bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphological plasticity of olfactory ensheathing cells is regulated by cAMP and endothelin‐1
Authors: Vincent Adele J. , West Adrian K. , Chuah Meng Inn
Published: January 2003

Olfactory ensheathing cells (ECs) are a promising tool for the repair of injury in the adult central nervous system. However, important aspects of the cell biology of ECs remain unclear, such as whether ECs exist as a single population or as two subpopulations with Schwann cell‐like and astrocyte‐like characteristics. The morphologies of these subpopulations are used as defining characteristics, yet ECs are known to be morphologically plastic. To elucidate this apparent inconsistency, we investigated the morphological plasticity of ECs in culture. We defined purified ECs as immunopositive for both p75 neurotrophin receptor and glial fibrillary acidic protein. In MEM D‐valine modification + 10% dialyzed fetal calf serum, 87%–90% of ECs displayed a flat morphology. In three different serum‐free media (N2 medium, neurobasal medium + B27 supplement, and DMEM/F‐12 medium + G5 supplement), 78%–84% of ECs displayed process‐bearing morphology. Ensheathing cells switched reversibly between these morphologies within a day of the serum conditions being changed. Exposure to 1 nM endothelin‐1 in serum‐free medium prevented the switch from flat to process‐bearing morphology, while 1 mM dibutyryl cAMP accelerated this change. The effects of both agents were completely reversible and similar to that reported for astrocytes. Both flat and process‐bearing ECs were immunopositive for brain‐derived neurotrophic factor, nerve growth factor, neurotrophin‐4, and TrkB but not TrkA. Together, these results suggest that ECs exist as a single morphologically plastic population. GLIA 41:393–403, 2003. © 2003 Wiley‐Liss, Inc.
Quinolinic acid upregulates chemokine production and chemokine receptor expression in astrocytes
Authors: Guillemin Gilles J. , Croitoru‐Lamoury Juliana , Dormont Dominique , Armati Patricia J. , Brew Bruce J.
Published: January 2003

Within the brain, quinolinic acid (QUIN) is an important neurotoxin, especially in AIDS dementia complex (ADC). Its production by monocytic lineage cells is increased in the context of inflammation. However, it is not known whether QUIN promotes inflammation. Astrocytes are important in immunoregulation within the brain and so we chose to examine the effects of QUIN on the astrocyte. Using purified primary human fetal astrocyte cultures, we determined chemokine production using ELISA assays and RT‐PCR and chemokine receptor expression using immunocytochemistry and RT‐PCR with QUIN in comparison to TNFα, IL‐1β, and IFNγ. We found that QUIN induces astrocytes to produce large quantities of MCP‐1 (CCL2) and lesser amounts of RANTES (CCL5) and IL‐8 (CXCL8). QUIN also increases SDF‐1α (CXCL12), HuMIG (CXCL9), and fractalkine (CX3CL1) mRNA expression. Moreover, QUIN leads to upregulation of the chemokine receptor expression of CXCR4, CCR5, and CCR3 in human fetal astrocytes. Most of these effects were comparable to those induced by TNFα, IL‐1β, and IFNγ. The present work represents the first evidence that QUIN induces chemokine and chemokine receptor expression in astrocytes and is at least as potent as classical mediators such as inflammatory cytokines. These results suggest that QUIN may be critical in the amplification of brain inflammation, particularly in ADC. GLIA 41:371–381, 2003. © 2003 Wiley‐Liss, Inc.
Expression of chemokines and their receptors in human and simian astrocytes: Evidence for a central role of TNFα and IFNγ in CXCR4 and CCR5 modulation
Authors: Croitoru‐Lamoury Juliana , Guillemin Gilles J. , Boussin François D. , Mognetti Barbara , Gigout Laure I. , Chéret Arnaud , Vaslin Bruno , Le Grand Roger , Brew Bruce J. , Dormont Dominique
Published: January 2003

Chemokines are key mediators of the selective migration of leukocytes that occurs in neurodegenerative diseases and related inflammatory processes. Astrocytes, the most abundant cell type in the CNS, have an active role in brain inflammation. To ascertain the role of astrocytes during neuropathological processes, we have investigated in two models of primary cells (human fetal and simian adult astrocytes) the repertoire of chemokines and their receptors expressed in response to inflammatory stimuli. We demonstrated that, in the absence of any stimulation, human fetal and simian adult astrocytes express mRNA for receptors APJ, BOB/GPR15, Bonzo/CXCR6, CCR2, CCR3, CCR5, CCR8, ChemR23, CXCR3/GPR9, CXCR4, GPR1, and V28/CX3CR1. Moreover, TNFα and IL‐1β significantly increase BOB/GPR15, CCR2, and V28/CX3CR1 mRNA levels in both models. Furthermore, TNFα and IFNγ act synergistically to induce expression of the major coreceptors for HIV infection, CXCR4 and CCR5, at both the mRNA and protein levels in human and simian astrocytes, whereas CCR3 expression was not affected by cytokine treatment. Finally, TNFα/IFNγ was the most significant cytokine combination in leading to a pronounced upregulation in a comparable, time‐dependent manner of the production of chemokines IP‐10/CXCL10, RANTES/CCL5, MIG/CXCL9, MCP‐1/CCL2, and IL‐8/CXCL8. In summary, these data suggest that astrocytes serve as an important source of chemokines under the dependence of a complex cytokine regulation, and TNFα and IFNγ are important modulators of chemokines and chemokine receptor expression in human as well as simian astrocytes. Finally, with the conditions we used, there was no difference between species or age of tissue. GLIA 41:354–370, 2003. © 2003 Wiley‐Liss, Inc.
Astrocytes in culture express fibrillar collagen
Authors: Heck Nicolas , Garwood Jeremy , Schütte Katrin , Fawcett James , Faissner Andreas
Published: January 2003

