bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving inferences from multiple methods
Authors: Shotland R. Lance , Mark Melvin M.
Published: January 2005

The use of multiple methods can result in an inferential challenge, though there are strategies to strengthen our inferences.
Large‐scale evaluation on a limited budget: The partnership experience
Authors: Shapiro Jonathan Z. , Blackwell David L.
Published: January 2005

A strategy is proposed and described for sharing evaluation responsibilities between client and evaluator, thereby leveraging the evaluator consultant's time and expertise and minimizing cost.
Direct cash low‐income housing assistance
Authors: Kennedy Stephen D.
Published: January 2005

Evidence 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

The 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.
Program managers: Victims or victors in the evaluation process?
Authors: Sonnichsen Richard C.
Published: January 2005

Federal program managers want evaluation information, but they also want evaluators to develop greater empathy and understanding.
Advice for the evaluated
Authors: Coffee Joseph N.
Published: January 2005

A collaborative approach to evaluation is aided by program managers' ability to determine their own readiness and the readiness of the evaluators.
Facilitating the development of health promotion programs: Recommendations for researchers and funders
Authors: Braverman Marc T. , Campbell Donald T.
Published: January 2005

Research on health promotion programming often functions under substantial external pressures, which can complicate the research enterprise.
Conceptualizing outcomes for health promotion programs
Authors: Best J. Allan , Brown K. Stephen , Cameron Roy , Smith Edward A. , MacDonald Marjorie
Published: January 2005

Health promoters need to change the ways in which they think about program outcomes as programs progress through the stages of research, development, and diffusion.
Uses of evaluation in a program to promote recovery from surgery
Authors: O'Connor Frederica W. , Cook Thomas D. , Devine Elizabeth C.
Published: January 2005

A critical multiplism evaluation approach guided the design, implementation, and assessment of a psychoeducational intervention for surgical patients.
Evaluation of training by trainers
Authors: Sanders Nicholas M.
Published: January 2005

A discussion of some obstacles that an evaluator of training confronts and of promising directions for more successful practice.
Methodology and justice
Authors: House Ernest R.
Published: January 2005

Evaluation methodology itself has sometimes led, in complex and subtle ways, to systematic injustices. The main source of error lies in our standard conception of causation, which is inadequate and incorrect.
An overview of AIDS modeling
Authors: Kaplan Edward H.
Published: January 2005

A variety of motivations exist for constructing mathematical models of the AIDS epidemic, including forecasting, scientific estimation of disease parameters, and policy analysis. This chapter discusses several different modeling approaches and their attendant uses, stressing the results most relevant to policy analysts and program evaluators.
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

Three 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.
AIDS prevention programs: The need for evaluation in the context of community partnership
Authors: Mantell Joanne E. , DiVittis Anthony T.
Published: January 2005

This chapter presents strategies for developing, implementing, and evaluating effective AIDS prevention programs within the confines of a partnership between an evaluator and a target community.
Inspections program evaluation within the U.S. Department of Defense Office of Inspector General
Authors: Vance William F.
Published: January 2005

The Inspector General has done a great deal to further management improvement efforts in the Department of Defense, utilizing inspections as one major tool in that effort.
Inspections as program evaluation: A partial overlap
Authors: Cordray David S.
Published: January 2005

OIG activities are evaluative in some senses, but they cover a narrow set of potential evaluative criteria that are needed to judge the worth of social programs. If OIGs are becoming main players in program evaluation, a dangerous trend is developing.
Public and private management of wastewater treatment: A comparative study
Authors: O'Toole, Jr. Laurence J.
Published: January 2005

Contracts 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.
Pathways into homelessness: An epidemiological analysis
Authors: Buckner John C.
Published: January 2005

An understanding of the causes of homelessness helps in designing and evaluating interventions.
Methodological issues in evaluating the national health care for the homeless program
Authors: Wright James D.
Published: January 2005

This chapter discusses the resolution of methodological issues in the evaluation of a health care program for homeless people.
Child and adolescent mental health services: Evaluation challenges
Authors: Rog Debra J.
Published: January 2005

