bluuebunny/crossref_metadata_2025_split huggingface dataset:
A kinematic and electromyographic analysis of the development of sitting posture in infants
Authors: Harbourne Regina T. , Giuliani Carol , Neela Jane Mac 
Published: January 2005

AbstractThis study was designed to describe the development of posture control in sitting in response to a natural perturbation. Seven normal infants 2 to 5 months of age were tested at two stages of independent sitting development. Trunk support was removed from infants while sitting erect and the postural responses were videotaped and EMG recorded from the upper trunk extensors, lumbar paraspinals, gluteus maximus, rectus femoris, hamstrings, and abdominals. Kinematic variables (trunk displacement, trunk velocity, trunk curvature) and an EMG variable (pattern of muscle activation) were analyzed with computer programs. Between Stages 1 and 2 of sitting development, anterior trunk displacement and velocity decreased significantly, although the trunk extension curve did not change significantly. Infants had variable muscle responses during Stage 1; however, during Stage 2 EMG analysis revealed less variability and the emergence of postural synergies. Overall, lumbar paraspinals, hamstrings, and quadriceps were the muscles most frequently active during the postural response. Each subject had a preferred synergy, with the most common synergies being a lumbar paraspinalhamstring synergy and a lumbar paraspinal‐quadriceps synergy. These data provide evidence that trunk displacement and trunk velocity decrease in infants develop independent sitting posture, and these variables may be used to measure improvement in sitting control. We suggest that the control of sitting posture is related to the emergence and preferred use of the paraspinal‐hamstring and paraspinal‐quadriceps synergies. © 1993 Johan Wiley & Sons, Inc.
Maternal regulation of adrenocortical activity in the infant rat: Effects of feeding
Authors: Rosenfeld Patricia , Ekstrand Jeffrey , Olson Emily , Suchecki Deborah , Levine Seymour 
Published: January 2005

AbstractBasal and stress‐induced corticosterone release in the infant rat has been shown to be inhibited by some aspect of maternal care. The following studies examined specific maternal cues that might be responsible for this regulation. In Experiments 1 and 2, 12‐day‐old pups remained with their dam but were either prevented or not from feeding; at the end of 24 hr, basal and stress‐induced corticosterone levels were measured. Only those animals that were able to feed showed the hyporesponsiveness characteristic of nondeprived animals, suggesting that feeding rather than some other aspect of maternal care was the critical variable. In Experiment 3, all animals were maternally deprived, and some of them were fed via an intracheek cannula. Once again, feeding led to a pronounced diminution in both basal and stress‐induced levels of corticosterone. Our results point to feeding as one of the critical features responsible for the inhibitory effect of the dam on the infant's adrenocortical activity. © 1993 Wiley & sons. Inc.
Specific antibody levels in free‐ranging rhesus monkeys: Relationships to plasma hormones, cardiac parameters, and early behavior
Authors: Laudenslager Mark L. , Rasmussen Kathlyn L. R. , Berman Carol M. , Suomi Stephen J. , Berger Christy B. 
Published: January 2005

AbstractLevels of tetanus‐specific antibodies were assessed in free‐ranging, yearling rhesus monkeys following prophylactic immunization with tetanus toxoid. Each subject's behavior had been observed between 11 and 25 weeks of age and approximately 2 months later during its mother's first concentrated mating period as a part of another study. Prior to immunization, at approximately 1 year of age, cardiovascular parameters, and several plasma parameters [cortisol, adrenocorticotrophic hormone (ACTH), growth hormone (GH), interleukin‐2 (IL‐2), and total plasma immunoglobulin G (IgG)] were measured during a brief period of captivity. Antibody titers noted approximately 2 weeks after immunization were related to cardiovascular parameters. Thus, yearlings with high heart rates and low heart rate variability during captivity had the highest tetanus‐specific serum IgG. Levels of plasma cortisol, ACTH, total IgG, and IL‐2 noted at the time of capture were unrelated to subsequent antibody levels. Antibody titers were, however, positively correlated with GH noted immediately following capture on the day prior to immunization. Antibody titers were also related to the infants' behavior observed during their mother's first concentrated mating period, Infants who were most distressed (high levels of distress vocalization) when their mother resumed mating (a time particularly stressful for free‐ranging rhesus infants) showed lower antibody titers to tetanus immunization as a yearling. The present observations add support to the existence of a relationship between behavior during exposure to an early stressor and later immune regulation and that certain cardiovascular parameters may be related to certain indicators of immunoregulation. © 1993 John Wiley & Sons, Inc.
Influence of early life events on immune reactivity in adult mice
Authors: Neveu Pierre J. , Deleplanque Brigitte , Puglisi‐Allegra Stefano , D'amato Francesca R. , Cabib Simona 
Published: January 2005