The use of monoclonal antibodies has led to much progress in the characterization of extracellular matrix components of the CNS. F1C3 is a monoclonal antibody raised against the astrocytic cell line, Neu7. Analysis by immunoprecipitation and Western blots of the F1C3 antigen in Neu7 cell lysates and conditioned medium reveals a recognition of several protein bands around 140–230 kD. Internal peptide sequence data from these bands indicate that they are highly homologous to fibrillar collagens, and the F1C3 antigen is specifically digested by the collagenase I protease. Other glial cell lines show F1C3 antigen expression including A7, C6, and U373. Cultures of neonatal primary astrocytes also express F1C3 antigen, and Western blot analysis of rat brain extracts from different ages and parts of the brain confirm an in vivo expression of F1C3 protein. The significance of the expression of fibrillar collagen‐like proteins by astrocytes is discussed together with its possible implication during developmental processes and in the context of CNS lesions and regeneration. GLIA 41:382–392, 2003. © 2003 Wiley‐Liss, Inc.
Surface carbonic anhydrase activity on astrocytes and neurons facilitates lactate transport
Authors: Svichar Nataliya , Chesler Mitchell
Published: January 2003

A number of studies have provided physiological evidence for extracellular carbonic anhydrase (CA) in brain. Association of extracellular CA with glia has been limited to functional studies of gliotic slices and retinal Muller cells. While astrocytes contain intracellular CA, there has been no direct evidence for surface CA on these cells. In fact, some morphological studies suggest that the extracellular CA in brain parenchyma resides on neurons, not glia. There has been no functional demonstration of extracellular CA activity on CNS neurons, however. Here we capitalized on the H+ dependence of inward lactate transport to reveal functional extracellular CA activity on cultured astrocytes and acutely isolated hippocampal pyramidal neurons. Exposure to 20 mM L‐lactate produced a rapid acidification of astrocytes that was reversibly blocked by 10 μM benzolamide. The lactate‐induced acidification (LIA) was also blocked by a dextran‐conjugated CA inhibitor. In CO2/HCO3−‐free, HEPES‐buffered media, the LIA was largely unaffected. Acutely dissociated hippocampal pyramidal neurons underwent a similar LIA that was reversibly blocked by benzolamide. Surface CA is likely to facilitate lactate transport by enabling rapid replenishment (i.e., buffering) of surface H+ required for inward lactate‐H+ cotransport. These results demonstrate functional surface CA for the first time on individual mammalian astrocytes and neurons and suggest that this enzyme may play a role in the utilization of monocarboxylate substrates such as lactate and pyruvate by the brain. GLIA 41:415–419, 2003. © 2003 Wiley‐Liss, Inc.
Postnatal development of GFAP in mouse visual cortex is not affected by light deprivation
Authors: Corvetti Luigi , Capsoni Simona , Cattaneo Antonino , Domenici Luciano
Published: January 2003

Mammalian visual cortex is immature at birth and develops gradually during defined postnatal temporal windows. In the present work, we studied the maturation of astrocytes in developing mouse visual cortex (VC). The cellular distribution and the level of glial fibrillary acidic protein (GFAP) were analyzed by immunohistochemistry and Western blotting. Experiments were performed at different postnatal ages: postnatal day 12 (P12), before eye opening; P24, corresponding roughly to the peak of the critical period for monocular deprivation, and P60, after the end of the critical period. At P12, GFAP immunoreactivity (IR) was distributed throughout all cortical layers. At P24, there was a prominent localization of GFAP IR in layers I, II, and VI, while cortical layers III, IV, and V contained no longer GFAP IR cells. No differences were found in GFAP IR between P24 and P60. Western blot analysis revealed a reduction of GFAP expression in the VC at P24 with respect to P12 and no significant difference between P60 and P24. These results show that GFAP expression is modulated during early postnatal development. To know whether visual experience influences the maturation pattern of GFAP expression, mice were dark‐reared from P12 to P24. Dark rearing did not change the distribution and the expression of GFAP. Our results indicate that maturation of GFAP expression occurs early in postnatal development in mouse VC. In addition, we showed that GFAP development is not affected by visual deprivation. GLIA 41:404–414, 2003. © 2003 Wiley‐Liss, Inc.
Human polyomavirus DNA is not detected in Guthrie cards (dried blood spots) from children who developed acute lymphoblastic leukemia
Authors: Priftakis Peter , Dalianis Tina , Carstensen John , Samuelsson Ulf , Lewensohn‐Fuchs Ilona , Bogdanovic Gordana , Winiarski Jacek , Gustafsson Britt
Published: January 2003

Background

Epidemiological evidence has suggested that some childhood acute lymphoblastic leukemia (ALL) may be initiated in utero and may have an infectious etiology. The human polyomavirus JC virus (JCV) has been discussed as a candidate virus, but its presence has not been demonstrated in leukemia cells from children with ALL. The aim of this study was, therefore, to investigate if prenatal human polyomavirus infection could still indirectly be correlated to the development of childhood ALL.

Procedure

Fifty‐four Guthrie cards (stored, dried blood spots filter papers, routinely collected from newborns for different screening analyses), collected at 3–5 days of age, from Swedish children who subsequently developed ALL, as well as from 37 healthy controls, were investigated by nested PCR for the presence of human polyomaviruses JCV and BK virus (BKV).

