bluuebunny/crossref_metadata_2025 huggingface dataset:
Rho GTPase expression in tumourigenesis: Evidence for a significant link
Authors: del Pulgar Teresa Gómez , Benitah Salvador A. , Valerón Pilar F. , Espina Carolina , Lacal Juan Carlos
Published: May 2005

Rho proteins belong to the small GTPases superfamily. They function as molecular switches that, in response to diverse stimuli, control key signaling and structural aspects of the cell. Although early studies proposed a role for Rho GTPases in cellular transformation, this effect was underestimated due to the fact that no genetic mutations affecting Rho‐encoding genes were found in tumors. Recently, it has become evident that Rho GTPases participate in the carcinogenic process by either overexpression of some of the members of the family with oncogenic activity, downmodulation of other members with suggested tumor suppressor activity, or by alteration of upstream modulators or downstream effectors. Thus, alteration of the levels of expression of different members of the family of Rho GTPases has been detected in many types of human tumors leading to a great interest in the cellular effects elicited by these oncoproteins. This essay reviews the current evidence of dysregulation of Rho signaling by overexpression in human tumors. BioEssays 27:602–613, 2005. © 2005 Wiley Periodicals, Inc.
Many roads to resistance: how invertebrates adapt to Bt toxins
Authors: Griffitts Joel S. , Aroian Raffi V.
Published: May 2005

The Cry family of Bacillus thuringiensis insecticidal and nematicidal proteins constitutes a valuable source of environmentally benign compounds for the control of insect pests and disease agents. An understanding of Cry toxin resistance at a molecular level will be critical to the long‐term utility of this technology; it may also shed light on basic mechanisms used by other bacterial toxins that target specific organisms or cell types. Selection and cross‐resistance studies have confirmed that genetic adaptation can elicit varying patterns of Cry toxin resistance, which has been associated with deficient protoxin activation by host proteases, and defective Cry toxin‐binding cell surface molecules, such as cadherins, aminopeptidases and glycolipids. Recent work also suggests Cry toxin resistance may be induced in invertebrates as an active immune response. The use of model invertebrates, such as Caenorhabditis elegans and Drosophila melanogaster, as well as advances in insect genomics, are likely to accelerate efforts to clone Cry toxin resistance genes and come to a detailed and broad understanding of Cry toxin resistance. BioEssays 27:614–624, 2005. © 2005 Wiley Periodicals, Inc.
Is ectopic expression caused by deregulatory mutations or due to gene‐regulation leaks with evolutionary potential?
Authors: Rodríguez‐Trelles Francisco , Tarrío Rosa , Ayala Francisco J.
Published: May 2005

It has long been thought that gene expression is tightly regulated in multicellular eukaryotes, so that expression profiles match functional profiles. This conception emerged from the assumption that gene activity is synonymous with gene function. This paradigm was first challenged by comparative protein electrophoresis studies showing extensive differences in expression patterns among related species. The paradigm is now being challenged by evolutionary transcriptomics using microarray technologies. Most gene expression profiles display features that lack any obvious functional significance. The so‐called “ectopic” expression refers to the expression of genes at times and locations where the target gene is not known to have a function. However, ectopic expression might be associated with genuine function even if this function is not essential or has yet to be ascertained. Alternatively, ectopic expression might come about as a superfluous by‐product of regulatory systems, which would call for a revision of prevailing ideas about the specificity of gene regulation. We herein review available evidence for ectopic expression and the hypotheses proposed for its origin and evolution. We propose that ectopic expression must be regarded as part of an integrated phenotypic whole. It seems likely that ectopic expression represents a leak in the evolution of regulatory systems, but one that is endowed with considerable evolutionary possibilities. BioEssays 27:592–601, 2005. © 2005 Wiley Periodicals, Inc.
Coding repeats and evolutionary “agility”
Authors: Caburet Sandrine , Cocquet Julie , Vaiman Daniel , Veitia Reiner A.
Published: May 2005

The rapid generation of new shapes observed in the living world is the result of genetic variation, especially in “morphological” developmental genes. Many of these genes contain coding tandem repeats. Fondon and Garner have shown that expansions and contractions of these repeats are associated with the great diversity of morphologies observed in the domestic dog, Canis familiaris.1 In particular, they found that the repeat variations in two genes were significantly associated with changes in limb and skull morphology. These results open the possibility that such a mechanism contributes to the diversity of life. BioEssays 27:581–587, 2005. © 2005 Wiley Periodicals, Inc.
Detection of sentinel nodes and micrometastases using radioisotope navigation and immunohistochemistry in patients with gastric cancer
Authors: Uenosono Y , Natsugoe S , Ehi K , Arigami T , Hokita S , Aikou T
Published: May 2005

Background

Patients with early gastric cancer may be treated by minimally invasive surgery. This study investigated the value of sentinel node (SN) navigation surgery, including detection of micrometastases, in patients with clinical (c) T1 and T2 gastric cancer.

Methods

The day before surgery 99mTc-radiolabelled tin colloid was injected submucosally near the tumour. After resecting the stomach, radioisotope uptake in all dissected lymph nodes was measured during and after surgery. Micrometastasis was detected immunohistochemically using an anticytokeratin antibody.

