bluuebunny/crossref_metadata_2025 huggingface dataset:
A refractory period for the heart rate response in infant visual attention
Authors: Casey Betty Jo , Richards John E.
Published: January 2005

A refractory period for the heart rate (HR) response of 14‐, 20‐, and 26‐week‐old infants to second stimulus onset and primary stimulus offset during termination of visual attention was investigated. A stimulus that elicited a significant HR deceleration was presented. Following the return of HR to prestimulus level, a second stimulus occurred or the first stimulus ended at time delays of 0, 3, 6, and 9 s. If the second stimulus occurred at 0 or 3 s after HR returned to its prestimulus level, the HR response was smaller than the initial HR orienting response (OR). A usual HR OR resulted by waiting 6–9 s after the return of HR to prestimulus level. A significant offset response occurred only for the 6‐sec delay. Active inhibition of vagal cardiac activity during attention termination may cause the observed refractory period in the HR response, which appears to last from 3–6 s following sustained attention.
Time course of the effect of maternal deprivation on the hypothalamic‐pituitary‐adrenal axis in the infant rat
Authors: Levine Seymour , Huchton David M. , Wiener Sandra G. , Rosenfeld Patricia
Published: January 2005

Prologed (i.e., 24‐hr) maternal deprivation leads to a marked disinhibition of the infant rat's adrenocortical response to stress and/or ACTH. In the following study we examined the time course over which these effects develop. Pups were maternally deprived for varying lengths of time (i.e., 0, 2, 4, 8, & 24 hr); at the end of this period, corticosterone (CORT) secretion in response to stress (novelty or novelty plus saline injection) and ACTH injection was measured. Basal levels of CORT increased progressively over time in 7‐and 11‐(but not 3‐) day‐old pups. CORT release in response to stress followed a similar pattern. In contrast, ACTH injection resulted in marked increases in CORT levels regardless of the length of maternal deprivation in 3‐day‐old animals; at older ages, however, 24 hr of deprivation led to a much larger increase. These findings support the hypothesis that the hypothalamic‐pituitary‐adrenal axis of the neonatal rat is subject to maternal regulation.
The biphasic effect of morphine on odor conditioning in neonatal rats
Authors: Randall Christopher K. , Kraemer Philipp J. , Dose John M. , Carbary Timothy J. , Bardo Michael T.
Published: January 2005

Three experiments examined the dose‐dependent biphasic effect of morphine on odor conditioning in neonatal rats. In Experiment 1, a single pairing of an odor and a low dose of morphine (0.5 mg/kg) in 5‐day‐old rats produced an odor preference, relative to an unpaired control group. In Experiment 2, pairing an odor with a high dose of morphine (2.0 mg/kg) produced an odor aversion, relative to an unpaired control group. A third experiment compared performance of a group given odor and morphine (2.0 mg/kg) paired to that of two unpaired groups: one given morphine 24 hr prior to and the other 24 hr after odor exposure. The paired group showed an odor aversion relative to both of the unpaired groups, which did not differ. The latter finding suggests that even if morphine metabolism is incomplete after 24 hr, behavior is unaffected. These results are discussed in reference to the functional development of the opioid system in rats © 1992 John Wiley & Sons, Inc.
Developmental thermoregulatory deficits in prenatal ethanol exposed long‐ and short‐sleep mice
Authors: Gilliam David M. , Kotch Lori E.
Published: January 2005

Sensitivity to alcohol may influence the severity of prenatal alcohol effects. To examine this hypothesis, the ontogeny of thermoregulation was measured in prenatal ethanol exposed offspring of mice selected for differences in alcohol sensitivity. Pregnant long‐sleep (LS) and short‐sleep (SS) mice were exposed to 3 or 4 g/kg ethanol or an isocaloric amount of maltose‐dextrin twice per day from day 7 through 18 of pregnancy. Doses were given six hours apart via gavage. Nonintubated lab chow controls were included for both genotypes. Offspring were fostered at birth to lactating mice of an outbred strain. Offspring temperatures were measured at 0, 60, and 120 min away from the nest on alternating days from 7 through 21 days of age. LS and SS offspring prenatally exposed to the high ethanol dose showed lower temperatures at the 60 and 120 min time points on each day of testing compared to all other treatment groups. Temperatures of offspring prenatally exposed to the low ethanol dose did not differ from controls. These results suggest a relatively steep dose‐response curve for thermoregulatory deficits in LS and SS offspring prenatally exposed to alcohol. Genetically‐based alcohol sensitivity did not influence the effects of prenatal alcohol exposure on this response © 1992 John Wiley & Sons, Inc.
Visual discrimination and recognition of facial expressions of anger, fear, and surprise in 4‐ to 6‐month‐old infants
Authors: Serrano Juan M. , Iglesias Jaime , Loeches Angela
Published: January 2005