Results

JCV and BKV DNA were not detected in any of the Guthrie cards from ALL patients or from healthy controls, although all tested samples had amplifiable DNA as confirmed by an HLA DQ PCR.

Conclusions

JCV or BKV were not found in any of the dried blood spots of children who later developed ALL or in the healthy controls. These findings suggest that it is unlikely that childhood ALL is associated with an in utero infection with JCV or BKV, although it is not possible to exclude an association with an in utero infection that has become latent in the kidneys with very low levels of circulating virus at birth. Med Pediatr Oncol 2003;40:219–223. © 2003 Wiley‐Liss, Inc.
Clinical outcome in children with craniopharyngioma treated with primary surgery and radiotherapy deferred until relapse
Authors: Kalapurakal John A. , Goldman Stewart , Hsieh Y.C. , Tomita Tadanori , Marymont Maryanne H.
Published: January 2003

Background

To report the clinical outcome in children with craniopharyngioma following primary surgery and deferred radiotherapy at relapse.

Procedure

Twenty‐five children with craniopharyngioma were treated with primary surgery. Total resection was achieved in 19 children (76%), while in 24% total resection was not achieved due to tumor adhesion to adjacent critical structures. None of these children received radiation therapy immediately after total or sub‐total resection. Radiotherapy was delivered at the time of relapse in 11 patients (44%).

Results

The median follow‐up from primary surgery was 10 years (3–16 years). The 14 year overall survival was 100%. Tumor recurrence was observed in (12/25) 48% at a median interval of 17 months. Tumor recurrence following total resection was 6/19 (32%) compared to 100% (6/6) following sub‐total resection, and radiotherapy. The 2, 3, and 6 years relapse‐free survival following initial surgery was 72, 55, and 50%, respectively. Univariate analysis revealed only extent of surgery to be significant for local recurrence (P < 0.0001). The sequelae observed in these patients included panhypopituitarism (100%), appetite disorders and hypothalamic obesity (32%), neuropsychological and behavioral disorders (20%), and sleep disorders (12%). Majority of children with non‐endocrine complications had a local recurrence requiring further surgery and radiotherapy.

Conclusions

The two standard treatment options in children with craniopharyngioma are primary surgery and sub‐total resection followed by radiotherapy. In certain subgroups of patients such as those with large tumors and hypothalamic extension, primary surgery is associated with a high incidence of complications and high failure rates. We recommend utilization of an individualized risk‐based treatment approach, that attempts to maximize cure rates without compromising long‐term functional outcome in children with craniopharyngiomas. Med Pediatr Oncol 2003;40:214–218. © 2003 Wiley‐Liss, Inc.
Effects of retinoic acid on proliferation, apoptosis, cytotoxicity, migration, and invasion of neuroblastoma cells
Authors: Voigt A. , Zintl F.
Published: January 2003

Background

Because of the known property of less aggressiveness of differentiated cells compared to immatured cells all attempts are made to elucidate whether differentiation inducers possibly could be applied for neuroblastoma therapy. We are interested in examining the influence of retinoic acid (RA) on proliferation, apoptosis, cytotoxicity, migration, and invasion in dependence of the differentiation of neuroblastoma cells classified into N‐type (SK‐N‐FI, SH‐SY5Y), I‐type (SK‐PN‐DW), and S‐type (SK‐N‐LO, SK‐N‐MC) cells.

Procedure

Neuroblastoma cells were exposed to 10−5 M RA and 200 ng/ml camptothecin (CAM) (control substance for apoptosis). Proliferation, apoptosis, and cytotoxicity were quantified by photometric assays. The influence on migration and invasion of neuroblastoma cells was examined by a scratch‐test and by the measurement of the invasion through matrigel coated chamber inserts.

Results

In general, RA treatment induced proliferation inhibition predominantly in the cell lines SK‐PN‐DW (16%, P < 0.05) and SK‐N‐MC (8%, (P < 0.001), respectively. In the N‐type cell lines SK‐N‐FI (P > 0.05) and SH‐SY5Y (P < 0.001) no proliferation inhibition was determined conforming with no detection of apoptosis. CAM confirmed its capability to induce apoptosis in the cell lines SH‐SY5Y (43.6%, P < 0.05), SK‐PN‐DW (54.8%, P > 0.05), and SK‐N‐MC (28.9%, P < 0.0 01) except for SK‐N‐FI with only 9.3% (P > 0.05), but after 24 hr of treatment. Minor signs of restricted migration were observed, while RA treatment reduced significantly the invasion rate through Matrigel of SK‐N‐FI to 13.3% (P < 0.01), SH‐SY5Y to 19.2% (P < 0.05), SK‐N‐MC to 27.8% (P < 0.05), and SK‐N‐LO to 17.7% (P < 0.01).

Conclusions

It is demonstrated that RA treatment can interfere with cell growth and in invasion by inducing neuronal differentiation in N‐type and apoptosis in S‐type neuroblastoma cell lines. Med Pediatr Oncol 2003;40:205–213. © 2003 Wiley‐Liss, Inc.
Characteristics and adequacy of intravenous morphine infusions in children in a paediatric oncology setting
Authors: Flogegård Helena , Ljungman Gustaf
Published: January 2003

Background

Pain management is central in the care of patients in paediatric oncology. Intravenous (i.v.) morphine infusion is an important treatment modality. The objectives of this study were to identify the characteristics of children who receive i.v. morphine infusions in a paediatric oncology setting and to describe the effectiveness, tolerability, and limiting side‐effects of this treatment.