Results

SNs were identified in 99 of 104 patients. The rate of identification of SNs in patients with cT1 and cT2 tumours, excluding three technical failures, was 99 and 95 per cent respectively. Lymph node metastases and/or micrometastases were found in 28 patients (15 cT1 and 13 cT2). In the 15 patients with cT1 tumours, at least one SN contained metastasis and/or micrometastasis. For cT1 tumours, the sensitivity and accuracy of detecting SNs were both 100 per cent. Six patients with cT2 tumours had false-negative results.

Conclusion

SN navigation surgery appears to be clinically useful only for cT1 tumours. Based on SN results, the extent of lymphadenectomy may be reduced in patients with early gastric cancer.
Quality of life assessment in patients with chronic anal fissure after lateral internal sphincterotomy
Authors: Ortiz H , Marzo J , Armendariz P , De Miguel M
Published: May 2005

Background

The aim of this study was to compare quality of life of patients with chronic anal fissure before and after open lateral internal sphincterotomy.

Methods

A prospective study was undertaken of 108 consecutive patients with a history of chronic anal fissure who underwent lateral internal sphincterotomy. Quality of life was measured before and 6 months after operation with the Short-Form 36 (SF-36) Health Survey.

Results

Quality of life improved significantly in six of the eight scales of the SF-36 questionnaire: physical functioning, role physical, bodily pain, energy, social functioning and mental health. There were no significant differences between the 70 patients who had no change in continence after operation and the 38 patients with continence disturbances after sphincterotomy. However, there were significant improvements in four scales in patients without changes in continence compared with improvements in only two scales in those with continence disturbances.

Conclusion

Patients with chronic anal fissure showed an improvement in quality of life 6 months after internal lateral sphincterotomy. Patients with postoperative continence disturbances showed improvement in fewer scales of the SF-36 questionnaire than those without changes in continence.
Prognostic significance of alarm symptoms in patients with gastric cancer
Authors: Stephens M R , Lewis W G , White S , Blackshaw G R J C , Edwards P , Barry J D , Allison M C
Published: May 2005

Background

The aim of this study was to determine the incidence and spectrum of alarm symptoms in patients with newly diagnosed gastric cancer, and to examine the relationship between symptoms and outcome.

Methods

Three hundred consecutive patients with gastric adenocarcinoma were studied prospectively. The outcomes of 40 patients (13·3 per cent) without alarm symptoms (21 men; median age 69 years) were compared with those of the 260 patients (86·7 per cent) with alarm symptoms (175 men; median age 72 years).

Results

It was possible to perform an R0 gastrectomy more often in patients without alarm symptoms (21 patients; 52 per cent) than in those with alarm symptoms (71 patients; 27·3 per cent) (χ2 = 10·35, 1 d.f., P = 0·001). The cumulative survival rate at 5 years was 38 per cent for patients without alarm symptoms versus 15·0 per cent for those with alarm symptoms (χ2 = 10·18, 1 d.f., P = 0·001). In a multivariate analysis, distant metastasis (hazard ratio (HR) 2·73 (95 per cent confidence interval (c.i.) 2·04 to 3·66); P < 0·001), overall stage of cancer (HR 1·83 (95 per cent c.i. 1·53 to 2·19); P < 0·001) and persistent vomiting at diagnosis (HR 1·66 (95 per cent c.i. 1·26 to 2·18); P < 0·001) were independently associated with length of survival.

Conclusion

Alarm symptoms are absent in a significant minority of patients with gastric cancer at diagnosis; these patients stand a better chance of curative surgery and long-term survival than those with alarm symptoms.
Risk of tumour seeding after percutaneous radiofrequency ablation for hepatocellular carcinoma
Authors: Livraghi T , Lazzaroni S , Meloni F , Solbiati L
Published: May 2005

Background

A recent small study reported a high rate of neoplastic seeding after cooled-tip radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) in patients who had undergone previous needle biopsy. Tumour seeding was associated with subcapsular tumour location, poorly differentiated tumours and a high α-fetoprotein (AFP) level. The aim of the present study was to determine the rate of neoplastic seeding after RFA in a large series of unselected patients with HCC who had a long follow-up.

Methods

A total of 1314 patients with 2542 nodules were treated in three centres. Median follow-up was 37 months. Needle biopsy had been performed before RFA in 241 patients (18·3 per cent). The influence of subcapsular location, high AFP level and previous biopsy on risk of tumour seeding was assessed.

Results

Neoplastic seeding was identified in 12 patients (0·9 per cent); the rate was comparable at the three centres (0·9, 0·7 and 1·4 per cent). Only previous biopsy was significantly associated with tumour seeding (P = 0·004).

Conclusion

RFA with a cooled-tip needle was associated with a low risk of neoplastic seeding, even in unselected patients. The use of biopsy before RFA is to be discouraged, particularly when liver transplantation is a possibility at a later date.
Experimental bile duct protection by intraductal cooling during radiofrequency ablation
Authors: Stippel D L , Bangard C , Kasper H U , Fischer J H , Hölscher A H , Gossmann A
Published: May 2005

Background

The use of radiofrequency ablation (RFA) for liver tumours is limited by the proximity of large bile ducts to the targeted lesion. The aim of this randomized study was to evaluate intraductal cooling as a mean of protecting the bile ducts during RFA.

Methods

Twelve pigs underwent RFA adjacent to the right bile duct. After placement of an intraductal cooling catheter and a RFA probe, pigs were randomized to cooling or no cooling. Intraductal temperature was measured in all animals. The bile ducts were assessed by magnetic resonance imaging (MRI) and cholangiography 1 and 28 days after the procedure.