On the assumption that the ability to discriminate facial expressions has adaptive value to infants during early social exchanges, ethologically based theorists have argued that this ability is innate. Guided by this perspective, we investigated the ability of infants, 4–6 months old to recognized and discriminate facial expressions of anger, fear, and surprise. Results obtained with an infant‐controlled habituation‐recovery procedure showed that infants both discriminated and recognized these expressions when portrayed by several adult female models. In addition, infants spent more time looking at expressions of anger and surprise that at fear expressions. These results suggest that infants can abstract configurations of features that give affective meaning to facial expression. It is suggested that the differences in habituation to each expression might be the result of their distinct functional signification for the infant. © 1992 Wiley & sons. Inc.
The ontogeny of phencyclidine‐induced wall climbing and locomotor activity
Authors: Scalzo Frank M. , Burge Lora J.
Published: January 2005

Wall climbing behavior is an age‐specific behavior that is elicited during postnatal Days 7 through 17 by various stimuli that include heat, odors, shock, and the catecholaminergic agonists apomorphine, amphetamine, and clonidine. In a previous study, a significant amount of wall climbing behavior was observed during ataxia and activity testing following phencyclidine (PCP) administration in Day 19 but not Day 40 rat pups. The present study describes the ontogeny of PCP‐induced wall climbing behavior and locomotor activity. Frequency and duration of wall climbing bouts and locomotor activity were recorded on Days 5, 12, 19, 26, 33, or 40 following PCP treatment. On Day 12, all doses of PCP induced significant amounts of wall climbing behavior. A similar pattern of results was observed on Day 5 although these effects were not statistically significant. After Day 12, PCP‐induced wall climbing behavior declined precipitously. PCP increased locomotor activity at all ages tested with maximum activities observed on Day 19. These results demonstrate that PCP‐elicited wall climbing behavior follows an ontogenetic profile similar to that previously reported for other stimuli and that there are robust ontogenetic differences in the locomotor response to PCP. © 1992 Wiley & sons. Inc.
Social and nutritional influences on the feeding of ring dove squab
Authors: Iskrant Katharine R. , Balsam Peter D
Published: January 2005

The effects of food deprivation on ring dove squabs′ begging and pecking was examined during the period of transition from dependent to independent feeding. Food‐deprived squabs begged more, pecked more, and were fed more by their parents than nondeprived squabs. When deprived, young squab primarily beg for food and older squab primarily peck. This difference may arise from the relative efficiencies of the two feeding responses at different ages. Additionally, parental state exerted control over the amount the squab pecked and begged. Parental food deprivation affected squab pecking, probably because hungry parents pecked more themselves and fed squabs less. Squab begging was not affected by parental food deprivation. However, parental separation from squab affected squab begging, as parents previously without squab were more likely to feed begging squab than were parents who were not separated from squab. Parental separation from squab did not affect squab pecking. The changes in the endogenous and exogenous controls of squab feeding allow for a great deal of plasticity in the transition from dependent to independent feeding.© 1994 John Wiley & Sons, Inc.
Behavioral profiles of adult rats in a difficult food supply social situation, related to certain early behavioral features
Authors: Deviterne Dominique , Peignot Patricia , Krafft Bertrand
Published: January 2005

Behavioral profiles of male rats were defined in nine intralitter groups of six individuals at various stages of their development: (a) at pup stage in individual situations (uncomfortable positions) and social situations (removal away from the mother), and (b) at adult stage in a difficult food supply social situation (complete immersion of the food access way). The male population was split into two sets, both at pup stage (the most and the least swift and efficient of each group to overcome uncomfortable situations), and at adult stage (carriers and noncarriers of food in each group tested). Our results showed an important relation between these pup and adult behavioral profiles: the swiftest and most efficient individuals of a group at pup stage adopted more often a food carrier behavioral profile at adult stage. Assumptions about the predictive value of some behavioral features of a young rat in regard to its adult behavioral profile are discussed.© 1994 John Wiley & Sons, Inc.
e‐VALUE‐ation
Authors: Stone James C.
Published: January 2005

The phenomenologist is both a participant observer and a judge who ultimately uses his values, clinical experience, and emotional reactions as valid data in evaluating the worth of a program.
Ethics in practice
Authors: Perloff Evelyn , Perloff Judith K.
Published: January 2005

Selected evaluation studies provide an empirical check of ethical practices.
Evaluation researchers: Disciplinary training and identity
Authors: Sechrest Lee
Published: January 2005

Should evaluation research move toward the status of an independent field or discipline or should it be nurtured as a subspecialty within academic and problem areas? Since the field is new, it may be too early to settle on any single model for training.
What can we learn about change in organizations?
Authors: Cline Hugh F. , Sinnott Loraine T.
Published: January 2005

Methods useful in identifying and assessing outcomes of relatively simple programs may not be practical or appropriate for complex programs and systems. Comparative case study methods are recommended for dealing with such global outcomes of planned organizational change.
Disease patterns, epidemiology, and evaluation: An evolutionary perspective
Authors: Dever G. E. Alan , Rousseau Rebecca H. , Houser Frank M.
Published: January 2005

Although the evolution of health program evaluation should keep pace with the parallel evolution of disease patterns and epidemiology, it in fact lags behind.
Evaluating effectiveness in computing centers
Authors: Varanelli, Andrew
Published: January 2005

The goal model is appropriate for evaluating effectiveness in computing centers and, by extension, other service organizations.
Emerging evaluation methods in mental health services
Authors: Windle Charles , Flaherty Eugenie Walsh
Published: January 2005