Recent developments in the field of children's mental health, particularly the development of community‐based systems of care, are being used to improve the availability and effectiveness of services for children. This chapter highlights unique problems and challenges to evaluators studying these systems of care.
Measuring child, adolescent, and family service use
Authors: Burns Barbara J. , Angold Adrian , Costello Elizabeth J.
Published: January 2005

Currently, no method of classifying mental health services is accepted by all service sectors. Because classification is central to understanding the service delivery system for children and families, standardization of methods must be achieved.
Why program evaluation is important
Authors: General Accounting Office
Published: January 2005

The General Accounting Office transition report to the executive and legislative branches of government, Program Evaluation Issues, began with this short statement of the importance of evaluation in government.
The Office of Management and Budget: A continuing search for useful information
Authors: Wye Christopher G.
Published: January 2005

In the early 1980s, the Office of Management and Budget withdrew its support for program evaluation. Recently, it has articulated a clear understanding of the essential role of evaluation in government but has not advocated budget and staffing allocations to support it within the executive branch.
Evaluation in the General Services Administration: Adapting for greater efficiency and utility
Authors: Kriesberg Caleb
Published: January 2005

Over time, the General Services Administration evaluation functions have been decentralized throughout the management structure and have become more sharply focused on management issues, partly in response to cuts in budget and personnel.
The Congressional Research Service
Authors: Duffy Barbara Poitras
Published: January 2005

The Congressional Research Service provides analytical work on request to members of Congress. Much of this is short‐term information and background research, but some is substantial in‐depth research and analysis. Analysis is almost always based on secondary data and rarely employs sophisticated methodologies.
Aspects of investigative inquiry in evaluation
Authors: Smith Nick L.
Published: January 2005

A description of the characteristics of investigative inquiry can illuminate examples of evaluation practice that are increasingly investigative.
Using criminal investigations to improve evaluation results
Authors: Mangano Michael F.
Published: January 2005

Evaluators can use criminal investigation findings to focus and design program evaluations.
The role of investigation in program and policy development
Authors: Rog Debra J.
Published: January 2005

Investigative methods can play a role in the development of programs and policies as well as in their evaluation.
A quasi‐sampling theory of the generalization of causal relationships
Authors: Cook Thomas D.
Published: January 2005

This chapter discusses the generalization of causal relationships and offers an applied, meta‐analytical approach.
Implications for popular models of program evaluation
Authors: Scriven Michael
Published: January 2005

This chapter addresses a more sophisticated set of positions about program evaluation, all of which have been held by leading schools of thought in program evaluation at one time or another. The residue from these positions still is found in or widely supported by some departments and many professional evaluators.
School reform in Chicago: An overview
Authors: Clements Stephen K. , Kimberly Oliver A.
Published: January 2005

This chapter provides an introduction to and describes the background of the Chicago School Reform Act.
School reform: Chicago teachers and principals respond
Authors: Easton John Q. , Bennett Albert L.
Published: January 2005

This chapter describes the development and the results of two major surveys on Chicago school reform.
“And we will welcome them”: Reforming special education through Chicago school reform
Authors: Hehir Thomas
Published: January 2005

This chapter examines special education practices within Chicago school reform.
Reform and the quality of education in Chicago
Authors: Niemiec Richard P. , Walberg Herbert J.
Published: January 2005

This chapter examines achievement, attendance, and other indicators of quality education.
Critical multiplism, meta‐analysis, and generalization: An integrative commentary
Authors: Figueredo Aurelio José
Published: January 2005

This chapter examines the conceptual relationships between the research strategy of critical multiplism and the methods of meta‐analysis and generalizability theory for quantitative data synthesis.
Qualitative plus/versus quantitative: The last word
Authors: Smith Mary Lee
Published: January 2005

Neither methodological correctness nor paradigm purity offers an appropriate framework for evaluation practice.
Common implementation issues in three large‐scale social experiments
Authors: Stevens Sally J.
Published: January 2005

Issues encountered when using random assignment in social service research are examined. Examples from three social programs are used to illustrate the problems that were encountered and the solutions developed.
The political roots of misuse of evaluation
Authors: Palumbo Dennis J.
Published: January 2005