AbstractThe effects of postnatal manipulations on different immune parameters were investigated in adult female mice. Postnatal stress consisted of a 15‐min daily exposure to clean bedding (temperature Mayntained at 35°C) for the first 2 weeks of life in the absence of the mother but in the presence of littermates. Controls were unhandled until weaning. At 60 days of age, female mice stressed during postnatal development showed enhanced immune reactivity as assessed by NK‐cell activity and T‐cell mitogenesis in comparison with unhandled mice. By contrast, B‐lymphocyte proliferation induced by lipopolysaccharide (LPS) was not affected by alterations of postnatal environment. Furthermore, the association between immune reactivity and behavioral lateralization observed in adult mice was not altered by postnatal stress.© 1994 John Wiley & Sons, Inc.
But is it rigorous? Trustworthiness and authenticity in naturalistic evaluation
Authors: Lincoln Yvonna S. , Guba Egon G. 
Published: January 2005

AbstractThe emergence of a new paradigm of inquiry (naturalistic) has, unsurprisingly enough, led to a demand for rigorous criteria that meet traditional standards of inquiry. Two sets are suggested, one of which, the “trustworthiness” criteria, parallels conventional criteria, while the second, “authenticity” criteria, is implied directly by new paradigm assumptions.
Quasi‐experimentation in a critical multiplist mode
Authors: Shadish, William R. , Cook Thomas D. , Houts Arthur C. 
Published: January 2005

AbstractSince it is usually the case that no defensible option for performing a task within quasi‐experimentation is unbiased, it is desirable to select several options that reflect biases in different directions. This aim is to avoid constant biases and to overlook only those biases that can be considered least plausible.
Conducting social experiments
Authors: Boruch Robert F. 
Published: January 2005

AbstractRandomized field experiments have been regarded as a gold standard in producing good evidence about the effects of social programs. But they have not been easy to conduct. In the past decade, the use of alternative randomization plans and incentives has contributed to their operational feasibility; legal, ethical, and professional arguments for experimentation have matured; and expectations have become better aligned with practical constraints that are likely to be encountered.
Direct cash low‐income housing assistance
Authors: Kennedy Stephen D. 
Published: January 2005

AbstractEvidence from evaluation of low‐income housing assistance programs in this country indicates that: those which use existing housing are less expensive than those which require new housing construction, but existing housing programs do not reach people in the worst housing. Program effects are relatively small, except for people who are induced to change their housing, and the effect for others is primarily to reduce their rent burden.
Mental health program evaluation and needs assessment
Authors: Ciarlo James A. , Windle Charles 
Published: January 2005

AbstractThe course of evaluation in mental health has been altered by the sociopolitical context of the 1970s and 1980s. Among the lessons learned are (1) the limitations of some evaluation technologies, (2) improvements that have occurred in others, and (3) the need for “echelon‐specific” evaluations. Insufficient recognition has been given to the need for both internal and external evaluation and replication.
Theory‐based evaluation of AIDS‐related knowledge, attitudes, and behavior changes
Authors: Conner Ross F. , Mishra Shiraz I. , Lewis Megan A. , Bryer Samantha , Marks Jeff , Lai Mini , Clark Lisa 
Published: January 2005

AbstractThree theoretical approaches to disease prevention and health promotion are discussed and an example of an AIDS prevention curriculum that used theories to formulate the intervention and to guide the evaluation research is presented.
Public and private management of wastewater treatment: A comparative study
Authors: O'Toole, Jr. Laurence J. 
Published: January 2005

AbstractContracts with private firms offer one mode of alternative provision for public services. Evidence on this approach to the operation of municipal wastewater treatment facilities indicates that performance advantages may be possible for certain types of communities. Savings are possible in larger facilities and when the local government assumes a relatively active and energetic oversight role.
Electrical coupling between astrocytes and between oligodendrocytes studied in mammalian cell cultures
Authors: Kettenmann Helmut , Ranson Bruce R. 
Published: January 2005