Mental health values are now underrepresented in evaluation methods for mental health programs, and emerging evaluation methods differ widely in their promise for addressing this situation.
Where angels fear to tread and why
Authors: Berk Richard A.
Published: January 2005

The dilemma inherent in all formal standards results from the tension between maintaining quality control, on the one hand, and constraining creativity, on the other.
Legal and government implications of the ERS standards for program evaluation
Authors: Cahn Jerry
Published: January 2005

Adoption of the Standards by ERS requires consideration of legal and government implications of adopting codes of conduct in general and the Standards in particular.
Evaluation and reform
Authors: Cohen David K.
Published: January 2005

If government chooses to take account of competing views in social program evaluation, it can get a better result by encouraging these competing views to find their own voices, rather than speaking through the government's chosen instrument.
Management and organization of an evaluation unit in a state education agency
Authors: Peck Hugh I. , Triplett Suzanne E.
Published: January 2005

The Bureau of Evaluation, created three years ago by the Louisiana Department of Education, has established policies and procedures that ensure use of evaluation findings by both policy makers and program administrators.
Contractor evaluation for the federal government
Authors: Levine Robert A.
Published: January 2005

What kind of contract evaluation firm is most likely to survive and profit in Washington today? How can such firms fill the government's needs for valid and objective evaluation information at minimum cost?
The occupational role of the evaluation research manager
Authors: Dentler Robert A.
Published: January 2005

The functions and career paths of evaluation research managers, their duties and generic styles, and some indicators of performance quality are outlined, and a better way to assess and select them in the future is proposed.
Quantitative versus interpretive: The problem of conducting social inquiry
Authors: Smith John K.
Published: January 2005

Discussions of the differences between quanititative and interpretive approaches to social inquiry have been engaged in since the late nineteenth century, even though there is still a need to clarify what is specifically involved.
The evaluation taboo
Authors: Scriven Michael
Published: January 2005

Evaluation is the one indispensable activity of all science.
The importance of adhering to details of the Total Design Method (TDM) for mail surveys
Authors: Dillman Don A. , Dillman Joye J. , Makela Carole J.
Published: January 2005

The empirical effects of adherence to details of the Total Design Method approach to the design of mail surveys is discussed.
The stages of mailed questionnaire returning behavior
Authors: Lockhart Daniel C.
Published: January 2005

The editor describes stages at which the evaluator can reduce the resistance of potential respondents to mailed questionnaires.
Impact analysis using an integrated data base: A case study
Authors: Bowering David J.
Published: January 2005

This case study describes how path analysis and causal modeling were used to assess the impact of federal R&D spending on Ph.D. production at leading research universities. The data base was constructed by integrating five years of data from seven different surveys into a single data base.
Research methods for evaluating the new information technologies
Authors: Johnston Jerome
Published: January 2005

Characteristics of the new information technologies have implications for both summative and formative evaluation. The instability of most technologies, coupled with their novelty for most users, calls into question the value of experimental summative studies, and the interactive character of many instructional technologies challenges the traditional formative paradigm. Case studies and field experiments can help to cope with this situation.
Cultural considerations for evaluation consulting in the Egyptian context
Authors: Seefeldt F. Michael
Published: January 2005

Adapting the requirements for good evaluation to consulting in Egypt poses a cultural challenge that sometimes seems no less great than that of building the Suez Canal.
The teaching of evaluation in schools of management
Authors: Perloff Robert , Rich Robert F.
Published: January 2005

This chapter explores the issues faced by teachers who want to integrate program evaluation into the curriculum of schools of management.
Relabeling internal and external validity for applied social scientists
Authors: Campbell Donald T.
Published: January 2005

Confusion about the meaning of validity in quasi‐experimental research can be addressed by carefully relabeling types of validity. Internal validity can more aptly be termed “local molar causal validity.” More tentatively, the “principle of proximal similarity” can be substituted for the concept of external validity.
Conceptual and action heuristics: Tools for the evaluator
Authors: McClintock Charles
Published: January 2005

Two types of program theory tools—conceptual and action heuristics—can help evaluators improve programs by expanding conceptions of problems and solutions and by narrowing the focus of decision alternatives for action.
State evaluation in a legislative environment: Adapting evaluation to legislative needs
Authors: Brown Judith R.
Published: January 2005

State legislatures began recognizing evaluation as an important aspect of their oversight responsibilities in the late sixties. Since that time, evaluation has become an integral part of the legislative process. This chapter delineates such key issues as how the Illinois Office of the Auditor General has addressed legislative evaluation and the challenges and dilemmas evaluators must address to enhance their future effectiveness.
Expert opinion in program evaluation
Authors: Nevo David
Published: January 2005

Experts can provide quick and diverse opinions that, properly collected and analyzed, can yield rich evaluation information.
Evaluating community‐level health promotion and disease prevention interventions
Authors: Jackson Christine , Altman David G. , Howard‐Pitney Beth , Farquhar John W.
Published: January 2005

Community health intervention methods, objectives, and contexts are linked to evaluation issues, and some options for addressing these issues are suggested.
Social justice, evaluation, and the educational system
Authors: Ericson David P.
Published: January 2005