Two types of evaluation misuse are described: misuse by a client who is politically committed to continuing or expanding a program regardless of the results; and misuse by an evaluator who changes results in order to satisfy the client.
Use and abuse of internal evaluation
Authors: Duffy Barbara Poitras
Published: January 2005

Although there are many advantages of internal evaluation, there are also disadvantages, the most serious of which is potential misuse by managers who want evaluations to appear to objectively support decisions that have already been made.
The misuse of evaluation in educational programs
Authors: Dial Micah
Published: January 2005

Misuse of an evaluation occurs when the process or findings are altered to promote one's self‐interests; this generally occurs when educational programs have difficulty demonstrating their impact on the target population.
Misusing program evaluation by asking the wrong question
Authors: Posavac Emil J.
Published: January 2005

Limited understanding of the purposes of program evaluation can lead to misuse; evaluators must educate clients and stakeholders so that evaluation designs are refined to produce useful information.
Electrical coupling between astrocytes and between oligodendrocytes studied in mammalian cell cultures
Authors: Kettenmann Helmut , Ranson Bruce R.
Published: January 2005

The 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

A 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

Glial 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

We 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

Addition 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

Neurons 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

An 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

Ion‐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

Astrocytes 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.
Glutamate receptor‐linked changes in membrane potential and intracellular Ca2+ in primary rat astrocytes
Authors: Enkvist M.O. Kristian , Holopainen Irma , Åkerman Karl E.O.
Published: January 2005

Kainate‐, quisqualate‐ and glutamate‐induced depolarization and mobilization of intracellular Ca2+ was determined in primary cultured astrocytes using the fluorescent probes DiBa‐C4‐(3) and fura‐2, respectively. All three receptor agonists depolarized the cells in a Na+‐dependent manner and increased the intracellular Ca2+ concentration. The glutamate‐ and quisqualate‐induced increase in cytosolic Ca2+ was only partially inhibited by removal of extracellular Ca2+, whereas the response to kainate was totally dependent on extracellular Ca2+. The mechanisms for depolarization and increases in cytosolic Ca2+ appeared to be independent of each other, as extracellular Ca2+ removal or intracellular Ca2+ buffering with entrapped BAPTA did not affect the depolarization. Removal of extracellular Na+ did not affect the agonist‐induced increase in Ca2+. If quisqualate was added after kainate, the cells were hyperpolarized in a Ca2+‐ and K+‐dependent manner. This could be due to effects on a Ca2+‐dependent K+ channel, the effects of which are normally hidden by the greater effect on Na+ channels as a response to quisqualate.
C17, a retrovirally immortalized neuronal cell line, inhibits the proliferation of astrocytes and astrocytoma cells by a contact‐mediated mechanism
Authors: Weinstein David E. , Shelanski Michael L. , Liem Ronald K. H.
Published: January 2005

We have investigated the ability of various cell lines to effect contact‐mediated inhibition of astrocytic cells. Of the lined tested, only C17, a mouse cell line from postnatal day 0 cerebellum immortalized by infection with a retroviral construct containing the avian myc gene, and U251, a human astrocytoma line, were able to inhibit the proliferation of astrocytic cells. With co‐cultured with either primary astrocytes from rat cerebellum or the U251 line, the C17 cells induced a rapid cessaion of glial cell division as well as complex astrocytic process extension. The effects on glial mitosis were cell‐dose‐dependent, with ten C17 cells/glial cell being the optimal ratio. At this ratio [3H]thymidine incorporation into the U251 cells was reduced by greater than 80% and there was a virtual stasis in glial cell number at 48 hours. Fixed C17 cells as well as partially purified C17 membranes were also potent inhibitors of astrocytic proliferation, suggesting that the gliastatic effect of the C17 cell line is membrane associated. However, neither of these preparations induced astrocytic process formation. We also confirmed earlier reports that U251 cells inhibited their own proliferation in a density‐dependent manner but at a lower fficiency than the C17 cells.
Electrophysiological measurements of volume changes in leech neuropile glial cells
Authors: Ballanyi K. , Grafe P. , Serve G. , Schlue W.‐R.
Published: January 2005