Results

Intraductal cooling abolished the increase of intraductal temperature seen in the absence of cooling. Concurrent cholangiography and MRI showed a biliary lesion in one of six pigs subjected to intraductal cooling and in five of six without cooling (P = 0·040). The biliary injuries were barely visible by MRI on day 1 but were clearly visible on day 28.

Conclusion

Intraductal cooling can prevent biliary injury induced by RFA. The exact parameters for intraductal cooling require further investigation to establish the best compromise between bile duct protection and complete ablation of surrounding tissue.
The effectiveness of parenting support
Authors: Moran Patricia , Ghate Deborah
Published: May 2005

This research review examines what is known about the effectiveness of parenting support, and assesses the international evaluation evidence focusing on primary and secondary prevention programmes. It outlines several factors affecting the success of parenting support interventions in terms of service implementation and delivery, as well as outcomes for children and parents. The conclusions highlight the need for more rigorous UK‐based evaluations, and for further investigation of the support services for specific parenting groups such as very vulnerable families, fathers, and ethnically diverse families. The review also underlines the need for further national policies that address the broader social inequalities affecting the impact of parenting programmes.
Capecitabine plus docetaxel combination therapy
Authors: Verma Shailendra , Maraninchi Dominique , O'Shaughnessy Joyce , Jamieson Carol , Jones Stephen , Martín Miguel , McKendrick Joseph , Miles David , Twelves Chris , Hornberger John
Published: May 2005

BACKGROUND

For patients with anthracycline‐pretreated metastatic breast carcinoma, capecitabine plus docetaxel significantly increased overall survival compared with docetaxel alone. The current study evaluated the cost‐effectiveness of the capecitabine/docetaxel combination versus docetaxel monotherapy, comparing the gain in quality‐adjusted survival with associated health care costs.

METHODS

Patients were randomized to receive 21‐day cycles of oral capecitabine 1250 mg/m2 twice daily, on Days 1–14, plus docetaxel 75 mg/m2 Day 1 (n = 255), or docetaxel 100 mg/m2 on Day 1 (n = 256). Health and cost outcomes in the two arms were compared, and cost‐effectiveness was estimated. Data on survival time and medical care resource use were prospectively collected in the trial. Costs associated with medical care resource use and quality‐of‐life adjustments were obtained from the published literature. The incremental cost‐effectiveness ratio was calculated as the cost per quality‐adjusted life year (QALY) gained.

RESULTS

Capecitabine/docetaxel increased the median overall survival by 3 months compared with docetaxel alone (14.5 vs. 11.5 months). The mean quality‐adjusted survival was increased by 1.8 months in the capecitabine/docetaxel group. The total medical‐resource utilization cost per patient was 8.9% higher with the combination: $24,475 for combination therapy versus $22,477 for single‐agent docetaxel. The mean cost per QALY gained with combination therapy was $13,558 (standard deviation, $6742). Cost savings due to reduced docetaxel dose and hospital use were the major cost offsets with the combination. Sensitivity analyses showed that varying the mean hospital cost per day from the 5th to the 95th percentile resulted in cost‐utility ratios ranging from $20,326 to as low as $6360.

CONCLUSIONS

Capecitabine/docetaxel was a cost‐effective treatment in patients with anthracycline‐pretreated advanced breast carcinoma, and had an incremental cost‐effectiveness ratio that compares very favorably with that of many other oncology therapies. Cancer 2005. © 2005 American Cancer Society.
Lamina‐specific distribution of synaptopodin, an actin‐associated molecule essential for the spine apparatus, in identified principal cell dendrites of the mouse hippocampus
Authors: Bas Orth Carlos , Vlachos Andreas , Del Turco Domenico , Burbach Guido J. , Haas Carola A. , Mundel Peter , Feng Guoping , Frotscher Michael , Deller Thomas
Published: May 2005

Synaptopodin is an actin‐associated molecule found in a subset of telencephalic spines. It is an essential component of the spine apparatus, a Ca2+‐storing organelle and has been implicated in synaptic plasticity (Deller et al. [2003] Proc Natl Acad Sci U S A 100:10494–10499). In the rodent hippocampus, Synaptopodin is distributed in a characteristic region‐ and lamina‐specific manner. To learn more about the cellular basis underlying this distribution, the regional, laminar, and cellular localization of Synaptopodin and its mRNA were analyzed in mouse hippocampus. First, Synaptopodin puncta densities were quantified after immunofluorescent labeling using confocal microscopy. Second, the dendritic distribution of Synaptopodin‐positive puncta was studied using three‐dimensional confocal reconstructions of Synaptopodin‐immunostained and enhanced green fluorescence protein (EGFP)‐labeled principal neurons. Synaptopodin puncta located within dendrites of principal neurons were primarily found in spines (>95%). Analysis of dendritic segments located in different layers revealed lamina‐specific differences in the percentage of Synaptopodin‐positive spines. Densities ranged between 37% (outer molecular layer) and 14% (stratum oriens; CA1). Finally, synaptopodin mRNA expression was studied using in situ hybridization, laser microdissection, and quantitative reverse transcriptase‐polymerase chain reaction. Expression levels were comparable between all regions. These data demonstrate a lamina‐specific distribution of Synaptopodin within dendritic segments of identified neurons. Within dendrites, the majority of Synaptopodin‐positive puncta were located in spines where they represent spine apparatuses. We conclude, that this organelle is distributed in a region‐ and layer‐specific manner in the mouse hippocampus and suggest that differences in the activity of afferent fiber systems could determine its distribution. J. Comp. Neurol. 487:227–239, 2005. © 2005 Wiley‐Liss, Inc.
Morphology and immunohistochemistry of efferent neurons of the goldfish corpus cerebelli
Authors: Ikenaga Takanori , Yoshida Masayuki , Uematsu Kazumasa
Published: May 2005