The reluctance of the evaluation community to confront issues of social justice in the educational system reflects a misunderstanding of the appropriate nature of value analysis in evaluation and the paramount role of social justice concerns in evaluating social programs and institutions.
At‐risk programs: Evaluation and critical inquiry
Authors: Richardson Virginia
Published: January 2005

Because at‐risk status is socially constructed, school‐level programs designed for at‐risk students and their evaluations should explicitly address the theoretical underpinnings of at‐riskness as enacted within the particular school culture. One way of doing this is through critical inquiry.
Issues in constructing program theory
Authors: Chen Huey‐tsyh
Published: January 2005

In designing theory‐driven evaluations, it is important to understand the normative and causative aspects of program theory, different theory‐construction approaches, the typology of theory‐driven evaluations, and analytical techniques for carrying out the evaluations.
From program theory to tests of program theory
Authors: Mark Melvin M.
Published: January 2005

The benefits of program theory will not fully accrue unless program theory is tested; alternative approaches to such testing are discussed.
Developing and testing program classification and function theories
Authors: Conrad Kendon J. , Buelow Janet R.
Published: January 2005

Methods used and lessons learned in developing and testing theories about the nature and functioning of adult day care are described.
Evaluation within the U.S. Department of Health and Human Services Office of Inspector General
Authors: Mangano Michael F.
Published: January 2005

Rapid, responsive evaluation targeted to decision makers is increasingly becoming more important to improving the quality, efficiency, integrity, and cost of programs at the U.S. Department of Health and Human Services.
Primary inclusion of culturally diverse minority program participants in the evaluation process
Authors: Madison Anna‐Marie
Published: January 2005

Advocates of the participation of multiple stakeholders in evaluation seldom include minority participants in the process, yet ethnic and racial minorities have the most at stake in the evaluation of social services and educational programs.
Charting reform in Chicago schools: Pluralistic policy research
Authors: Sebring Penny A. , Bryk Anthony S.
Published: January 2005

The Consortium on Chicago School Research is a unique research enterprise that is attempting to achieve a productive blend of rigorous social science and vital democratic activities. So far, it has facilitated the development of a research agenda on Chicago school reform and completed surveys of teachers and principals.
Three perspectives on school reform
Authors: Sen Asish , Vaughn Jacqueline B. , Flanagan Thomas
Published: January 2005

School reform has deeply affected the education and business communities in Chicago. In this chapter, three prominent Chicagoans assess reform and its impact.
Should evaluators be certified?
Authors: Love Arnold J.
Published: January 2005

The current status of evaluation as a profession is examined, and two certification approaches for evaluation are described.
Reassessing validity threats in experiments: Focus on construct validity
Authors: Conrad Kendon J. , Conrad Karen M.
Published: January 2005

The focus on internal validity in randomized experiments can be misguided if construct validity is neglected. This chapter provides an overview of construct validity threats in randomized experiments and discusses some implications of reducing these threats for future evaluations.
Keeping research on track
Authors: Fetterman David M.
Published: January 2005

The atmosphere is changing as we examine the real‐world problems associated with the implementation of the experimental design.
From judges to collaborators: Evaluators' roles in science curriculum reform
Authors: O'Sullivan Rita G.
Published: January 2005

Radical changes in the ways science is presented and taught in classrooms are transforming how the science curriculum must be evaluated. These new evaluation strategies, responsive to a program's needs, may require that both internal and external evaluators assume roles more consistent with curriculum developers than curriculum judges.
Plasticity of astroglia: Evidence supporting process elongation by “stretch”
Authors: Jaeger Christine B.
Published: January 2005

The structural plasticity of cerebral astroglia was investigated in vivo by implantation experiments. Immunocytochemical markers for glia filament protein were used to identify the astrocytes. First it was established that implanted nitrocellulose filters provided a substrate for astrocytes from different brain regions of young rats. Astrocytes attached to the filter and projected fine processes into it. Longer implantation times increased the density and length of glial processes within filter spaces. Astrocytes that penetrated the filters implanted in the tectum exhibited more processes than those in the cortex, suggesting regional differences of astrocyte distributions. Second it was observed that astrocyted that attached to the filter formed elongated processes when they were tethered within an expanding matrix. This was shown by implanting the nitrocellulose filter together with PC12 cells that continued to grow. The implantation of neither PC12 cells without filters nor nitrocellulose filters alone induced the formation of elongated astroglia with parallel aligned processes, resembling radial glia. Such glial forms only occurred in the filter/PC12 cell cografts. This indicates that processes of astrocytes adherent to nitrocellulose filters could be stretched in response to expansion of the surrounding tissue.
Cytotopographical specialization of enzymatically isolated rabbit retinal Müller (glial) cells: K+ conductivity of the cell membrane
Authors: Reichenbach Andreas , Eberhardt Wolfgang
Published: January 2005