Double‐barrelled microelectrodes, sensitive to quaternary ammonium ions, were used for simultaneous measurements of the intracellular free concentrations of choline ([Ch]i) or tetramethylammonium [TMAi] as well as membrane potential (Em) in neuropile glial cells of the leech, Hirudo medicinalis. Bath application of Ch or TMA (5 mM, 1 min) resulted in a transient membrane depolarization accompanied by a long‐ lasting (0.5–1 h) intracellular accumulation of these compoundsto levels of between 5 and 15 mM. Changes in [Ch]i or [TMA]i were used for the calculation of changes in relative cell volume. Elevation of the extracellular K+ concentration ([K+]e) from 4 to 9,15,21,27.5, or 40 mM elicited a membrane depolarization and a reversible cell swelling by about 7.5,14, 18.5, 27 and 50%, whereas reduction of [K+]e to 1.5 mM as well as bath application of serotonin (5‐HT) produced a membrane hyperpolarization and a concomitant shrinkage by about 6 and 14.3%, respectively. The measured alterations in cell volume were compared with calculated data based on the assumption of an osmotic equilibrium disturbed by potential‐dependent changes of the intracellular Cl− concentration. The results indicate, that K+‐ and serotonin‐induced changes in the cell volume of the neuropile glial cells are due to passive KCl and water fluxes.
Stimulation of thromboxane release from primary cell cultures derived from human astrocytic glioma biopsies
Authors: Murphy Sean , Welk Greg , Thwin Soe Soe
Published: January 2005

Stimulation of primary cultures of rat astrocytes with appropriate agents results in the mobilization of arachidonic acid from intracellular lipid pools and the synthesis of eicosanoids. Thromboxane A2 is one of the major prostanoids released upon stimulation with calcium ionophore, phorbol esters, and ATP; but a number of other predicted effectors are inactive. In an attempt to understand the pathophysiological significance of eicosanoid release from astrocytes, primary cultures have been derived from human astrocytic glioma biopsies. The majority of cells in the cultures expressed glial fibrillary acidic protein (GFAP), frequently in conjunction with vimentin and fibronectin. Cell sorting revealed that a significant proportion of cells in the cultures from the high‐grade (malignant) tumors expressed epidermal growth factor receptor, indicative of neoplastic cells. Both effective and ineffective agents in rat cultures were tested for their ability to stimulate release of thromboxane from these gliomas, and also from cultures of medulloblastoma and ependymoma which contained significant numbers of GFAP‐positive cells. Only cells from the high‐grade tumors released thromboxane in response to the known effective stimuli. While the muscarinic agonist carbachol was ineffective, norepinephrine evoked thromboxane release from malignant astrocytomas. These data show that cells derived from malignant human gliomas retain the ability to release thromboxane upon stimulation and suggest that a transformation in receptor coupling might accompany neoplasia, such that the cells now respond to a previously ineffective agonist.
Investigation of dysmyelinogenesis in caprine β‐mannosidosis: In vitro characterization of oligodendrocytes
Authors: Boyer Philip J. , Lovell Kathryn L.
Published: January 2005

Central nervous system myelin deficiency is a consistent feature of caprine β‐mannosidosis, and autosomal recessive neurovisceral lysosomal storage disease. To investigate the possibility of an intrinsic oligodendrocyte defect in β‐mannosidosis, oligodendrocyte‐enriched glial cultures from the cerebral hemisphere white matter of two affected and six control goats were compared with respect to culture yield and morphology. Fewer oligodendrocytes were cultured per gram of white matter from affected animals than from control animals. Galactocerebroside‐positive oligodendrocytes from all animals were similar morphologically at all stages of culture by phase contrast and fluorescence microscopy. These findings are consistent with in vivo morphological observations and suggest that differentiated oligodendrocytes from affected animals do not show morphological abnormalities in culture. However, increased numbers of galactocerebroside‐negative bipolar cells, which may be glial progenitor cells, were present in cultures from affected animals. This observation suggests the possibility of a defect in differentiation to mature oligodendrocytes, with persistence of the undifferentiated glia during late stages of development.
Sorbitol pathway activity and utilization of polyols in astroglia‐rich primary cultures
Authors: Wiesinger Heinrich , Thiess Ulrike , Hamprecht Bernd
Published: January 2005