Procedure

We prospectively collected evaluation charts for all morphine infusions in a paediatric oncology unit during a 4‐year period, and reviewed the medical records of the patients. The incidence of breakthrough pain was used as a measure of the effectiveness of morphine treatment. For comparison, patients were grouped according to causes of pain; minor surgery, major surgery, tumour/disease, or treatment side‐effects.

Results

Overall, 72 individuals (36% of all 201 patients diagnosed in the unit) were given morphine infusions. Patients with pain after major surgery suffered from more breakthrough pain than the other patients during the 1st day of morphine treatment even though their morphine consumption was almost twice as high (0.64 vs. 0.36 mg/kg, P < 0.001); 92% of these patients had solid tumours. Common morphine side‐effects were vomiting (38%), nausea (32%), and constipation (24%).

Conclusions

Patients who undergo major tumour surgery require extensive pain management to achieve acceptable post‐operative pain relief. The routine of giving both a bolus dose and increasing the morphine dose at breakthrough pain should be encouraged. For the other patients studied, morphine infusions were considered to be adequate, but vomiting, nausea, and constipation might be reduced if prophylactic antiemetics and laxatives were given. Med Pediatr Oncol 2003;40:233–238. © 2003 Wiley‐Liss, Inc.
Degree of fatness after treatment of malignant lymphoma in childhood
Authors: Nysom Karsten , Holm Kirsten , Michaelsen Kim Fleischer , Hertz Henrik , Müller Jørn , Mølgaard Christian
Published: January 2003

Background

Sex hormone deficiency or growth hormone deficiency may cause excess fatness after treatment for childhood malignant lymphoma. Previous studies of the body composition after treatment for childhood cancer included few survivors of malignant lymphoma who were not analysed separately.

Procedure

We measured the whole‐body percent fat by dual energy X‐ray absorptiometry (DXA) and the body‐mass index (weight/height2 (kg/m2), BMI) in survivors of childhood Hodgkin disease (n = 23) or non‐Hodgkin lymphoma (n = 21) a median of 11 years after diagnosis (range 2–25). Results were compared with local data on 463 healthy controls.

Results

Adjusted for sex and age, the mean BMI did not differ from that of local controls, but the mean whole‐body percent fat was significantly increased (0.8 SD above predicted, P = 0.0001). Sixteen of 44 participants had a percent fat above the 90 percentile of the reference values, which indicates excess fatness. Adjusted for sex and age, percent fat was significantly higher in persons treated for non‐Hodgkin lymphoma. Controlled for this, the whole‐body percent fat was not significantly related to sex, age at diagnosis, length of follow‐up, sex hormone therapy at follow‐up or the cumulative dose of corticosteroids or doxorubicin.

Conclusions

Eleven years after diagnosis of childhood Hodgkin disease or non‐Hodgkin lymphoma, the whole‐body percent fat was increased whereas the BMI was like that of the controls. This indicates a reduced lean body mass. Med Pediatr Oncol 2003;40:239–243. © 2003 Wiley‐Liss, Inc.
Valid informed consent and participative decision‐making in children with cancer and their parents: A report of the SIOP working committee on psychosocial issues in pediatric oncology
Authors: Spinetta John J. , Masera Giuseppe , Jankovic Momcilo , Oppenheim Daniel , Martins Antonio Gentil , Ben Arush Myriam Weyl , van Dongen‐Melman Jeanette , Epelman Claudia , Medin Gabriela , Pekkanen Kirsti , Eden Tim
Published: January 2003

This is the tenth official document of the SIOP Working Committee on psychosocial issues in pediatric oncology, instituted in 1991. It is addressed to the pediatric oncology community. Children clearly have a right to participate in medical decisions regarding their own treatment, based on the developmental level of the child. The objective of these guidelines is to encourage physicians to share with the child developmentally relevant medical information specific to that particular child's health status, in the context of the child's own culture, so that he or she can actively participate in the decision‐making process regarding his or her own health. These guidelines, geared toward this objective, discuss the child's right to medical information, the parents' legal responsibility for but not exclusive right over the child's health, and ways of encouraging the younger child's active participation in his or her own health care at an age‐appropriate level of understanding. For adolescents, there should be a full and legally mandated power to make their own decisions regarding medical treatment. Med Pediatr Oncol 2003;40:244–246. © 2003 Wiley‐Liss, Inc.
Strength and functional mobility in children with acute lymphoblastic leukemia
Authors: Gocha Marchese Victoria , Chiarello Lisa A. , Lange Beverly J.
Published: January 2003

Background

The purposes of this pilot study were as follows: (1) to evaluate tools for measuring neuropathy in children with acute lymphoblastic leukemia (ALL), (2) to examine strength and functional mobility in children with ALL, and (3) to determine if there is a relationship between strength and function.

Procedure

Strength of knee extension and ankle dorsiflexion as measured with a dynamometer and functional mobility with the Timed Up and Go (TUG) were examined in eight children with ALL, ages 4–15 years, before and during delayed intensification (DI) therapy and in age‐ and gender‐matched controls.

Results

The mean knee extension strength, ankle dorsiflexion strength, and TUG measures for children with ALL before DI were significantly less than the means for the controls. The mean dorsiflexion strength measures for the children with ALL afte4 weeks of DI therapy were significantly lower than at time zero. Correlation of −0.794 (P = 0.05) was found between knee extension strength and TUG score for children with ALL.

