bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of the Neurogranin Concentrated in Spines in the Induction of Long-Term Potentiation
Authors: Zhabotinsky Anatol M. , Camp R. Nicholas , Epstein Irving R. , Lisman John E.
Published: July 2006

Synaptic plasticity in CA1 hippocampal neurons depends on Ca2+elevation and the resulting activation of calmodulin-dependent enzymes. Induction of long-term depression (LTD) depends on calcineurin, whereas long-term potentiation (LTP) depends on Ca2+/calmodulin-dependent protein kinase II (CaMKII). The concentration of calmodulin in neurons is considerably less than the total concentration of the apocalmodulin-binding proteins neurogranin and GAP-43, resulting in a low level of free calmodulin in the resting state. Neurogranin is highly concentrated in dendritic spines. To elucidate the role of neurogranin in synaptic plasticity, we constructed a computational model with emphasis on the interaction of calmodulin with neurogranin, calcineurin, and CaMKII. The model shows how the Ca2+transients that occur during LTD or LTP induction affect calmodulin and how the resulting activation of calcineurin and CaMKII affects AMPA receptor-mediated transmission. In the model, knockout of neurogranin strongly diminishes the LTP induced by a single 100 Hz, 1 s tetanus and slightly enhances LTD, in accord with experimental data. Our simulations show that exchange of calmodulin between a spine and its parent dendrite is limited. Therefore, inducing LTP with a short tetanus requires calmodulin stored in spines in the form of rapidly dissociating calmodulin–neurogranin complexes.
Epidermal Growth Factor Receptor Activation: An Upstream Signal for Transition of Quiescent Astrocytes into Reactive Astrocytes after Neural Injury
Authors: Liu Bin , Chen Huiyi , Johns Terrance G. , Neufeld Arthur H.
Published: July 2006

Modulating the behaviors of reactive astrocytes is a potential therapeutic strategy for neurodegenerative diseases. We found that upregulation and activation of the epidermal growth factor receptor (EGFR) occur in astrocytes after different injuries in optic nervesin vivo. Activation of EGFR regulates genes and cellular processes representing most major markers of reactive astrocytes and genes related with glaucomatous optic neuropathy and other neural disorders. These results suggest that activation of EGFR is a common, regulatory pathway that triggers quiescent astrocytes into reactive astrocytes in response to neural injuries in the optic nerve, and perhaps other parts of the CNS. Targeting EGFR activation using an EGFR tyrosine kinase inhibitor prevents the loss of retinal ganglion cells in a model of glaucomatous optic neuropathy. Because these inhibitors are currently used clinically, our results present an approach to reactive astrocytes as a potential new target for the treatment of neurodegenerations.
The AFD Sensory Neurons Encode Multiple Functions Underlying Thermotactic Behavior inCaenorhabditis elegans
Authors: Clark Damon A. , Biron David , Sengupta Piali , Samuel Aravinthan D. T.
Published: July 2006

The thermotactic behaviors ofCaenorhabditis elegansindicate that its thermosensory system exhibits exquisite temperature sensitivity, long-term plasticity, and the ability to transform thermosensory input into different patterns of motor output. Here, we study the physiological role of the AFD thermosensory neurons by quantifying intracellular calcium dynamics in response to defined temperature stimuli. We demonstrate that short-term adaptation allows AFD to sense temperature changes as small as 0.05°C over temperature ranges as wide as 10°C. We show that a bidirectional thermosensory response (increasing temperature raises and decreasing temperature lowers the level of intracellular calcium in AFD) allows the AFD neurons to phase-lock their calcium dynamics to oscillatory thermosensory inputs. By analyzing the thermosensory response of AFD dendrites severed from their cell bodies by femtosecond laser ablation, we show that long-term plasticity is encoded as shifts in the operating range of a putative thermoreceptor(s) in the AFD sensory endings. Finally, we demonstrate that AFD activity is directly coupled to stimulation of its postsynaptic partner AIY. These observations indicate that many functions underlying thermotactic behavior are properties of one sensory neuronal type. Encoding multiple functions in individual sensory neurons may enableC. elegansto perform complex behaviors with simple neuronal circuits.
Time Course of Functional Connectivity between Dorsal Premotor and Contralateral Motor Cortex during Movement Selection
Authors: Koch Giacomo , Franca Michele , Fernandez Del Olmo Miguel , Cheeran Binith , Milton Rosemary , Alvarez Sauco Maria , Rothwell John C.
Published: July 2006