In teleosts, cerebellar efferent neurons, known as eurydendroid cells, are dispersed within the cerebellar cortex rather than coalescing into deep cerebellar nuclei. To clarify their morphology, eurydendroid cells were labeled retrogradely by biotinylated dextran amine injection into the base of the corpus cerebelli. Labeling allowed the cells to be classified into three types—fusiform, polygonal, and monopolar—depending on their somal shapes and numbers of primary dendrites. The fusiform and polygonal type cells were distributed not only in the Purkinje cell layer but also in the molecular and granule cell layers. The monopolar type cells were distributed predominantly in the Purkinje cell layer of the ventrocaudal portion of the corpus cerebelli. These results suggest that there are some functional differences between these eurydendroid cell types. The eurydendroid cells were double‐labeled by retrograde labeling and immunohistochemistry using specific antibodies against GABA, aspartate, and zebrin II. No GABA‐like immunoreactivity was detected in the retrogradely labeled eurydendroid cells. About half of retrogradely labeled cells were immunoreactive to the anti‐aspartate antibody, suggesting that some eurydendroid cells utilize aspartate as a neurotransmitter. Zebrin II reacts with cerebellar Purkinje cells but left all retrogradely labeled neurons nonreactive, although some of these were surrounded by immunopositive fibers. This relationship between the eurydendroid and Purkinje cells is similar to that between the deep cerebellar nuclei and Purkinje cells in mammals. J. Comp. Neurol. 487:300–311, 2005. © 2005 Wiley‐Liss, Inc.
μ‐opioid receptor mRNA expression in identified hypothalamic neurons
Authors: Zheng Shi‐Xi , Bosch Martha A. , Rønnekleiv Oline K.
Published: May 2005

It has been known for a number of years that μ‐opioid receptor agonists (e.g., morphine, β‐endorphin, and enkephalin) inhibit luteinizing hormone (LH), vasopressin (VP), and oxytocin (OT) release and stimulate prolactin secretion in rodents and primates by an action at the level of the brain. Also, electrophysiological studies have established that hypothalamic neurons, including gonadotropin‐releasing hormone (GnRH), VP, OT, β‐endorphin, and dopamine neurons, are responsive to μ‐receptor activation. Although μ‐receptor expression has been demonstrated in the hypothalamus, there have been few studies localizing these receptors in neurosecretory neurons. Therefore, we sought to document μ‐opioid receptor mRNA expression in immunocytochemically identified hypothalamic neurons. The brains from both female and male guinea pigs were examined by using in situ hybridization and immunocytochemistry. The studies revealed that μ‐receptor mRNA was expressed in different diencephalic regions including the preoptic area, the bed nuclei stria terminalis, the paraventricular nucleus thalamus, and the anterior hypothalamus, as well as the supraoptic (SON), paraventricular (PVH), ventromedial, dorsomedial, and arcuate nuclei of the hypothalamus. Importantly, μ‐opioid receptors were expressed in subpopulations of GnRH neurons (33.25 ± 4.6% and 33.6 ± 3.7% in females and males, respectively), dopamine neurons (51.7 ± 5.8% to 75.0 ± 2.6%, depending on neuronal location), β‐endorphin neurons (68.3.0 ± 4.4%), and VP neurons (41–70%, depending on neuronal location). Because μ‐opioid receptors couple via G‐proteins to activate inwardly rectifying potassium channels and to inhibit calcium channels, the presence of these receptors is likely to play a major role in directly controlling the excitability of hypothalamic neurons. J. Comp. Neurol. 487:332–344, 2005. © 2005 Wiley‐Liss, Inc.
Feedback connections to ferret striate cortex: Direct evidence for visuotopic convergence of feedback inputs
Authors: Cantone Gina , Xiao Jun , McFarlane Nardia , Levitt Jonathan B.
Published: May 2005

Interareal feedback connections are a fundamental aspect of cortical architecture, yet many aspects of their organization and functional relevance remain poorly understood. Previous studies have investigated the topography of feedback projections from extrastriate cortex to macaque area 17. We have extended this analysis to the ferret. We made restricted injections of cholera toxin B (CTb) into ferret area 17 and mapped the distribution of retrogradely labeled cells in extrastriate cortex. In addition to extensive label spreading within area 17, we found dense cell label in areas 18, 19, and 21 and the suprasylvian cortex and sparser connections from the lateral temporal and posterior parietal cortex. We made extensive physiological assessments of magnification factors in the extrastriate visual cortex and used these measures to convert the spread of labeled cortex in millimeters into a span in degrees of visual field. We also directly measured the visuotopic extents of receptive fields in the regions containing labeled cells in cases in which we made both CTb injections and physiological recordings in the same animals; we then compared the aggregate receptive field (ARF) of the labeled region in each extrastriate area with that of the injection site. In areas 18, 19, and 21, receptive fields of cells in regions containing labeled neurons overlapped those at the injection site but spanned a greater distance in visual space than the ARF of the injection site. The broad visuotopic extent of feedback connections is consistent with the suggestion that they contribute to response modulation by stimuli beyond the classical receptive field. J. Comp. Neurol. 487:312–331, 2005. © 2005 Wiley‐Liss, Inc.
Antioxidants and an inhibitor of advanced glycation ameliorate death of retinal microvascular cells in diabetic retinopathy
Authors: Yatoh Shigeru , Mizutani Masakazu , Yokoo Tomotaka , Kozawa Tadahiko , Sone Hirohito , Toyoshima Hideo , Suzuki Seiji , Shimano Hitoshi , Kawakami Yasushi , Okuda Yukichi , Yamada Nobuhiro
Published: May 2005