Conclusions

The dynamometer and TUG are reliable tools to measure strength and function in children with ALL early in their treatment. In this study, ankle dorsiflexion strength worsened during DI therapy. There was a correlation between strength and function in children with ALL. Med Pediatr Oncol 2003;40:230–232. © 2003 Wiley‐Liss, Inc.
Hypothalamo‐pituitary‐adrenal axis integrity after cranial irradiation for childhood posterior fossa tumours
Authors: Spoudeas H.A. , Charmandari E. , Brook C.G.D.
Published: January 2003

Background

The evolution of anterior pituitary deficits after treatment for pituitary tumours has been largely attributed to local irradiation, but may be influenced as much by tumour mass or surgery. Other than growth hormone (GH) insufficiency, the late endocrinopathies after survival from non‐central brain tumours have been little documented. The aim of this study was to investigate the hypothalamic‐pituitary‐adrenal (HPA) axis in long‐term survivors of cranial irradiation for childhood posterior fossa tumours.

Procedure

We studied long‐term data in patients treated prepubertally for posterior fossa brain tumours and systematically referred by radiation oncologists for growth and pubertal monitoring to the London Centre for Paediatric Endocrinology over the last 25 years. They must have undergone HPA axis assessment twice, first prepubertally at documentation of growth failure, and second at completion of growth and puberty. Data on sixteen patients (12 males, 4 females; median age: 5.7 years, range: 2.5–8.8 years), who had undergone excision surgery with high dose cranial irradiation and/or chemotherapy for childhood posterior fossa tumours, were examined. Patients were followed for a median of 11.0 (range: 6.8–21.4) years after radiotherapy. HPA axis assessment was undertaken with the insulin‐induced hypoglycaemia test (ITT). Basal thyroid, cortisol and gonadal function tests were undertaken annually throughout the follow‐up period and any deficits replaced.

Results

At each ITT, all patients mounted an inadequate GH response. By the end of the follow‐up period all patients remained severely GH deficient, two (12.5%) had partial ACTH insufficiency, one (6.3%) had secondary hypothyroidism but none were gonadotropin deficient or hyperprolactinaemic.

Conclusions

Unlike the severe, evolving multiple pituitary deficits after treatment of pituitary or central tumours in adults, these findings in children with posterior fossa tumours suggest that, with the exception of GH, neurotoxicity due to irradiation per se is associated with a low prevalence of anterior pituitary hormone deficiencies, even at a long follow‐up. Since the children in this study were selected for assessment on the basis of growth failure, the high prevalence of GH insufficiency at first testing is to be expected; however, the early onset (within 1–3 years of irradiation) and permanence we have identified supports the view that GH is the most sensitive hormone to radiation injury. Med Pediatr Oncol 2003;40:224–229. © 2003 Wiley‐Liss, Inc.
Solid–liquid–air coupling in multiphase porous media
Authors: Laloui Lyesse , Klubertanz Georg , Vulliet Laurent
Published: January 2003

This paper addresses various issues concerning the modelling of solid–liquid–air coupling in multiphase porous media with an application to unsaturated soils. General considerations based on thermodynamics permit the derivation and discussion of the general form of field equations; two cases are considered: a three phase porous material with solid, liquid and gas, and a two phase porous material with solid, liquid and empty space. Emphasis is placed on the presentation of differences in the formulation and on the role of the gas phase. The finite element method is used for the discrete approximation of the partial differential equations governing the problem. The two formulations are then analysed with respect to a documented drainage experiment carried out by the authors. The merits and shortcomings of the two approaches are shown. Copyright © 2003 John Wiley & Sons, Ltd.
Olfactory neurons expressing identified receptor genes project to subsets of glomeruli within the antennal lobe of Drosophila melanogaster
Authors: Bhalerao Sheetal , Sen Anindya , Stocker Reinhard , Rodrigues Veronica
Published: January 2003

We have used green fluorescent protein to trace the projection patterns of olfactory neurons expressing identified candidate odorant receptors to the brain of Drosophila. At the periphery, receptor expression correlates with specific sense‐organ subtype, independent of location on the antennal surface. The majority of neurons expressing a given receptor converge onto one or two major glomeruli as described previously. However, we detected a few additional glomeruli, which are less intensely innervated and also tend to be somewhat variable. This means that functionally similar olfactory neurons connect to small subsets of glomeruli rather than to a single glomerulus as believed previously. This finding has important implications for our understanding of odor coding and the generation of olfactory behavior. © 2003 Wiley Periodicals, Inc. J Neurobiol 54: 577–592, 2003
Seasonal regulation of NMDA receptor NR2B mRNA in the adult canary song system
Authors: Singh Tryambak D. , Heinrich Julie E. , Wissman Anne M. , Brenowitz Eliot A. , Nordeen E. J. , Nordeen K. W.
Published: January 2003