The left dorsal premotor cortex (PMd) is thought to play a dominant role in the selection of movements made by either hand. We used transcranial magnetic stimulation to study the functional connectivity of the left PMd and right primary motor cortex (M1) during an acoustic choice reaction time (RT) task involving contraction of the thumb and forefinger. The facilitatory and inhibitory pathways that can be demonstrated between left PMd and right M1 at rest were suppressed during most of the reaction period. However, they were activated briefly at the start of the reaction period, depending on whether the cue indicated that the forthcoming movement had to be made with the left or the right hand. The facilitatory pathway was active at 75 ms in those trials in which the subjects were required to move the left hand, whereas the inhibitory pathway was active at 100 ms in trials in which the subjects had to move the right hand. These changes in excitability did not occur in hand muscles not used in the task. There were no significant changes in the excitability of intracortical circuits [short intracortical inhibition (SICI) and intracortical facilitation (ICF)] in the right M1. Interhemispheric interactions between the right PMd and left M1 were mainly inhibitory at rest and showed the same temporal profile of interhemispheric inhibition as for left PMd–right M1, although no evidence was found for facilitatory interactions. The results illustrate the importance of PMd not only in facilitating cued movements but also in suppressing movements that have been prepared but are not used.
Combining an Autologous Peripheral Nervous System “Bridge” and Matrix Modification by Chondroitinase Allows Robust, Functional Regeneration beyond a Hemisection Lesion of the Adult Rat Spinal Cord
Authors: Houle John D. , Tom Veronica J. , Mayes Debra , Wagoner Gail , Phillips Napoleon , Silver Jerry
Published: July 2006

Chondroitinase-ABC (ChABC) was applied to a cervical level 5 (C5) dorsal quadrant aspiration cavity of the adult rat spinal cord to degrade the local accumulation of inhibitory chondroitin sulfate proteoglycans. The intent was to enhance the extension of regenerated axons from the distal end of a peripheral nerve (PN) graft back into the C5 spinal cord, having bypassed a hemisection lesion at C3. ChABC-treated rats showed (1) gradual improvement in the range of forelimb swing during locomotion, with some animals progressing to the point of raising their forelimb above the nose, (2) an enhanced ability to use the forelimb in a cylinder test, and (3) improvements in balance and weight bearing on a horizontal rope. Transection of the PN graft, which cuts through regenerated axons, greatly diminished these functional improvements. Axonal regrowth from the PN graft correlated well with the behavioral assessments. Thus, many more axons extended for much longer distances into the cord after ChABC treatment and bridge insertion compared with the control groups, in which axons regenerated into the PN graft but growth back into the spinal cord was extremely limited. These results demonstrate, for the first time, that modulation of extracellular matrix components after spinal cord injury promotes significant axonal regeneration beyond the distal end of a PN bridge back into the spinal cord and that regenerating axons can mediate the return of useful function of the affected limb.
TASK-Like Conductances Are Present within Hippocampal CA1 Stratum Oriens Interneuron Subpopulations
Authors: Torborg Christine L. , Berg Allison P. , Jeffries Brian W. , Bayliss Douglas A. , McBain Chris J.
Published: July 2006

TASK-1 (KCNK3) and TASK-3 (KCNK9) are members of the two-pore domain potassium channel family and form either homomeric or heteromeric open-rectifier (leak) channels. Recent evidence suggests that these channels contribute to the resting potential and input resistance in several neuron types, including hippocampal CA1 pyramidal cells. However, the evidence for TWIK-related acid-sensitive potassium (TASK)-like conductances in inhibitory interneurons is less clear, and mRNA expression has suggested that TASK channels are expressed in only a subpopulation of interneurons. Here we use immunocytochemistry to demonstrate prominent TASK-3 protein expression in both parvalbumin-positive- and a subpopulation of glutamic acid decarboxylase (GAD)67-positive interneurons. In addition, a TASK-like current (modulated by both pH and bupivacaine) was detected in 30–50% of CA1 stratum oriens interneurons of various morphological classes. In most neurons, basic shifts in pH had a larger effect on the TASK-like current than acidic, suggesting that the current is mediated by TASK-1/TASK-3 heterodimers. These data suggest that TASK-like conductances are more prevalent in inhibitory interneurons than previously supposed.
Cortical Inhibition Modified by Embryonic Neural Precursors Grafted into the Postnatal Brain
Authors: Alvarez-Dolado Manuel , Calcagnotto Maria Elisa , Karkar Kameel M. , Southwell Derek G. , Jones-Davis Dorothy M. , Estrada Rosanne C. , Rubenstein John L. R. , Alvarez-Buylla Arturo , Baraban Scott C.
Published: July 2006