Background

Pericyte ghosts and acellular capillaries are well known as early histological changes resulting from diabetic retinopathy. These histological changes mean that the cell death of retinal microvessels has accelerated. It was reported that apoptosis of retinal microvascular cells (RMCs) was increased in diabetic patients. Therefore, we investigated apoptosis of RMCs in Goto‐Kakizaki (GK) rats, a type 2 diabetic model, and involvement with antioxidants (a combination of vitamins C and E) or a novel inhibitor of advanced glycation, OPB‐9195.

Methods

GK rats were treated with the antioxidants combination or OPB‐9195 for 36 weeks. We obtained isolated preparations of the vascular network from their retinas by trypsin digestion. Apoptosis of retinal vascular cells was detected with terminal deoxynucleotidyl transferase‐mediated dUTP nick end labeling (TUNEL) assay.

Results

We found that apoptosis of RMCs was increased in the diabetic GK rats. Furthermore, a combination of vitamins C and E and an advanced glycation end‐products inhibitor mostly inhibited this increased apoptosis.

Conclusions

We concluded that apoptosis of RMCs was a good marker that indicates the progression of diabetic retinopathy in GK rats. Both oxidative stress and the accumulation of advanced glycation end‐products appears to promote the apoptosis of retinal microvascular cells, and antioxidants or advanced glycation end‐products inhibitors might ameliorate diabetic retinopathy. Copyright © 2005 John Wiley & Sons, Ltd.
Predicting ordinary kriging errors caused by surface roughness and dissectivity
Authors: Siska Peter P. , Goovaerts Pierre , Hung I‐Kuai , Bryant Vaughn M.
Published: May 2005

The magnitude of kriging errors varies in accordance with the surface properties. The purpose of this paper is to determine the association of ordinary kriging (OK) estimated errors with the local variability of surface roughness, and to analyse the suitability of probabilistic models for predicting the magnitude of OK errors from surface parameters. This task includes determining the terrain parameters in order to explain the variation in the magnitude of OK errors. The results of this research indicate that the higher order regression models, with complex interaction terms, were able to explain 95 per cent of the variation in the OK error magnitude using the least number of predictors. In addition, the results underscore the importance of the role of the local diversity of relief properties in increasing or decreasing the magnitude of interpolation errors. The newly developed dissectivity parameters provide useful information for terrain analysis. Our study also provides constructive guides to understanding the local variation of interpolation errors and their dependence on surface dissectivity. Copyright © 2005 John Wiley & Sons, Ltd.
Novel Caenorhabditis elegans unc‐119 axon outgrowth defects correlate with behavioral phenotypes that are partially rescued by nonneural unc‐119
Authors: Materi Wayne , Pilgrim David
Published: May 2005

UNC‐119 function is necessary for the correct development of the Caenorhabditis elegans nervous system. Worms mutant for unc‐119 exhibit nervous system structural defects, including supernumerary axon branches, defasciculated nerve fibers, and choice point errors. Axons of both mechanosensory (ALM) and chemo‐ sensory (ASI) neurons have elongation defects within the nerve ring. Expressing unc‐119 cDNA in mechanosensory neurons rescues the elongation defect of ALM axons, but expression in ASI neurons does not rescue ASI axon elongation defects. Neither gross movement nor dauer larva formation defects are rescued in either case. However, expressing a construct including introns under the control of the same promoters results in substantial rescue of phenotypic defects. In these cases reporter expression expands to tissues outside those specified by the promoter, notably into head muscles. Surprisingly, expressing an unc‐119 cDNA construct under the control of a muscle‐specific promoter fully rescues the dauer formation defect and substantially rescues movement. Thus, although UNC‐119 normally acts in a cell‐autonomous fashion, the cell‐nonautonomous rescue of neural function suggests that it either acts at the cell surface or that it can be transported into the cell from the extracellular environment and play its normal role. genesis 42:104–116, 2005. © 2005 Wiley‐Liss, Inc.
Robust ascertainment‐adjusted parameter estimation
Authors: Noh Maengseok , Lee Youngjo , Pawitan Yudi
Published: May 2005

Nonrandom ascertainment is commonly used in genetic studies of rare diseases, since this design is often more convenient than the random‐sampling design. When there is an underlying latent heterogeneity, Epstein et al. ([2002] Am. J. Hum. Genet. 70:886–895) showed that it is possible to get unbiased or consistent estimation of population parameters under ascertainment adjustment, but Glidden and Liang ([2002] Genet. Epidemiol. 23:201–208) showed in a simulation study that the resulting estimates are highly sensitive to misspecification of the latent components. To overcome this difficulty, we consider a heavy‐tailed model for latent variables that allows a robust estimation of the parameters. We describe a hierarchical‐likelihood approach that avoids the integration used in the standard marginal likelihood approach. We revisit and extend the previous simulation, and show that the resulting estimator is efficient and robust against misspecification of the distribution of latent variables.Genet. Epidemiol. © 2005 Wiley‐Liss, Inc.
Excitotoxic oligodendrocyte death and axonal damage induced by glutamate transporter inhibition
Authors: Domercq María , Etxebarria Estibaliz , Pérez‐Samartín Alberto , Matute Carlos
Published: May 2005