Müller (radial glial) cells were isolated from rabbit retinae by means of papaine and mechanical dissociation. Regional membrane properties of these cells were studied by intracellular microelectrode recordings of potential responses to local application of high K+ solutions. When different parts of the cell membrane were exposed to high K+, the amplitude of the depolarizing responses varied greatly, indicating a strong regional specialization of the membrane properties. Using morphometrical data of isolated rabbit Müller cells, and a simple circuit model, we calculated the endfoot membrane to constitute more than 80% of the total K+ conductance of the cell; the specific resistivity of the endfoot membrane was about 400 Ωcm2, i.e., more than 40 times less than that of the membrane of the vitread process, which is immediately adjacent. This kind of regional membrane specialization seems to be optimized in respect to the Müller cells+ ability to carry spatial buffering K+ currents.
Schwann cell myelination of the myelin deficient rat spinal cord following X‐irradiation
Authors: Duncan I. D. , Hammang J. P. , Gilmore S. A.
Published: January 2005

The myelin‐deficient (md) rat is an X‐linked myelin mutant that has an abnormality of oligodendrocytes and a severe paucity of myelin throughout the CNS. This lack of myelin makes it an ideal model in which to study the cellular interactions that occur when “foreign” myelinating cells are induced in the milieu of this nonmyelinated CNS. In this study, Schwann cells were induced in the lumbosacral spinal cord by exposing it to radiation, a technique demonstrated repeatedly in other nonmutant strains of rats. Md rats and their age‐matched littermates were irradiated (3,000 to 4,000 R) at 3 days of age and perfused 16–22 days later after pulse labeling with tritiated thymidine. In the md rat, Schwann cell invasion progressed from the area of the spinal cord–nerve root junction and extended into the dorsal columns and adjacent gray matter. Autoradiographic evidence revealed that many of these cells incorporated 3H‐thymidine, indicating that they were undergoing proliferation. Ultrastructural observations showed that there was an integration of these intraspinal Schwann cells with the cells normally occurring in this environment, i.e., oligodendrocytes and astrocytes. The extent of migration and division of Schwann cells, as well as their interactions with glial cells, were similar to those seen in the nonmutant irradiated littermates. These studies provide conclusive evidence that md rat axons are normal with respect to their ability to provide trophic and mitogenic signals to myelinating cells.
Cytoplasmic membrane elaborations in oligodendrocytes during myelination of spinal motoneuron axons
Authors: Waxman S. G. , Sims T. J. , Gilmore S. A.
Published: January 2005

The ultrastructure of paranodal oligodendroglial cytoplasm, which is located in proximity to the forming myelin sheath, was studied during maturation of spinal motoneuron axons in rat. At 8 days postnatal, the paranodal oligodendroglial loops contain a network of membrane‐bound tubulovesicular elements. These membrane elaborations are most common in oligodendroglial loops attached to the outermost layers of the myelin sheath, i.e., paranodal loops closest to the nodal gap. The number of oligodendroglial cytoplasmic profiles per paranodal loop falls over the course of five to ten sequential paranodal loops, and these profiles are nearly absent in paranodal oligodendroglial cytoplasm located distant from the nodal gap. Oligodendrocytes in spinal cords of 14‐ and 20‐day‐old rats and of adult rats did not exhibit networks of tubulovesicular profiles. The appearance of these membrane organelles within oligodendroglial cytoplasm during myelin maturation suggests increased membrane turnover within paranodal cytoplasm located adjacent to the axon that is being myelinated. Membrane turnover within oligodendrocytes may reflect axonal modulation of glial function during myelination.
Prenatal gliogenesis in the developing cerebrum of the mouse
Authors: Choi Ben H.
Published: January 2005

A correlative light microscopic, ultrastructural, and immunocytochemical study was made of the brains of C57BL/6J mice obtained between embryonic day (E‐) 11 to postnatal day (P‐) 3. The deployment of radially oriented glial cells within the neopallium was already apparent by E‐12, at which time the expanded endfeet of processes abutting the basement membrane at the pial surface showed ultrastructural evidence of glial differentiaon. Scattered, horizontally arranged glial cells were also observed within the marginal zone prior to the arrival of the cortical plate neurons. Indirect immunofluorescence for glial fibrillary acidic protein (GFAP) was detected at the outer margins of the neopallium at E‐12, antedating the expression of GFAP in radially organized fibers. Radial fibers traversing the full thickness of the neopallium became strongly immunoreactive for GFAP only at and after day E‐16. These findings provide evidence of early gliogenesis in the developing mouse forebrain and indicate that GFAP is as readily demonstrable in mouse astrocytes and radial glial fibers as it is in those of man and subhuman primates.
Patterns of glial proliferation during formation of olfactory glomeruli in an insect
Authors: Oland Lynne A. , Tolbert Leslie P.
Published: January 2005

Paritioning of the first‐order olfactory neuropil into glomeruli in the developing brain of the moth Manduca sexta occurs only in the presence of olfactory sensory axons and appears to be mediated by changes in glial cells (Oland et al.: J. Neurosci., 8:353–367, 1988). The arrival of sensory axons in the brain triggers changes in glial shape and position that lead to the formation of a glial scaffolding for the developing glomeruli. The presence of mitotic figures in glial cells at stages before glomeruli emerge (Oland and Tolbert: J. Comp. Neurol., 255:196–207, 1987) suggested that glial proliferation might also contribute to the formation of the glomerular envelopes. To determine whether glial proliferation is induced by olfactory axons, we have used 3H‐thymidine to label dividing cells before, during, and after the formation of glomeruli and have compared the patterns of proliferation in normal and chronically unafferented olfactory neuropils. We found significant differences in mitotic indices only after glomerular walls had been established, indicating that the sensory axons induce the formation of glomerular envelopes primarily via the changes in glial morphology and distribution, not by stimulating glial proliferation.
Calcium/Calmodulin‐dependent protein kinase activity in primary astrocyte cultures
Authors: Babcock‐Atkinson E. , Norenberg M.D. , Norenberg L.O.B. , Neary J.T.
Published: January 2005