Embryonic medial ganglionic eminence (MGE) cells transplanted into the adult brain can disperse, migrate, and differentiate to neurons expressing GABA, the primary inhibitory neurotransmitter. It has been hypothesized that grafted MGE precursors could have important therapeutic applications increasing local inhibition, but there is no evidence that MGE cells can modify neural circuits when grafted into the postnatal brain. Here we demonstrate that MGE cells grafted into one location of the neonatal rodent brain migrate widely into cortex. Grafted MGE-derived cells differentiate into mature cortical interneurons; the majority of these new interneurons express GABA. Based on their morphology and expression of somatostatin, neuropeptide Y, parvalbumin, or calretinin, we infer that graft-derived cells integrate into local circuits and function as GABA-producing inhibitory cells. Whole-cell current-clamp recordings obtained from MGE-derived cells indicate firing properties typical of mature interneurons. Moreover, patch-clamp recordings of IPSCs on pyramidal neurons in the host brain, 30 and 60 d after transplantation, indicated a significant increase in GABA-mediated synaptic inhibition in regions containing transplanted MGE cells. In contrast, synaptic excitation is not altered in the host brain. Grafted MGE cells, therefore, can be used to modify neural circuits and selectively increase local inhibition. These findings could have important implications for reparative cell therapies for brain disorders.
Sparse Representations for the Cocktail Party Problem
Authors: Asari Hiroki , Pearlmutter Barak A. , Zador Anthony M.
Published: July 2006

A striking feature of many sensory processing problems is that there appear to be many more neurons engaged in the internal representations of the signal than in its transduction. For example, humans have ∼30,000 cochlear neurons, but at least 1000 times as many neurons in the auditory cortex. Such apparently redundant internal representations have sometimes been proposed as necessary to overcome neuronal noise. We instead posit that they directly subserve computations of interest. Here we provide an example of how sparse overcomplete linear representations can directly solve difficult acoustic signal processing problems, using as an example monaural source separation using solely the cues provided by the differential filtering imposed on a source by its path from its origin to the cochlea [the head-related transfer function (HRTF)]. In contrast to much previous work, the HRTF is used here to separate auditory streams rather than to localize them in space. The experimentally testable predictions that arise from this model, including a novel method for estimating the optimal stimulus of a neuron using data from a multineuron recording experiment, are generic and apply to a wide range of sensory computations.
Pheromone Detection in Male Mice Depends on Signaling through the Type 3 Adenylyl Cyclase in the Main Olfactory Epithelium
Authors: Wang Zhenshan , Balet Sindreu Carlos , Li Vicky , Nudelman Aaron , Chan Guy C.-K. , Storm Daniel R.
Published: July 2006

Terrestrial vertebrates have evolved two anatomically and mechanistically distinct chemosensory structures: the main olfactory epithelium (MOE) and the vomeronasal organ (VNO). Although it has been generally thought that pheromones are detected through the VNO, whereas other chemicals are sensed by the MOE, recent evidence suggests that some pheromones may be detected through the MOE. Odorant receptors in the MOE are coupled to the type 3 adenylyl cyclase (AC3), an enzyme not expressed in the VNO. Consequently, odorants and pheromones do not elicit electrophysiological responses in the MOE of AC3−/−mice, although VNO function is intact. Here we report that AC3−/−mice cannot detect mouse milk, urine, or mouse pheromones. Inter-male aggressiveness and male sexual behaviors are absent in AC3−/−mice. Furthermore, adenylyl cyclase activity in membranes prepared from the MOE of wild-type mice, but not AC3−/−mice, is stimulated by 2-heptanone, a mouse pheromone. We conclude that signaling through AC3 in the MOE is obligatory for male sexual behavior, male–male aggressiveness, and the detection of some pheromones.
Effects of Reward and Behavioral Context on Neural Activity in the Primate Inferior Colliculus
Authors: Metzger Ryan R. , Greene Nathaniel T. , Porter Kristin Kelly , Groh Jennifer M.
Published: July 2006