Glutamate uptake is crucial to terminate glutamate signaling and to prevent excitotoxicity. The present study describes the expression of functional glutamate transporters GLAST and GLT‐1 in oligodendrocytes by means of electrophysiology, uptake assays, and immunocytochemistry. Inhibition of glutamate uptake, both in oligodendrocyte cultures and in isolated optic nerves, increases glutamate levels and causes oligodendrocyte excitotoxicity, which is prevented by alpha‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionic acid (AMPA) and kainate receptor antagonists. Furthermore, glutamate transporter inhibitors or antisense oligonucleotides applied onto the optic nerve in vivo lead to oligodendroglial loss, massive demyelination, and severe axonal damage. Overall, these results demonstrate that the integrity of oligodendrocytes and white matter depends on proper glutamate transporter function. Deregulated transporter activity may contribute to acute and chronic white matter damage. © 2005 Wiley‐Liss, Inc.
Evidence for creatine biosynthesis in Müller glia
Authors: Nakashima Toshihisa , Tomi Masatoshi , Tachikawa Masanori , Watanabe Masahiko , Terasaki Tetsuya , Hosoya Ken‐ichi
Published: May 2005

In high‐energy metabolic tissues like the retina, creatine may play an important role in energy storage and in transmission of phosphate‐bound energy substrates. To prove this, we investigated creatine synthesis in Müller glia. We also characterized the localization of the creatine synthetic enzyme, S‐adenosyl‐L‐methionine:N‐guanidinoacetate methyltransferase (GAMT) in the retina. Reverse transcription‐polymerase chain reaction analysis revealed that L‐arginine:glycine amidinotransferase and GAMT mRNAs were expressed in the retina and the Müller cell line, TR‐MUL5. [14C]Creatine was detected after incubation of isolated rat retina or TR‐MUL5 cells with [14C]glycine, L‐arginine and L‐methionine, suggesting creatine synthesis in Müller glia. Western blot analysis also revealed expression of GAMT protein in the rat retina and TR‐MUL5 cells. Furthermore, confocal immunofluorescent microscopy of dual‐labeled rat retinal sections demonstrated co‐localization of GAMT with glutamine synthetase. Taken together, the results of the present study indicate creatine synthesis in Müller glia, implying an important role of creatine in energy metabolism in the retina. © 2005 Wiley‐Liss, Inc.
Tenascin C induces a quiescent phenotype in cultured adult human astrocytes
Authors: Holley Janet E. , Gveric Djordje , Whatmore Jacqueline L. , Gutowski Nicholas J.
Published: May 2005

Astrocytic scar formation occurs subsequent to brain and spinal cord injury and impedes repair. The exact mechanisms of scar formation have yet to be elucidated but it is known that astrocytes within the scar have a different antigenic phenotype from normal or reactive astrocytes. Astrocyte cell culture offers a suitable system to identify factors that induce the scar phenotype as well as factors that reverse this process and that may help identify therapeutic strategies to treat astrogliosis. However, when placed in standard culture conditions, astrocytes become activated/reactive and express molecules characteristic of scar tissue in vivo. In the present study, we made use of this phenomenon to identify culture conditions that change the activated phenotype of cultured astrocytes into one characteristic of normal quiescent astrocytes. In particular, we examined the effect of extracellular matrix (ECM) proteins found in the human brain, on the phenotype of human adult astrocytes. Significantly fewer astrocytes expressed scar properties when grown on tenascin‐C (TN‐C) than those cultured on other ECM proteins or poly‐L‐lysine‐coated dishes. TN‐C also significantly reduced the proliferation rate of the astrocytes in vitro. In addition, further manipulation of culture conditions induced partial astrocyte reactivation. Our findings suggest that astrocytes grown on TN‐C revert to a quiescent, nonactivated state that is partially reversible. This raises the possibility that therapeutic strategies aimed at manipulating TN‐C levels during CNS injury may help reduce astrocytic scarring. © 2005 Wiley‐Liss, Inc.
Functions and distribution of voltage‐gated sodium and potassium channels in mammalian schwann cells
Authors: Chiu S. Y.
Published: May 2005

Recent patch‐clamp studies on freshly isolated mammalian Schwann cells suggest that voltage‐gated sodium and potassium channels, first demonstrated in cells under culture conditions, are present in vivo. The expression of these channels, at least at the cell body region, appears to be dependent on the myelinogenic and proliferative states of the Schwann cell. Specifically, myelin elaboration is accompanied by a down regulation of functional potassium channel density at the cell body. One possibility to account for this is a progressive regionalization of ion channels on a Schwann cell during myelin formation. In adult myelinating Schwann cells, voltage‐gated potassium channels appear to be localized at the paranodal region. Theoretical calculations have been made of activity‐dependent potassium accumulations in various compartments of a mature myelinated nerve fibre; the largest potassium accumulation occurs not at the nodal gap but rather at the adjacent 2–4 μm length of periaxonal space at the paranodal junction. Schwann cell potassium channels at the paranode may contribute to ionic regulation during nerve activities.
Neurons and astrocytes influence the development of purified o‐2a progenitor cells
Authors: Dutly F. , Schwab M. E.
Published: May 2005

To investigate the possible role of neurons and astrocytes for oligodendrocyte development we prepared a pure population of precursor cells positive for the precursor marker GD3 with the help of fluorescence‐activated cell sorting (FACS). Large numbers of highly purified cells were obtained from postnatal day 1 rat brainstems and cultured in different media and sera, and in conditioned media.