AbstractThe characteristics of electrical coupling between astrocytes and between oligodendrocytes were analyzed in cell cultures derived from rodent central nervous system. Experiments were carried out by impaling one member of a glial pair with separate voltage recording and current passing electrodes (cell 1) and the other cell, a measured distance from the first, with a voltage‐recording electrode (cell 2). Astrocyte pairs within 300 μm of one another were always coupled. The coupling ratio was determined for 23 astrocytic pairs various distances apart, and decreased with distance in a roughly exponential manner. The average coupling ratio of astrocytes within 100 μm of each other was 0.44 ± 0.32. Oligodendrocytes were less strongly coupled to each other than astrocytes. Even cells immediately adjacent to one another were often uncoupled. Among coupled oligodendrocytes within 100 μm of each other, the average coupling ratio was 0.11 ± 0.1. Current passage between pairs of astrocytes and pairs of oligodendrocytes was nonrectifying. Application of 0.5 mM BaCl2 or 44.6 mM CsCl (substituted for NaCl) depolarized and increased the input resistance of astrocytes and oligodendrocytes. These ions also increased the coupling ratio in astrocyte pairs and oligodendrocyte pairs; this effect was rapid in onset and completely reversible. Ba++ and Cs+ appear to block resting K+ conductance in glia and probably increase the coupling ratio by increasing the effective length constant of the glial membrane without any direct effect on junctional resistance. In three cases, oligodendrocyte pairs that appear uncoupled in normal solution exhibited coupling in the presence of BaCl2 or CsCl. This suggests that oligodendrocytes may be widely coupled by junctions that provide only weak electrical interaction; such junctions might be important for the exchange of small metabolically active molecules. The strong electrical coupling among astrocytes, in concert with their K+‐selective membrane conductance, would provide for an electrical syncytium well designed to transport K+ away from areas of focal extracellular accumulation (i.e., the spatial buffer mechanism), and these cells, more than oligodendrocytes, may provide this function.
Model of potassium dynamics in the central nervous system
Authors: Odette Louis L. , Newman Eric A. 
Published: January 2005

AbstractA one‐dimensional numerical model of potassium dynamics in the central nervous system is developed. The model incorporates the following physiological processes in computing spatial and temporal changes in extracellular K+ concentration, [K+]o: (1) the release of K+ from K+ sources into extracellular space, (2) diffusion of K+ through extracellular space, (3) active uptake of K+ into cells and blood vessels, (4) passive uptake of K+ into a cellular distribution space, and (5) the transfer of K+ by K+ spatial buffer current flow in glial cells. The following tissue parameters can be specified along the single spatial dimension of the model: (1) the volume fraction and tortuosity of extracellular and glial cell spaces, (2) the volume fraction of the cellular distribution space, (3) rate constants of active uptake and passive uptake processes, and (4) glial cell membrane conductance. The model computes variations in [K+]o and current flow through glial cells for three tissue geometries: (1) planar geometry (the retina and the surface of the brain), (2) cylindrical geometry (tissue surrounding a blood vessel), and (3) spherical geometry (tissue surrounding a point source of K+). For simple sources of K+, the performance of the model matches that predicted from analytical equations. Simulations of previous ion dynamics experiments indicate that the model can accurately predict ion diffusion and K+ current flow in the brain. Simulations of electroretinogram generation and K+ siphoning onto blood vessels suggest that unanticipated K+ dynamics mechanisms may be operating in the central nervous system.
Glutamate opens Na+/K+ channels in cultured astrocytes
Authors: Sontheimer H. , Kettenmann H. , Backus K. H. , Schachner M. 
Published: January 2005