Developmental changes in the composition and function of N‐methyl‐D‐aspartate receptors (NMDARs) are believed to regulate neural plasticity. For example, in songbirds, vocal learning entails NMDAR activation, and the sensitive period for such learning in zebra finches (ZFs) parallels developmental changes in NMDAR density and phenotype within several song‐related brain regions. In contrast to ZFs, canaries exhibit vocal plasticity recurrently throughout adulthood, prompted by seasonal changes in day length and testosterone (T) levels. We used in situ hybridization to determine if such changes in photoperiod affect NMDAR subunit expression in adult canaries. Birds were sacrificed while on short days (SD) when T levels were low, or on long days (LD) when T levels were high. Transcript levels for the constitutive NMDAR subunit (NR1) and two modulatory subunits (NR2A, NR2B) were measured in four song control nuclei: lMAN, Area X, HVc, and RA. NR1 and NR2A mRNA levels were comparable in SD and LD groups in all four song regions studied. However, NR2B mRNA levels within lMAN and RA were significantly higher in SD than in LD birds. Photoperiod did not affect NR2B transcript levels in Area X, HVc, or a nonsong region just lateral to lMAN. Our data support the hypothesis that changes in NMDAR subunit expression may contribute to the neural and behavioral reorganization that accompanies seasonal song remodeling in adulthood. © 2003 Wiley Periodicals, Inc. J Neurobiol 54: 593–603, 2003
Initial stages of neural regeneration in Helisoma trivolvis are dependent upon PLA2 activity
Authors: Geddis Matthew S. , Rehder Vincent
Published: January 2003

Neuronal regeneration after damage to an axon tract requires the rapid sealing of the injured plasma membrane and the subsequent formation of growth cones that can lead regenerating processes to their appropriate target. Membrane sealing and growth cone formation are Ca2+‐dependent processes, but the signaling pathways activated by Ca2+ to bring about these effects remain poorly understood. An in vitro injury model was employed in which neurites from identified snail neurons (Helisoma trivolvis) were transected with a glass microknife, and the formation of new growth cones from the distal portions of transected neurites was recorded at defined times after transection. This study presents three main results. First, phospholipase A2 (PLA2), a calcium‐activated enzyme, is necessary for membrane sealing in vitro. Second, PLA2 activity is also required for the formation of a new growth cone after the membrane has sealed successfully. Thus, PLA2 plays a dual role by affecting both growth cone formation and membrane sealing. Third, the injury‐induced activation of PLA2 by Ca2+ controls growth cone formation through the production of leukotrienes, secondary metabolites of PLA2 activity. Taken together, these results suggest that the injury‐induced Ca2+ influx acts via PLA2 and leukotriene production to assure growth cone formation. These findings indicate that events that cause an inhibition of PLA2 or lipoxygenases, enzymes that produce leukotrienes, could result in the inability of neurites to regenerate. © 2003 Wiley Periodicals, Inc. J Neurobiol 54: 555–565, 2003
Convergence of mechanosensory inputs onto neuromodulatory serotonergic neurons in the leech
Authors: Velázquez‐Ulloa N. , Blackshaw S. E. , Szczupak L. , Trueta C. , García E. , De‐Miguel F. F.
Published: January 2003

By the frequency‐dependent release of serotonin, Retzius neurons in the leech modulate diverse behavioral responses of the animal. However, little is known about how their firing pattern is produced. Here we have analyzed the effects of mechanical stimulation of the skin and intracellular stimulation of mechanosensory neurons on the electrical activity of Retzius neurons. We recorded the electrical activity of neurons in ganglia attached to their corresponding skin segment by segmental nerve roots, or in isolated ganglia. Mechanosensory stimulation of the skin induced excitatory synaptic potentials (EPSPs) and action potentials in both Retzius neurons in a ganglion. The frequency and duration of responses depended on the strength and duration of the skin stimulation. Retzius cells responded after T and P cells, but before N cells, and their sustained responses correlated with the activity of P cells. Trains of five impulses at 10 Hz in every individual T, P, or N cell in isolated ganglia produced EPSPs and action potentials in Retzius neurons. Responses to T cell stimulation appeared after the first impulse. In contrast, the responses to P or N cell stimulation appeared after two or more presynaptic impulses and facilitated afterward. The polysynaptic nature of all the synaptic inputs was shown by blocking them with a high calcium/magnesium external solution. The rise time distribution of EPSPs produced by the different mechanosensory neurons suggested that several interneurons participate in this pathway. Our results suggest that sensory stimulation provides a mechanism for regulating serotonin‐mediated modulation in the leech. © 2003 Wiley Periodicals, Inc. J Neurobiol 54: 604–617, 2003
Targeted gene expression in Drosophila dopaminergic cells using regulatory sequences from tyrosine hydroxylase
Authors: Friggi‐Grelin Florence , Coulom Hélène , Meller Margaret , Gomez Delphine , Hirsh Jay , Birman Serge
Published: January 2003

Dopamine (DA) is the only catecholaminergic neurotransmitter in the fruit fly Drosophila melanogaster. Dopaminergic neurons have been identified in the larval and adult central nervous system (CNS) in Drosophila and other insects, but no specific genetic tool was available to study their development, function, and degeneration in vivo. In Drosophila as in vertebrates, the rate‐limiting step in DA biosynthesis is catalyzed by the enzyme tyrosine hydroxylase (TH). The Drosophila TH gene (DTH) is specifically expressed in all dopaminergic cells and the corresponding mutant, pale (ple), is embryonic lethal. We have performed ple rescue experiments with modified DTH transgenes. Our results indicate that partially redundant regulatory elements located in DTH introns are required for proper expression of this gene in the CNS. Based on this study, we generated a GAL4 driver transgene, TH‐GAL4, containing regulatory sequences from the DTH 5′ flanking and downstream coding regions. TH‐GAL4 specifically expresses in dopaminergic cells in embryos, larval CNS, and adult brain when introduced into the Drosophila genome. As a first application of this driver, we observed that in vivo inhibition of DA release induces a striking hyperexcitability behavior in adult flies. We propose that TH‐GAL4 will be useful for studies of the role of DA in behavior and disease models in Drosophila. © 2003 Wiley Periodicals, Inc. J Neurobiol 54: 618–627, 2003
Activity alters muscle reinnervation and terminal sprouting by reducing the number of schwann cell pathways that grow to link synaptic sites
Authors: Love Flora M. , Son Young‐Jin , Thompson Wesley J.
Published: January 2003