As described in the literature for optic nerve O‐2A progenitors, GD3‐sorted brainstem cells cultured in medium containing 10% fetal calf serum (FCS) acquired a star‐shaped morphology and differentiated into GD3‐ and GFAP‐positive type‐2 astrocytes. On the other hand, in serum‐free medium, most of the cells differentiated into oligodendrocytes (O1‐/galactocerebroside‐positive).

Sensory neuron conditioned media promoted survival and proliferation of the precursor cells. The spontaneous differentiation of progenitor cells into oligodendrocytes was retarded by the mitogen. Antibodies against platelet‐derived growth factor (PDGF) completely blocked the mitotic effect and allowed spontaneous oligodendrocyte differentiation to occur.

Cultured astrocytes also secreted PDGF as a mitogen. However, postnatal astrocytes also released a potent signal promoting oligodendrocyte differentiation. The type of factor(s) released depended on the age of the astrocytes, since only conditioned medium of postnatal but not of embryonic astrocytes promoted oligodendrocyte differentiation, suggesting that astrocyte maturation directly influences oligodendrocyte differentiation. Different concentrations of PDGF could not reproduce this differentiation‐inducing effect.

This study suggests that interactions between O‐2A progenitor cells, neurons, and astrocytes could be required to regulate and complete the oligodendrocyte developmental pathway. Astrocytes, themselves possibly under neuronal influences, might regulate first the proliferation of the precursor cells, and, later in development, the differentiation into mature oligodendrocytes or type‐2 astrocytes.
Phorbol‐12‐myristate‐13‐acetate (PMA) and inhibitors of protein kinase C alter glial fibrillary acidic protein (GFAP) mRNA levels
Authors: Sharma Nishi , Norman‐O'guin Kathleen , Shafit‐Zagardo Bridget
Published: May 2005

Glial fibrillary acidic protein (GFAP) mRNA levels in the human astrocytoma line U‐373MG were examined to explore further the effects of agents that regulate protein kinase C. U‐373MG cells exhibit a biphasic change in steady‐state GFAP mRNA in the presence of the phorbol ester phorbol‐12‐myristate‐13‐acetate (PMA). Short‐term treatment with PMA results in increased GFAP mRNA, and long‐term treatment results in decreased GFAP mRNA. Nuclear run‐off experiments demonstrate that the PMA‐induced decrease in GFAP mRNA levels is not at the level of GFAP gene transcription. PMA exerts its effect in the presence of protein synthesis inhibitors, demonstrating that de novo protein synthesis is not required for the PMA‐induced changes in GFAP mRNA. Staurosporine, a protein kinase C inhibitor, reduces GFAP mRNA expression in a dose‐dependent manner; in the presence of PMA the effect is additive. By contrast HA1004, an inhibitor of cAMP‐dependent protein kinase, is not inhibitory to GFAP steady‐state mRNA. Total protein kinase C activity was determined to be 2,398.8 ± 94.3 pmol/min/mg protein, with most of the activity in the cytosol. Short‐term PMA treatment results in the translocation of the cytosolic protein kinase C activity to the membrane. Long‐term PMA treatment results in a decrease in total protein kinase C activity indicating that downregulation occurs. These studies demonstrate that in the U‐373MG cells, protein kinase C inhibitors and long treatment with PMA result in a decrease in steady‐state GFAP mRNA.
Rumpshaker: An X‐linked mutation causing hypomyelination: Developmental differences in myelination and glial cells between the optic nerve and spinal cord
Authors: Fanarraga M. L. , Griffiths I. R. , McCulloch M. C. , Barrie J. A. , Kennedy P. G. E. , Brophy P. J.
Published: May 2005

The X‐linked mutation rumpshaker (rsh), which is probably an allele of jimpy (jp), causes hypomyelination in the CNS of mice. This study examines the developmental expression of the morphology, glial cells, and immunostaining of myelin proteins in the optic nerve and spinal cord. The optic nerve contains varying numbers of amyelinated and myelinated fibres. The majority of such sheaths are of normal thickness whereas in the spinal cord most axons are associated with a disproportionately thin sheath which changes little in thickness during development. In the optic nerve glial cell numbers are elevated in mutants during early and peak myelination but then fall slightly below normal in adults. In contrast, the number of glial cells is consistently elevated after 16 days of age in the spinal cord. The majority of the alterations to total glial cells are due to corresponding changes in the oligodendrocyte population. Immunostaining intensity is somewhat reduced for myelin basic protein (MBP) and the C‐terminal common to proteolipid protein (PLP) and DM‐20 and profoundly decreased for the PLP‐specific peptide. Glial fibrillary acidic protein (GFAP) is increased in rsh. It is probable that some of the variation in myelination between optic nerve and cord in rsh is related to the difference in axon diameter in the two locations, as there are adequate numbers of oligodendrocytes at the time of myelination. However, the effect of the mutation on cell development in the brain and the spinal cord may be different. The immunostaining indicates a marked deficiency in PLP in myelin but suggests that DM‐20 levels may be relatively normal. rsh shows several major differences from jp and other X‐linked myelin mutants, particularly in relation to oligodendrocyte numbers, and will be useful to elucidate the role of the PLP gene in influencing oligodendrocyte differentiation and survival.
Developmental appearance, antigenic profile, and proliferation of glial cells of the human embryonic spinal cord: An immunocytochemical study using dissociated cultured cells
Authors: Aloisi Francesca , Giampaolo Adele , Russo Giovanni , Peschle Cesare , Levi Giulio
Published: May 2005