AbstractGlial cells from different brain regions and species are depolarized by the neurotransmitter glutamate. The depolarization or, if voltage‐clamped at the resting membrane potential, the inward current induced by glutamate could be due either to activation of receptor‐coupled ion channels or electrogenic uptake of the transmitter. In the present study we applied the patch‐clamp technique in the whole‐cell recording mode to analyze glutamate‐induced currents in cultured astrocytes from rat cerebral hemispheres. At the resting membrane potential, glutamate induced an inward current ranging from 40 to 300 pA. This current decreased in size with depolarization and reversed at about 0 mV. The resulting current‐to‐voltage curve was linear and depended strongly on the transmembrane Na+ but not on the Ca++ or Cl− gradient. In the presence of glutamate, current noise increased at potentials positive or negative from the reversal potential indicating that ionic channels are activated by glutamate. Both kainate and quisqualate mimicked the effect of glutamate. We conclude that glutamate opens a Na+/K+ channel in cultured astrocytes because of activation of a receptor which shares many properties with the neuronal kainate/quisqualate receptor.
Norepinephrine and cyclic adenosine 3′:5′‐cyclic monophosphate enhance a nifedipine‐sensitive calcium current in cultured rat astrocytes
Authors: MacVicar B. A. , Tse F. W. Y. 
Published: January 2005

AbstractWe employed two microelectrode current‐clamp and voltage‐clamp methods to examine the modulation of Ca++ channels by norepinephrine and cyclic AMP (cAMP) in cultured astrocytes from the rat cerebral cortex. Currents owing to Ca++ channels were maximized by replacing Ca++ with Ba++ in the extracellular solution and pharmacologically blocking K+ and Na+ currents. In current‐clamp experiments, we observed that norepinephrine, isoproternol (an agonist of β‐receptors for norepinephrine), or dibutyryl cAMP (dbcAMP, a membrane permeant analogue of cAMP) induced or enhanced slow Ba++‐dependent action potentials in the cells. In voltage‐clamp experiments, we confirmed that the slow action potentials were generated by a voltage‐activated and Ba++‐dependent inward current. This current was mediated by channels that resembled L‐type calcium channels (cf. McCleskey et al., Journal of Experimental Biology 124:177–190, 1986) in their voltage‐activation range, slow inactivation, and sensitivity to blockage by Co++, Cd++, and nifedipine. DbcAMP, or isoproterenol, enhanced the Ba++ current. Modulation of Ca++ channel function in glial cells could have functional implications.
Activation of excitatory amino acid receptors reduces thymidine incorporation and cell proliferation rate in primary cultures of astrocytes
Authors: Condorelli D.F. , Ingrao F. , Magri G. , Bruno V. , Nicoletti F. , Avola R. 
Published: January 2005

AbstractAddition of quisqualate (a heterocyclic analogue of glutamate) reduced [methyl‐3H]thymidine incorporation and cell proliferation in primary cultures of rat cortical astrocytes. The inhibitory action of quisqualate was mimicked by glutamate and ibotenate, whereas kainate, N‐methyl‐D‐aspartate (NMDA) and α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionate (AMPA) were inactive. These results suggest that activation of a specific class of excitatory amino acid receptors contributes to the regulation of growth and proliferation of glial cells in primary culture.
Astroglia‐released neurite growth‐inducing activity for embryonic hippocampal neurons is associated with laminin bound in a sulfated complex and free fibronectin
Authors: Matthiessen H. Peter , Schmalenbach Corinne , Müller Hans Werner 
Published: January 2005

AbstractNeurons from embryonic (E18) rat hippocampus were chosen to identify and characterize neurite growth‐stimulating proteins accumulating in serum‐free conditioned media (CM) obtained from primary or secondary cultures of cerebral astrocytes (less than 5% nonglial cells) using a quantitative cell culture bioassay. CM were fractionated by FPLC on an anion exchange column (Mono Q) and by gel filtration (Superose 6). Column fractions were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis, immunoblotting and enzyme‐linked immunosorbent assay (ELISA) using antibodies to laminin (LN) and fibronectin (FN). The neurite‐promoting activity (NPA) was tested by incubating aliquots of the eluted fractions with poly‐L‐lysine precoated glass coverslips prior to addition of neurons suspended in chemically defined medium. We provide evidence that the NPA in astroglial CM could be assigned mainly to a negatively charged, highly sulfated LN complex consisting predominantly of the B‐chains of LN and presumably a sulfated proteoglycan that was sensitive for chondroitinase and to a lower degree to heparinase degradation. In addition, a smaller proportion of the NPA was associated with uncomplexed LN and free FN. FN reached approximately 10 times the concentration of LN in astroglial CM. As revealed by immunofluorescence microscopy, both LN and FN are simultaneously expressed by cultured astrocytes; however, only the production of FN, measured by ELISA, increased during the time astrocytes were in culture, whereas the release of LN remained unchanged. We conclude that, besides the most active LN complex, FN bound to a polycationic matrix is able to induce neurite growth in hippocampal neurons in vitro.
Glial fibrillary acidic protein (GFAP) from goldfish: Its localisation in visual pathway
Authors: Nona S.N. , Shehab S.A.S. , Stafford C.A. , Cronly‐Dillon J.R. 
Published: January 2005