Calcium, calmodulin‐dependent protein kinase (Ca/CaM kinase) is an important component of calcium signalling mechanisms in the brain, but little is known about the properties of this protein phosphorylation system in astrocytes. Addition of calcium and calmodulin to supernatant or membrane fractions obtained from rat astrocytes in primary culture increased phosphate incorporation into an exogenously added substrate, casein, and into endogenous protein substrates; this increase was greater than that observed with either calcium alone or calmodulin alone. The calcium, calmodulin‐stimulated increase was inhibited by trifluoperazine, and this inhibition could be overcome by the addition of excess calmodulin. The major substrates for Ca/CaM kinase activity were proteins with molecular weights of 59 and 53 kDa, which were similar, but not identical, to the subunits of Ca/CaM kinase type II from brain. The specific activity of Ca/CaM kinase and the phosphorylation of 59 kDa were increased in astrocyte cultures treated and maintained in dibutyryl cyclic adenosine monophosphate (dBcAMP). These results indicate that astrocytes contain Ca/CaM kinase activity and suggest an interaction between the cAMP and calcium/calmodulin messenger systems in these cells.
Evidence for an early role for myelin‐associated glycoprotein in the process of myelination
Authors: Owens Geoffrey C. , Bunge Richard P.
Published: January 2005

The expression of myelin‐associated glycoprotein (MAG) in purified rat Schwann cells following coculture with dorsal root ganglion neurons was compared with the expression of galactocerebroside (GalC) and Po using immunocytochemistry. In defined serum‐free medium, lacking ascorbic acid, in which Schwann cells proliferate but neither ensheathe nor myelinate axons, axonal interaction up‐regulated the cell surface expression of MAG and GalC but not of Po. Excision of neuronal cell bodies resulted in a down‐regulation of both MAG and GalC from the Schwann cell surface. When cocultures were switched to complete medium (serum plus ascorbic acid) to promote myelination, Schwann cells committed to form myelin continued to express high levels of MAG and GalC on their surface, but nonmyelinating Schwann cells down‐regulated MAG and GalC. There was significant MAG immunoreactivity associated with the external aspect of the apparent nodal region of developing myelin sheath. Permeabilization prior to immunostaining revealed that all of the Schwann cell cytoplasmic processes of nascent internodes were significantly stained with anti‐MAG antibodies before the appearance of Po immunoreactivity. The amount of MAG on the surface of mature myelin segments was reduced compared with developing myelin segments, but there was a considerable amount of anti‐MAG staining in the paranodes and Schmidt‐Lanterman incisures. The time of expression and localization of MAG indicates that it may be a critical molecule in the process by which the Schwann cell engulfs an axon destined to be myelinated and establishes the extent of the future internode.
Gliosis in the spinal cords of rats with experimental allergic encephalomyelitis: Immunostaining of carbonic anhydrase and vimentin in reactive astrocytes
Authors: Cammer Wendy , Tansey Francine A. , Brosnan Celia F.
Published: January 2005

Spinal cord sections from rats sensitized to develop experimental allergic encephalomyelitis (EAE) were immunostained with antibodies against glial fibrillary acidic protein (GFAP), carbonic anhydrase, and vimentin, to see whether the latter two antigens could be detected in GFAP‐positive reactive astrocytes. Sixteen days after sensitization (16 dpi) there was intense carbonic anhydrase immunostaining in GFAP‐positive cells in the spinal cords of EAE rats, particularly in the white matter. At 13 and 20 dpi carbonic anhydrase immunostaining in astrocytes was less intense, and in the spinal cord white matter of control animals carbonic anhydrase was not detected in the few GFAP‐positive cells. In the spinal cords of EAE rats vimentin immunostaining was observed in inflammatory cells and astrocytes. In the latter, GFAP and carbonic anhydrase were colocalized with vimentin. The data suggest that carbonic anhydrase expression in astrocytes is an acute response to injury and that vimentin can be detected in astrocytes, as well as inflammatory cells, as early as 16 dpi.
Developmental accumulation and heterogeneity of myelin basic protein transcripts in the chick visual system
Authors: Zopf Dieter , Sonntag Vera , Betz Heinrich , Gundelfinger Eckart D.
Published: January 2005

By selective cloning of gene products newly expressed in the developing chick optic tectum, we have isolated cDNA clones encoding myelin basic protein (MBP). Three different transcripts of the corresponding single copy gene of 2.7 kb, 2.0 kb, and 1.1 kb were observed on Northern blots. In the developing optic lobe, the most abundant RNA (2.7 kb) was detected first at the 14th day in ovo. Nuclease S1 protection experiments revealed further heterogeneity of MBP transcripts, which result from alternative splicing of segments corresponding to the fifth and sixth exon of the homologous murine MBP gene. From these data, at least three different forms of MBP are predicted to exist in the chicken central nervous system.
Dynamic morphological responses of mouse astrocytes in primary cultures following medium changes
Authors: Devon Richard M. , Juurlink Bernhard H.J.
Published: January 2005