We have investigated the time of appearance of the earliest differentiating glial cell types of human spinal cord using a panel of antigenic markers to identify them in cultures from 6‐ to 9‐week‐old human embryos. Immunolabeling performed at 14 h in vitro with the O4 mAb, an early oligodendrocyte marker, showed the presence of oligodendrocytes during the 7th week of age. At 8 weeks only a few of the O4+ cells expressed galactocerebroside (GalC), a marker of more differentiated oligodendrocytes. All the O4+ and GalC+ cells were vimentin+ and some of the GalC+ cells were A2B5+, GD3+ and SSEA‐1+. During the first week in vitro many of the O4+ cells exhibiting a more immature, bi‐ or tri‐polar morphology incorporated [3H]thymidine into their nuclei. Cells expressing the astrocyte‐specific marker GFAP could be first observed at 8 weeks; almost all of these GFAP+ cells, which should correspond to radial glia on the basis of the current literature, were vimentin+, A2B5+, GD3+, and SSEA‐1+. At 2 days in vitro incorporation of [3H]thymidine could be shown in a small fraction of these cells. The finding that radial glia and oligodendrocytes expressed similar antigenic features and the additional observation that a small, but consistent fraction of the cells were simultaneously labeled by O4 and anti‐GFAP antibodies support the hypothesis that, in the human spinal cord, radial glial cells can give rise to both oligodendrocytes and astrocytes; in this respect, radial glial cells may be similar to the A2B5+, GD3+, vimentin+ bipotential glial progenitors previously identified in cultures from developing rat CNS, which also express A2B5, GD3, and vimentin.
Mechanisms of pH recovery from intracellular acid loads in the leech connective glial cell
Authors: Szatkowski Marek , Schlue Wolf‐Rüdiger
Published: May 2005

We used double‐barrelled, neutral carrier, pH‐sensitive microelectrodes to study the mechanisms by which the intracellular pH (pHi) is regulated in the connective glial cells if the medicinal leech. In HEPES‐buffered, nominally CO2/HCO3−‐free solutions the recovery of pHi from intracellular acidosis is Na+‐dependent and reduced by at least half in the presence of amiloride, suggesting the action of Na+:H+ exchange. The rate of pHi recovery by this mechanism can be increased by raising the extracellular buffering power or by increasing extracellular pH. The presence of CO2/HCO3− greatly increases the rate of pHi rocovery from intracellular acidosis. This CO2/HCO3−‐stimulated recovery is also dependent on external Na+, largely Cl−‐independent, inhibited by DIDS, and accompanied by membrane hyperpolarization. This is consistent with it being mediated by the electrogenic cotransport of Na+ and HCO3− into the cells. A Cl−‐dependen component to Na+‐ and HCO3−‐dependent regulation is most easily explained by the added presence of a Na+‐dependent exchange of HCO3− and Cl−.
Regulation of receptor‐mediated shape change in astroglial cells
Authors: Shain W. , Bausback D. , Fiero A. , Madelian V. , Turner J. N.
Published: May 2005

Activation of adenylate cyclase in astroglial cells in culture results in a rapid change in cell shape that appears to occur by the active movement of cytoplasm from peripheral cell regions to the perinuclear space with processes being formed along regions that remain extended. Three series of experiments were designed to determine how shape change occurred. First, the Ca2+‐dependency of shape change was determined by reducing intracellular Ca2+ concentrations to ≤50 nM or increasing intracellular Ca2+ concentrations to ≥1 μM. Neither of these changes significantly affected the rate of receptor‐mediated shape change. Second the role that longer‐lived, acetylated microtubules play in receptor‐mediated shape change was assessed by visualizing microtubules using a polyclonal antibody to brain 6S tubulin or a monoclonal antibody to oligomers of tubulin to monitor total tubulin distribution and a monoclonal antibody to acetylated tubulin to describe the distribution of these microtubules. Three‐dimensional distribution of microtubules was observed by optical sectioning of cultures using a laser scanning confocal imaging system. The distribution of acetylated tubules in control cells was similar to that observed with the antibodies to tubulin. Following treatment with 100 nM isoproterenol to stimulate shape change, there was a dramatic redistribution of microtubules; however, the distribution of acetylated tubules was again similar to the total microtubules. Analysis of the optical sections recorded using the confocal attachment revealed that while control cells were relatively flat (cell height = 4 μm), the perinuclear region of isoproterenol‐treated cells extended much higher above the substrate (cell height = 13 μm). Third, the role of microtubule assembly and disassembly were assessed using colchicine and taxol. Results from these experiments suggest that microtubule reassembly is necessary for receptor‐mediated shape change. Control experiments indicated that colchicine or taxol treatment did not inhibit either cAMP synthesis or another cAMP‐dependent process, receptor‐mediated taurine release. Together these results indicate that receptor‐mediated shape change in astroglial cells occurs by a Ca2+‐independent mechanism that results in active movement of cytoplasm to the perinuclear region. This process is dependent on microtubule reassembly suggesting that shape change may occur by active movement of material along microtubules or by microtubule redistribution.