AbstractAn intermediate filament fraction, isolated from goldfish brain, contains a prominent protein having a molecular weight of 51 kDa. In normal goldfish visual pathway, this protein is present in tectum and tract, but not in optic nerve. A polyclonal antibody raised to this protein clearly labels ependymal glial profiles in tectum and parallel processes in the tract, whereas optic nerve is unlabelled; Müller fibres in the retina are also labelled. A similar, but less prominent, pattern of staining is observed with antibodies, raised elsewhere, against glial fibrillary acidic protein from human and porcine. These results suggest that the 51 kDa protein is a GFAP, demonstrate the heterogeneity of astrocytes in goldfish visual pathway, and are consistent with the idea that GFAP is well conserved in vertebrate phylogeny.
Electrophysiological characterization of a nicotinic acetylcholine receptor on leech neuropile glial cells
Authors: Ballanyi K. , Schlue W.‐R. 
Published: January 2005

AbstractIon‐selective double‐barrelled microelcetrodes were used to measure the activities of intracellular K+, Na+, Cl−, and H+ (a, a, a, pHi) and membrane potential (Em) in neuropile glial cells as well as extracellular K+ activity (a) in the neuropile of the leech, Hirudo medicinalis, during bath application of carbachol. As measured with conventional single‐barrelled microelectrodes, acetylcholine (ACh), nicotine, carbachol, tetramethylammonium (TMA), and choline elicited concentration‐dependent (10−6–5 × 10−3 M) transient membrane depolarizations of up to 60 mV amplitude whereas muscarine (10−6 –10−3 M) did not affect Em. α‐Bungarotoxin (10−7 M), decamethonium (10−5 M), d‐tubocurarine (5 × 10−5 M), and strychnine (5 × 10−5 M) blocked the carbachol depolarization by about 90%. Atropine (5 × 10−5 M) blocked the response by about 75%, whereas hexaethonium was only effective at millimolar concentrations.Average baseline levels of a in the neuropile and of a, a, and a in the neuropile glial cells were about 3, 70, 10, and 7 mM, respectively. During the carbachol depolarization a and a transiently increased, whereas a decreased. In contrast, a rise of a and a fall of a were observed during glial depolarizations in solutions with elevated K+ concentration. A increased during both the carbachol‐ and the K+ ‐induced depolarization. During carbachol, pHi transiently fell by about 0.2 units from its average baseline level of 6.9, whereas an alkalinization of small amplitude was observed in high‐K+ solutions. Bath‐applied choline, TMA, and decamethonium rapidly accumulated in the neuropile glial cells as intracellulary monitored with double‐barrelled microelectrodes filled with Corning K+ exchanger resin, which is highly selective for these agents.The results suggest that leech neuropile glial cells have a nicotinic ACh receptor coupled to a cation channel. It is hypothesized that this channel might also be permeable to choline, TMA, and decamethonium.
Expression of beta‐adrenergic receptors by astrocytes isolated from adult rat cortex
Authors: Salm A.K. , McCarthy Ken D. 
Published: January 2005

AbstractAstrocytes are the most numerous cell type in the central nervous system. When cultured, these cells express a wide variety of receptors for neurotransmitters. Nonetheless, it has yet to be firmly established that adult astrocytes in situ express receptors for neurotransmitters. In this report the technique of combined receptor autoradiography and immunocytochemistry has been applied to isolated astrocytes from adult animals to examine beta‐adrenergic receptor (β‐AR) expression by these cells. It is shown that fibrous and protoplasmic astrocytes isolated from adult rat cerebral cortices specifically bind the β‐AR ligand iodocyanopindolol and that this binding is inhibited by the β‐AR ligands propranolol and isoproterenol. These results indicate that at least two of the major morphological subtypes of adult astrocytes express β‐ARs.