Astroglia‐rich rat primary cultures can be grown in a glucose‐free medium containing 25 mM sorbitol. After 10 days under these conditions, the total number of cells and DNA content are reduced to 50–60% of those of control cultures, but remain constant thereafter. The specific activities of the sorbitol pathway enzymes, sorbitol dehydrogenase and aldose reductase, are increased 2.5‐fold and unchanged, respectively, if the cells are grown in the presence of sorbitol instead of glucose. Treatment with the aldose reductase inhibitor sorbinil does not decrease the number of cells cultured in the glucose‐free medium in the presence of sorbitol. Fructose is as good a substrate for the glial cells as sorbitol, whereas out of a number of other polyols tested only xylitol can support the primary cultures for more than 3 days. Neither neuron‐rich rat brain primary cultures nor rat glioma cells can be cultured in the sorbitol‐containing medium in the absence of glucose. With sorbitol substituting for glucose in the culture medium, effects of glucose deprivation on cellular functions like sugar transport and metabolism can be investigated in glial cultures for an extended period of time.
Remote astrocytic response as demonstrated by glial fibrillary acidic protein immunohistochemistry in the visual cortex of dorsal lateral geniculate nucleus lesioned rats
Authors: Hajós Ference , Kálmán Mihály , Zilles Karl , Schleicher Axel , Sótonyi Peter
Published: January 2005

The reaction of astroglia was investigated after unilateral destruction of the dorsal lateral geniculate nucleus in the primary visual cortex of adult albino rats. The destruction of the dorsal lateral geniculate nucleus was performed by stereotaxic injections of ibotenic acid, and the location was verified in Nissl stained sections in each animal. Electron microscopic observations demonstrated the presence of degenerating axon terminals surrounded by hypertrophic astroglial processes mainly in layers III and IV of the ipsilateral primary visual cortex. The ipsilateral (impaired) and contralateral (control) sides of the primary visual cortex showed light microscopically a clearly differing appearance and distribution of glial fibrillary acidic protein (GFAP) immunoreactivity 7 to 11 days after the unilateral injection of ibotenic acid into the dorsal lateral geniculate nucleus. Whereas the control side of the primary visual cortex showed GFAP staining only in the subpial zone of layer I and close to the white matter, all layers of the impaired cortex showed an intense GFAP immunoreactivity. The increase in immunoreactivity was confined to the primary visual cortex. The extent of and increase in immunoreactivity was corroborated by image analysis. These findings were interpreted as a localized hypertrophy of astroglia caused by the anterograde degeneration of geniculocortical terminals. This hypertrophy is accompanied by an increase in GFAP, which may represent the stabilization of the cytoskeleton of newly formed glial processes involved in the rearrangement of the impaired neuropil.
Müller cell changes precede vascularization of the pigment epithelium in the dystrophic rat retina
Authors: Roque Rouel S. , Caldwell Ruth B.
Published: January 2005

In the Royal College of Surgeons rat with inherited retinal dystrophy, photoreceptor cell degeneration is accompanied by retinal pigment epithelial (RPE) cell alterations and Müller cell changes such as increased expression of glial fibrillary acidic protein (GFAP). Vascular changes such as vascularization of the RPE, vascular proliferation, and formation of vitreoretinal membranes (VRMs) are observed later. To study the relationship of Müller cell changes to the vascular alterations in the dystrophic retina, we used immunoperoxidase techniques and antibodies against GFAP and vimentin. Our study showed that during photoreceptor degeneration, Müller cells expressed small amounts of GFAP. As degeneration progressed, GFAP expression increased and morphological alterations occurred in Müller cells. Müller cell apical processes extended and proliferated in the subretinal space and contacted the apical surface of duplicated RPE cells. Later, GFAP reactive fibers surrounded retinal vessels apposed to the RPE. As the vessels became enmeshed within the RPE, the GFAP‐positive perivascular processes disappeared. Eventually, the RPE‐associated vessels became displaced into the inner retina where VRMs were sometimes observed. Immunoblots showed increased GFAP in dystrophic as compared with control retinas. Studies of vimentin distribution in the dystrophic retina showed results similar to the GFAP study. Moreover, the vimentin study suggested increased number of Müller cell processes in the dystrophic as compared with control retinas. The close temporal and anatomical relationships among Müller cell, RPE, and vascular changes in the dystrophic rat suggest a role for Müller cells in retinal neovascularization and proliferative retinopathy.
Norepinephrine‐evoked calcium transients in cultured cerebral type 1 astroglia
Authors: Salm A. K. , McCarthy Ken D.
Published: January 2005