In partially denervated rodent muscle, terminal Schwann cells (TSCs) located at denervated end plates grow processes, some of which contact neighboring innervated end plates. Those processes that contact neighboring synapses (termed “bridges”) appear to initiate nerve terminal sprouting and to guide the growth of the sprouts so that they reach and reinnervate denervated end plates. Studies conducted prior to knowledge of this potential involvement of Schwann cells showed that direct muscle stimulation inhibits terminal sprouting following partial denervation (Brown and Holland, 1979). We have investigated the possibility this inhibition results from an alteration in the growth of TSC processes. We find that stimulation of partially denervated rat soleus muscle does not alter the length or number of TSC processes but does reduce the number of TSC bridges. Stimulation also reduces the number of TSC bridges that form between end plates during reinnervation of a completely denervated muscle. The nerve processes (“escaped fibers”) that normally grow onto TSC processes during reinnervation are also reduced in length. Therefore, stimulation alters at least two responses to denervation in muscles: (1) the ability of TSC processes to form or maintain bridges with innervated synaptic sites, and (2) the growth of axons along processes extended by TSCs. © 2003 Wiley Periodicals, Inc. J Neurobiol 54: 566–576, 2003
Vitamin A deficiency leads to increased cell proliferation in olfactory epithelium of mature rats
Authors: Asson‐Batres M. A. , Zeng M.‐S. , Savchenko V. , Aderoju A. , McKanna J.
Published: January 2003

We have shown previously that vitamin A deficiency (VAD) leads to the decreased expression of gene products that are specifically synthesized by mature neurons in the olfactory epithelium (OE) of adult rats. These results support the hypothesis that retinoic acid, a derivative of vitamin A, is required for neurogenesis and neuron replacement in vivo. VAD does not cause gross degeneration of the OE, raising the question: what types of cells continue to populate VAD OE? In this study, we compared the cell densities of VAD and VA‐sufficient (VAS) OE and investigated whether cell proliferation is upregulated in VAD OE. The results show that (1) total cell number in VAD and VAS OE are comparable; (2) localized areas of hyperplasia are present in the basal regions of VAD, but not VAS, OE; (3) there is a substantial increase in the number of PCNA (proliferating cell nuclear antigen) positive cells in the basal region of VAD OE relative to VAS OE; and (4) there is a relative increase in the levels of mRNA encoding the transcription factor, MASH I, in VAD OE. We conclude that reduced availability of vitamin A derivatives, such as retinoic acid, leads to a loss of control over proliferation, hyperplasia, and increased numbers of pro‐neural cells in vivo. © 2003 Wiley Periodicals, Inc. J Neurobiol 54: 539–554, 2003
Estrogen regulates tyrosine hydroxylase expression in the neonate mouse midbrain
Authors: Ivanova Tatiana , Beyer Cordian
Published: January 2003

Estrogen plays an important role during differentiation of midbrain dopaminergic neurons. This is indicated by the presence of estrogen receptors and the transient expression of the estrogen‐forming enzyme aromatase within the dopaminergic cell groups. We have previously shown that estrogen regulates the plasticity of dopamine cells through the stimulation of neurite growth/arborization. In this study, we have analyzed the capability of estrogen to influence the activity of developing mouse dopamine neurons. The expression of tyrosine hydroxylase (TH) was assessed by competitive RT‐PCR and Western blotting. The developmental expression of TH in the ventral midbrain was studied from embryonic day 15 until postnatal day 15 and revealed highest TH levels early postnatally. This profile coincides with the transient aromatase expression in this brain area. Using cultured midbrain cells, we found that estrogen increased TH mRNA/protein levels. The application of the estrogen receptor antagonist ICI 182,780 resulted in a complete inhibition of estrogen effects. To verify these data in vivo, fetuses were exposed in utero from E15 until birth to the aromatase inhibitor CGS 16949A or to CGS supplemented with estrogen. CGS caused a robust reduction in TH mRNA/protein levels in the midbrain, which could be restored by estrogen substitution. Taken together, our data strongly suggest that estrogen controls dopamine synthesis in the developing nigrostriatal dopaminergic system and support the concept that estrogen is implicated in the regulation of ontogenetic steps but also in the function of midbrain dopamine neurons. © 2003 Wiley Periodicals, Inc. J Neurobiol 54: 638–647, 2003
Wasp venom blocks central cholinergic synapses to induce transient paralysis in cockroach prey
Authors: Haspel G. , Libersat F.
Published: January 2003