Within 5 minutes of changing the medium of 3–4 week old mouse astrocyte cultures, dramatic morphological alterations were seen in the cultures at the phase microscope level. These alterations included the appearance of membrane ruffles, followed by the formation of phase light vacuolar regions. Ultrastructurally, these ruffles could be seen as phagocytic arms, and the vacuoles appeared as blisters of the superficial cell layer. These morphological responses were due to the introduction of new serum proteins. Colloidal gold‐labelled serum proteins were used to visualize the dynamics of the macromolecular uptake following this medium change. Some proteins were taken up by phagocytosis, whereas others were associated with coated vesicles and endosomal vesicles. The majority of these gold‐labelled proteins were concentrated in vacuoles (presumably lysosomes) and were localized in the superficial cellular sheets. Inner cellular sheets contained little colloidal gold‐labelled serum proteins, but displayed prominent pinocytotic profiles. Glucose consumption in these cultures remained constant at 1.6 μmoles/mg protein/hr. Glycogen content varied among individual cells, but it remained constant in the cultures at 60 nmoles bound glucose/mg protein throughout the 48 hour examination period. These results suggest that dense cultures of primary astrocytes may act similarly to the glia limitans.
Chloride enters glial cells and photoreceptors in response to light stimulation in the retina of the honey bee drone
Authors: Coles Jonathan A. , Orkand Richard K. , Yamate Carol L.
Published: January 2005

Double‐barrelled ion‐selective microelectrodes were used to measure free [Cl−] in photoreceptors, extracellular space, and glial cells in superfused slices of drone retina. Tests indicated that with normal superfusate the intracellular electrode signal was due essentially to Cl− and not to some other interfering anion. The results indicate that Cl− is more concentrated in both photoreceptors and glial cells than would be predicted for a passive electrochemical distribution. When the photoreceptors were stimulated by a standard train of 20 ms flashes, 1/s for 90 s, their intracellular free [Cl−] (Cli) rose by 8 ± 1 mM. At the end of stimulation Cli usually continued to rise for up to a further 2 min and then returned toward the baseline over about 10 min. During light stimulation Cli in the glia rose. The magnitude of the increase was 5.1 ± 0.4 mM, about half the increase in Ki. In some extracellular recording sites, light stimulation caused [Cl−] to increase and in others to decrease. The mean change was –0.7 mM, SD 6.5 mM. The Cl− that entered the photoreceptors and the glia was presumably made available by the shrinking of the extracellular space. When the cells were depolarized by increasing [K+] in the superfusate from 7.5 mM to 18 mM, Cli increased. The half‐time of the change in Cli was longer than the half‐time of the depolarization by 10–30 s in the glia and 50–250s in the photoreceptors. During superfusion with 0 Cl− Ringer's solution, the light‐induced rise in extracellular [K+] was greater by a factor of 1.4–2.7, and the clearance after the end of the stimulation was slower. The rate of increase in glial Ki during light stimulation fell; the rate of increase of glial Ki caused by superfusion with raised [K+] (in the absence of Cl−) fell more. We conclude that when extracellular [K+] is increased, entry of Cl− into the glia is necessary for part, but not all, of the net uptake of K+. During light stimulation, the observed movement of Cl− into glia contributes to homeostasis of extracellular [K+], and the cell swelling associated with movement of Cl− into both glia and photoreceptors contributes to homeostasis of extracellular [Na+].
Bradykinin induces inositol 1,4,5‐trisphosphate‐dependent hyperpolarization in K+ M‐current‐deficient hybrid NL308 cells: Comparison with NG108–15 neuroblastoma × glioma hybrid cells
Authors: Higashida H. , Okano Y. , Hoshi N. , Yada Y. , Yokoyama S. , Asaga T. , Fu T. , Nozawa Y.
Published: January 2005

External application of bradykinin (BK) to mouse neuroblastoma × mouse fibroblast hybrid NL308 cells and mouse neuroblastoma × rat glioma hybrid NG108–15 cells produced a transient outward (hyperpolarizing) current. In NG108–15 cells, BK also induced an inward (depolarizing) current associated with a decrease in input membrane conductance, which results from the inhibition of a voltage‐sensitive potassium current, the M‐current. However, in NL308 cells, either no depolarization was elicited by BK or, even if the BK‐induced depolarization was evoked, it was associated with an increased conductance. To explain the above difference, the intracellular second messenger system of NL308 cells was examined in detail. BK induced the rapid accumulation (three‐ to fivefold higher than the control level) of inositol 1,4,5‐trisphosphate (InsP3) in NL308 cells. The cytosolic Ca2+ concentration was also elevated to 540 nM from 180 nM at a basal level. This seems to be enough to activate a voltage‐independent and Ca2+‐sensitive K+ current, resulting in the hyperpolarization. Intracellular injection of InsP3 replicated the hyperpolarization. NL308 cells possess protein kinase C (C‐kinase), with specific activities of C‐kinase in cytosolic and membrane fractions being 233 and 24 pmol/min/mg protein, respectively. The activity associated with particulates became higher after phorbol dibutyrate (PDBu) treatment. But NL308 cells did not show the characteristic inward relaxation by step hyperpolarizations and the outward rectification in the current‐voltage relationship, indicating that the M current is deficient in NL308 cells. Therefore, application of PDBu failed to mimic the inward current. The results suggest the role of InsP3 and C‐kinase in controlling two K+ currents.
Ultrastructural changes in glial cells during regeneration of cockroach peripheral nerve
Authors: Blanco Rosa E.
Published: January 2005