We have used the CA++ indicator dye fura‐2 AM and computerized imaging systems to investigate adrenergic regulation of intracellular calcium in cultured cerebral type 1 astroglia. We have found that norepinephrine (NE) and other adrenergic agonists stimulate increases in intracellular calcium in over 80% of type 1 astroglia tested. A wide range in effective NE concentrations was seen. With sufficient agonist concentrations the calcium response was biphasic, exhibiting an initial sharp peak followed by a sustained calcium elevation. This secondary component was sensitive to reductions in extracellular calcium concentrations and dependent on the continued presence of agonist. Pharmacological studies indicated that astroglial calcium responses were mediated by α1‐ and α2‐adrenergic receptors. At times these two receptor subtypes appeared to underlie calcium responses by the same cells, whereas other cells only responded to stimulation of one or the other subtypes of α‐adrenergic receptor. Finally, we have also observed spontaneous and agonist‐evoked oscillations in astroglial calcium levels. The major findings of these studies indicate that 1) astroglial cells respond to α‐adrenergic receptor stimulation with increased intracellular calcium, 2) these responses can be mediated by α1‐and/or α2‐adrenergic receptors, and 3) subpopulations of cerebral type 1 astroglia exist with respect to α‐adrenergic receptor expression.
Retinal neurite growth on astrocytes is not modified by extracellular matrix, anti‐L1 antibody, or oligodendrocytes
Authors: Ard March D. , Bunge Mary Bartlett , Wood Patrick M. , Schachner Melitta , Bunge Richard P.
Published: January 2005

Two factors that may influence the course of axonal regeneration in the central nervous system (CNS) are extracellular matrix (ECM) and cell surface molecules that may enhance or inhibit neurite outgrowth. Whereas cultured astrocytes have been reported to be a good substratum for neurite outgrowth, there is recent evidence that cultured oligodendrocytes are inhibitory. To test the influences of (1) ECM components, (2) the L1 adhesion molecule, and (3) the inhibitory potential of mature oligodendrocytes in the astrocytic environment, we have utilized a culture system in which neurites from embryonic rat retina grow vigorously on astrocyte monolayers. The major ECM components were assembled in neonatal rat cortical astrocyte‐retina co‐cultures only when the medium contained serum. In electron microscopic studies of serum containing cultures, retinal neurites were seen to be related to astrocyte surfaces but rarely were found in contact with ECM; in serum‐free medium the association between neurites and astrocytes was similar. In addition, the growth of neurites was vigorous whether ECM was present or absent. Presence of antibodies against the cell surface adhesion molecule L1 did not inhibit retinal neurite elongation on glial fibrillary acidic protein‐positive astrocytes, When oligodendrocytes from adult rat spinal cord were combined with the astrocytes, retinal neurites grew as well on the mixed glial population as on astrocytes alone. Immunostaining for galactocerebroside showed many oligodendrocyte processes to be aligned in the direction of neurite growth, suggesting association between the two cell types. This association was verified by electron microscopy. Furthermore, retinal explants extended neurites among myelin basic protein‐positive oligodenrocytes cultured without astrocytes.

Thus, the astrocyte surface is a strong promoter of neurite growth from embryonic rat retina. This growth did not depend upon either ECM or the L1 adhesion molecule. Because neurites grew on astrocytes in the presence of mature oligodendrocytes or among oligodendrocytes alone, we conclude that oligodendrocytes do not inhibit neurite growth under certain conditions.
GABA release triggered by the activation of neuron‐like non‐NMDA receptors in cultured type 2 astrocytes is carrier‐mediated
Authors: Gallo Vittorio , Patrizio Mario , Levi Giulio
Published: January 2005

