foundation design for the Emirates Twin Towers, Dubai
Authors: Poulos Harry George , Davids Andrew J
Published: July 2005

This paper describes the foundation design process adopted for two high-rise buildings in Dubai, the Emirates Twin Towers. The foundation system for each of the towers was a piled raft, founded on deep deposits of calcareous soils and rocks. The paper outlines the geotechnical investigations undertaken, the field and laboratory testing programs, and the design process and describes how potential issues of low skin friction and cyclic degradation of skin friction due to wind loading were addressed. An advanced numerical computer analysis was used for the design process, which was carried out using a limit state approach. This necessitated analysis of a large number of load cases, and the paper describes how the information was processed to produce design information. A comprehensive program of pile load testing was undertaken, and class A predictions of both axial and lateral loaddeflection behaviour were in fair agreement with the load test results. Despite this agreement, the overall settlements of the towers observed during construction were significantly less than predicted. The possible reasons for the discrepancy are discussed.Key words: case history, footings and foundations, full-scale tests, piles, rafts, settlement.
A critical-state constitutive model for liquefiable sand
Authors: Imam SM Reza , Morgenstern Norbert R , Robertson Peter K , Chan David H
Published: July 2005

This paper presents a critical-state constitutive model for sands over a wide range of void ratios and consolidation pressures in a triaxial plane. A single set of parameters, including a unique critical-state line reached at large strain, is also used in the model, and differences in behavior in triaxial compression and extension are modeled by accounting for anisotropy at small and medium ranges of strain. The model uses a capped yield surface (YS), which is characterized by its size and shape. Following evidence in past literature, the stress ratio at the peak point of the capped YS of loose sands is approximated by the stress ratio measured at the peak point of their undrained effective stress path. Yielding parameters obtained using this stress ratio are also applied in modeling dense sand behavior and drained loading. These parameters account for the effects of inherent anisotropy, void ratio, and confining pressure on yielding stresses and are readily determined from laboratory tests, but further research is required on their determination from field data. The model accounts for stress-induced and inherent anisotropies, using different parameters, which develop and evolve independently. Emphasis is placed on proper modeling of aspects of loose sand behavior that affect their susceptibility to flow liquefaction.Key words: constitutive modeling, liquefaction, loose sand, critical state, dilatancy, hardening.
Undrained shear behaviour of sands subjected to large shear displacement and estimation of excess pore-pressure generation from drained ring shear tests
Authors: Okada Yasuhiko , Sassa Kyoji , Fukuoka Hiroshi
Published: July 2005

Undrained shear behaviour of fine silica and weathered granitic sand subjected to large shear displacement is examined. Parallel experiments using ring shear and the triaxial compression tests on soil specimens through a wide range of initial void ratios were conducted to investigate undrained shear strength as the key factor in the flow-like motion of landslides. The steady-state undrained shear strengths achieved in ring shear tests were, in general, smaller than those in the triaxial compression tests, probably because of the excess pore-pressure generation by grain crushing within the shear zone that occurred in ring shear. Very low steady-state shear strengths were achieved, however, in triaxial compression tests on the dense silica sand in which well-defined shear surfaces developed in the cylindrical specimens. In these triaxial compression tests, shear deformation must have been concentrated on these surfaces to generate excess pore pressure similar to that found in ring shear tests. An attempt was made to estimate excess pore pressure generated in undrained ring shear tests using the results of drained ring shear tests. The equivalent normal stress calculated as the ratio of volumetric strain in the drained test to the coefficient of volume change was introduced as a parameter for the estimation of excess pore-pressure generation for the large shear displacement that is usually found in landslides. Equivalent normal stress from drained tests was almost the same as the generated excess pore pressure in undrained tests with up to 1 m of shear displacement, at which the steady state was reached.Key words: undrained shear strength, excess pore pressure, equivalent normal stress, ring shear test, triaxial compression test, liquefaction.