After peripheral nerve 5 in the cockroach Periplaneta americana was cut, changes occurring in the glial cells in the proximal stump were studied immediately after damage and during the process of nerve regeneration. During the first week haemocytes accumulated outside the nerve and morphologically similar granule‐containing cells appeared inside the nerve. These cells were involved in phagocytic activity. Between the second and the fourth week, signs of regeneration were distinguishable; many small axonal sprouts were formed which were surrounded by glial processes, and the nerve stump increased in length. During this period the glial cells produced large amounts of extracellular material in which the bundles of axons and glia were embedded. The structural differences between glial and perineurial cells were lost during these stages of regeneration and there was no restriction to the penetration of the extracellular tracer lanthanum. After 8 weeks, reinnervation of the muscles had taken place, perineurial and glial cells were again distinguishable, and the perineurial cells were able to exclude lanthanum.
Fibroblast growth factor inhibits epidermal growth factor‐induced responses in rat astrocytes
Authors: Huff Kenneth R. , Schreier Wayne
Published: January 2005

The signals which regulate the proliferation of astrocytes have relevance to normal developmental processes, transformational loss of growth control, and reactive gliosis present in many brain disease states. We have studied, in primary cultures of rat astrocytes, a sequential interaction of two growth factors, epidermal growth factor (EGF) and fibroblast growth factor (FGF), which may be relevant to the brain in these conditions. EGF is a strong mitogen and stimulator of 2 deoxyglucose (2 DG) transport with no effect on plating of cells, and FGF is a lesser mitogen and 2 DG uptake stimulator. However, when FGF is given to the cells as a pretreatment, FGF strongly inhibits the ability of EGF to stimulate both DNA synthesis and 2 DG uptake. The inhibition of EGF stimulation by FGF is across the EGF dose‐response curve, present at high and low culture densities, and stable for at least 3 days. Specificity is indicated by lack of inhibition by PDGF pretreatment and much less inhibition of fetal calf serum‐induced stimulations than EGF‐induced stimulation. Cell counts confirmed that the FGF pretreatment also inhibits EGF stimulation of cell division. Because of FGF brain derivation and angiogenic and neurotropic functions, it may serve as a regulator of EGF‐astrocyte interactions in processes such as development, gliomatous transformation, and neural regeneration.
Orthogonal arrays of particles in astroglial cells: Quantitative analysis of their density, size, and correlation with intramembranous particles
Authors: Neuhaus Jochen
Published: January 2005

Astroglial cells were investigated by means of freeze‐fracture in normal rat and mouse brain, cell culture and human gliomas. Membranes of these cells were quantitatively analyzed for their intramembranous particles (IMPs) and orthogonal arrays of particles (OAPs). Measurement of the size of OAPs and IMPs has permitted the search for a correlation between the 7‐nm IMPs, which are distributed randomly in the membrane, and the subunits of OAPs (OAP‐Su, also 7 nm in diameter). Using cultured astroglial cells treated with basic fibroblast growth factor (bFGF), arginine vasopressin, or sorbitol, good evidence for a relationship between the density of 7‐nm IMPs and the size of OAPs can be demonstrated. These findings led to a hypothetical model of OAP modulation. A preliminary report has been published elsewhere (Neuhaus and Wolburg, 1989).
Glial response to axonal injury: In vitro manifestation and implication for regeneration
Authors: Sivron Tomer , Cohen Avi , Duvdevani Revital , Jeserich Gunnar , Schwartz Michal
Published: January 2005

Crushed fish optic axons readily regenerate, while similarly injured rat optic axons do not; the reasons for the differences in regeneration ability may lie in differences in the environment of the axons. We have cultured glial cells from previously crushed optic nerves of fish and rat to determine whether a relationship exists between the ability to regenerate and the nature of the responses of the associated nonneuronal cells to injury. The glial cells were examined using indirect immunofluorescence with antibodies to known glial markers. In the rat cultures, mature GalC oligodendrocytes, which are known to be nonpermissive for axonal growth, were abundant. In contrast, in the fish cultures mature oligodendrocytes were rare, but A2B5positive cells were abundant. The high number of A2B5positive cells in the fish may suggest a high number of immature cells. This interpretation, however, should wait until evidence for glial cell lineage of the fish is available. Additional indication is provided also in the present study that the number of mature oligodendrocytes in the fish is regulated by elements external to the nerve. This study thus demonstrates an important difference between rat and fish optic nerves in the response of glial cells to the optic nerve injury.