The parasitoid wasp Ampulex compressa induces a set of unique behavioral effects upon stinging its prey, the cockroach. It stings into the first thoracic segment inducing 2 to 3 min of transient flaccid paralysis of the front legs. This facilitates a second sting in the cockroach's head that induces 30 min of excessive grooming followed by a 2 to 5‐week long lethargic state. In the present study, we examine the immediate effect of the first sting, which is a transient paralysis of the front legs. Using radiolabeled wasps, we demonstrate that the wasp injects its venom directly into the cockroach's first thoracic ganglion. The artificial injection of milked venom into a thoracic ganglion abolishes spontaneous and evoked responses of the motoneurons associated with leg movements. To investigate the physiological mechanism of action of the venom, we injected venom into the last abdominal ganglion of the cockroach, which houses a well‐characterized cholinergic synapse. Injected venom abolishes both sensory‐evoked and agonist‐evoked postsynaptic potentials recorded in the postsynaptic neuron for 2 to 3 min without affecting action potential propagation. Thus, the venom blocking effect has a postsynaptic component that follows the same time course as the transient paralysis induced by the thoracic sting. Finally, injection of a nicotinic antagonist in the front thoracic ganglion induces paralysis of the front legs. We conclude that the transient paralytic effect of the thoracic sting can be mainly accounted for by the presence of a venom active component that induces a postsynaptic block of central cholinergic synaptic transmission. © 2003 Wiley Periodicals, Inc. J Neurobiol 54: 628–637, 2003
Time accurate consistently stabilized mesh‐free methods for convection dominated problems
Authors: Huerta Antonio , Fernández‐Méndez Sonia
Published: January 2003

The behaviour of high‐order time stepping methods combined with mesh‐free methods is studied for the transient convection–diffusion equation. Particle methods, such as the element‐free Galerkin (EFG) method, allow to easily increase the order of consistency and, thus, to formulate high‐order schemes in space and time. Moreover, second derivatives of the EFG shape functions can be constructed with a low extra cost and are well defined, even for linear interpolation. Thus, consistent stabilization schemes can be considered without loss in the convergence rates. Copyright © 2003 John Wiley & Sons, Ltd.
Guaranteed a posteriori error estimation for fully discrete solutions of parabolic problems
Authors: Strouboulis T. , Babuška I. , Datta D. K.
Published: January 2003

This paper addresses the construction of guaranteed computable estimates for fully discrete solutions of parabolic problems. Copyright © 2003 John Wiley & Sons, Ltd.
Particulate flow simulations using lubrication theory solution enrichment
Authors: Wagner G. J. , Ghosal S. , Liu W. K.
Published: January 2003

A technique for the numerical simulation of suspensions of particles in fluid based on the extended finite element method (X‐FEM) is developed. In this method, the particle surfaces need not conform to the finite element boundaries, so that moving particles can be simulated without remeshing. The finite element basis is enriched with the Stokes flow solution for flow past a single particle and the lubrication theory solution for flow between particles. The latter enrichment allows the simulation of particles that come arbitrarily close together without refining the mesh in the gap between them. Example problems illustrating both types of enrichment are shown, along with a study of a 50% solution in channel flow. Copyright © 2003 John Wiley & Sons, Ltd.
An improved crack analysis technique by element‐free Galerkin method with auxiliary supports
Authors: Lee Sang‐Ho , Yoon Young‐Cheol
Published: January 2003

In this study, an improved crack analysis technique by element‐free Galerkin method (EFGM) with auxiliary supports is proposed. To efficiently model the singularity and the discontinuity of the crack, a singular basis function which varies only on the auxiliary supports is added to enrich the standard EFG approximation and the discontinuous shape function is used in the vicinity of the crack surface. The proposed technique improves the accuracy in the near tip field, by using only an initial node arrangement without any modification until the completion of an analysis. A parametric study, which can guide the analyst on the reasonable choice for the formulation and modelling parameters to be used in the technique, is performed on a relative stress norm error and stress intensity factor. In addition, some numerical examples are analysed to verify the effectiveness of the proposed technique for a crack problem. Copyright © 2003 John Wiley & Sons, Ltd.
A non‐iterative finite element method for inverse heat conduction problems
Authors: Ling Xianwu , Keanini Russell G. , Cherukuri H. P.
Published: January 2003

A non‐iterative, finite element‐based inverse method for estimating surface heat flux histories on thermally conducting bodies is developed. The technique, which accommodates both linear and non‐linear problems, and which sequentially minimizes the least squares error norm between corresponding sets of measured and computed temperatures, takes advantage of the linearity between computed temperatures and the instantaneous surface heat flux distribution. Explicit minimization of the instantaneous error norm thus leads to a linear system, i.e. a matrix normal equation, in the current set of nodal surface fluxes. The technique is first validated against a simple analytical quenching model. Simulated low‐noise measurements, generated using the analytical model, lead to heat transfer coefficient estimates that are within 1% of actual values. Simulated high‐noise measurements lead to h estimates that oscillate about the low‐noise solution. Extensions of the present method, designed to smooth oscillatory solutions, and based on future time steps or regularization, are briefly described. The method's ability to resolve highly transient, early‐time heat transfer is also examined; it is found that time resolution decreases linearly with distance to the nearest subsurface measurement site. Once validated, the technique is used to investigate surface heat transfer during experimental quenching of cylinders. Comparison with an earlier inverse analysis of a similar experiment shows that the present method provides solutions that are fully consistent with the earlier results. Although the technique is illustrated using a simple one‐dimensional example, the method can be readily extended to multidimensional problems. Copyright © 2003 John Wiley & Sons, Ltd.
A gradient‐based adaptation procedure and its implementation in the element‐free Galerkin method
Authors: Luo Yunhua , Häussler‐Combe Ulrich
Published: January 2003

A gradient‐based adaptation procedure is proposed in this paper. The relative error in the total strain energy from two adjacent adaptation stages is used as a stop‐criterion. The refinement–coarsening process is guided by the gradient of strain energy density, based on the assumption: a larger gradient needs a richer mesh and vice versa. The procedure is then implemented in the element‐free Galerkin method for linear elasto‐static problems. Numerical examples are presented to show the performance of the proposed procedure. Copyright © 2003 John Wiley & Sons, Ltd.