Kainate (KA), quisqualate (QA), and α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA) stimulated γ‐aminobutyric acid [3H]γ‐aminobutyric acid (GABA) release from cultured cerebellar type 2 astrocytes and from their bipotential precursors. The evoked release was prevented by the antagonist 6‐cyano‐2,3‐dihydroxy‐7‐nitro‐quinoxaline (CNQX). AMPA and QA applied together with KA at concentrations around or above their EC50s (20–50 μM) antagonized the stimulatory effect of KA on [3H]GABA release. On the other hand, the releasing action of KA was potentiated by concentrations of QA in the low micromolar range (2–5 μM), particularly when the concentration of KA was at the borderline of effectiveness (10 μM). KA and QA did not elevate intracellular cyclic GMP levels in astrocyte cultures, although guanylate cyclase was present in both type 2 and type 1 astrocytes. The inability of KA to elevate cyclic GMP levels in astrocytes was the only major difference in the behavior of this glutamate agonist between astroglial and neuronal cultures. The GABA transport inhibitor nipecotic acid or replacement of NaCl with LiCl abolished [3H]GABA uptake and also KA‐ and QA‐induced release of preaccumulated [3H]GABA. Therefore, [3H]GABA was released from type 2 astrocytes and their progenitors through its Na+‐dependent transport system, operating in an outward direction when the cells were depolarized by non‐NMDA receptor agonists.
Effect of thyroid deficiency on glial fibrillary acidic protein (GFAP) and GFAP‐mRNA in the cerebellum and hippocampal formation of the developing rat
Authors: Faivre‐Sarrailh Catherine , Rami Abdelhaq , Fages Christiane , Tardy Marcienne
Published: January 2005

The concentrations of glial fibrillary acidic protein (GFAP) and its encoding mRNA in the cerebellum and hippocampal formation were assayed during the development of normal and hypothyroid rats. Neonatal hypothyroidism induced a significant reduction in the GFAP concentration in both regions from day 14. The reduction was especially marked on day 35 in the cerebellum (−43%) and the hippocampal formation (−55%). The immunocytochemical study of vimentin showed that the developmental disappearance of this protein from the Bergmann and internal astroprcytes is greatly delayed in the cerebellum of the hypothyroid rats. The reduction in GFAP concentration together with the delayed vimentin‐GFAP transition could explain how astrocyte morphogenesis is impaired by neonatal thyroid deficiency.

The GFAP‐mRNA concentration in the hippocampal formation was reduced throughout the development of thyroid‐deficient rats, while the GFAP‐mRNA concentration in the cerebellum first increased between birth and day 14 to reach a peak well above the normal value (+78%) and decreased thereafter to reach 53% of the normal value by day 35. This transient increase in the cerebellar GFAP‐mRNA concentration may be related to the astroglial hyperplasia that occurs in these animals. The difference between the developmental profile of GFAP and its encoding mRNA, especially under pathological conditions, indicates that two distinct mechanisms control the synthesis or stability of the protein and its messenger RNA, as was previously found in the forebrain of the developing normal rat.
Characterization of glycosaminoglycans produced by primary astrocytes in vitro
Authors: Johnson‐Green P. C. , Dow K. E. , Riopelle R. J.
Published: January 2005

Quantitative biosynthetic studies with cultures highly enriched for glial fibrillary acidic protein (GFAP+) cells of neonatal mammalian brain demonstrated production of four proteoglycans: hyaluronate (HA), heparan sulphate (HS), chondroitin sulphate (CS), and dermatan sulphate (DS). The glycosaminoglycans were present in cell conditioned medium and in the cellular compartment. There were qualitative differences in the subcellular disposition of the various proteoglycans. The ratio of HS to CS/DS in cell extracts was 1:1, while in medium this ratio was 1:6. All of the glycosaminoglycans were associated with core proteins that were integral to the cell membrane and associated with the cell surface by non‐covalent interactions involving glycosaminoglycans. Less than 20% of the HS was non‐covalently associated with the astrocyte cell surface reflecting in part the proportionately smaller amounts of this proteoglycan released to astrocyte conditioned medium. HS released to medium was undersulphated relative to that associated with cells.

The astrocyte can contribute proteoglycans to the extracellular milieu and displays cell surface proteoglycans that have the potential to provide appropriate substrates for neuron adhesion, process extension, and other cell‐cell interactions.