Neural activity in the inferior colliculus (IC) likely plays an integral role in the processing of various auditory parameters, such as sound location and frequency. However, little is known about the extent to which IC neural activity may be influenced by the context in which sounds are presented. In this study, we examined neural activity of IC neurons in the rhesus monkey during an auditory task in which a sound served as a localization target for a saccade. Correct performance was rewarded, and the magnitude of the reward was varied in some experiments. Neural activity was also assessed during a task in which the monkey maintained fixation of a light while ignoring the sound, as well as when sounds were presented in the absence of any task. We report that neural activity increased late in the trial in the saccade task in 58% of neurons and that the level of activity throughout the trials could be modulated by reward magnitude for many neurons. The late-trial neural activity similarly increased in the fixation task in 39% of the neurons tested for this task but was not observed when sounds were presented in the absence of a behavioral task and reward. Together, these results suggest that a reward-related signal influences neural activity in the IC.
Photobiological Information Obtained from XPA Gene‐deficient Mice†
Authors: Horio Takeshi , Miyauchi‐Hashimoto Hiroko , Kuwamoto Kazue , Yamazaki Fumikazu , Okamoto Hiroyuki
Published: July 2006

The XPA gene‐deficient mouse, an animal model of xeroderma pigmentosum (XP), develops enhanced photobiologic reactions including acute inflammation, immunosuppression and skin carcinogenesis, because of the defect in the excision repair of ultraviolet‐induced DNA lesions. The results strongly suggest that nuclear DNA is an important chromophore to initiate acute and chronic skin damages. The model mouse is a useful experimental animal not only to investigate the mechanisms of photosensitivity in XP, but also to study physiological photobiology in humans, because photobiologic reactions are greatly intensified in this mouse.
Expression of sodium-iodide symporter mRNA in the thyroid gland of Xenopus laevis tadpoles: developmental expression, effects of antithyroidal compounds, and regulation by TSH
Authors: Opitz Robert , Trubiroha Achim , Lorenz Claudia , Lutz Ilka , Hartmann Sabine , Blank Tobias , Braunbeck Thomas , Kloas Werner
Published: July 2006

The uptake of iodide represents the first step in thyroid hormone synthesis by thyroid follicular cells and is mediated by the sodium-iodide symporter (NIS). In mammals, expression of NIS is stimulated by TSH and transcription of the NIS gene involves regulation by the thyroid-specific transcription factors Pax8 and Nkx2.1. In this study, we examined the mRNA expression of NIS, Pax8 and Nkx2.1 in the thyroid gland of Xenopus laevis tadpoles by semi-quantitative reverse transcriptase (RT)-PCR. During spontaneous metamorphosis, NIS mRNA expression was low in premetamorphic tadpoles, increased throughout prometamorphosis, and peaked at climax stage 60. Analysis of TSH β-subunit (TSHβ) mRNA in the pituitary of the same tadpoles revealed a close temporal relationship in the expression of the two genes during metamorphosis, suggesting a regulatory role of TSH in the developmental expression of NIS. Treatment of tadpoles with goitrogenic compounds (sodium perchlorate and ethylenethiourea) increased TSHβ mRNA expression (approximately twofold) and caused thyroid gland hyperplasia, confirming that feedback along the pituitary–thyroid axis was operative. Analysis of gene expression in the thyroid gland revealed that goitrogen treatment was correlated with increased expression of NIS mRNA (~20-fold). In the thyroid gland organ culture experiments, bovine TSH (bTSH; 1 mU/ml) strongly induced NIS mRNA expression. This effect was mimicked by co-culture of thyroid glands with pituitaries from stage 58 tadpoles and by agents that increase intracellular cAMP (forskolin, dibutyryl-cAMP). In addition, it could be shown that thyroid glands of X. laevis tadpoles express Pax8 and Nkx2.1 mRNA in a developmentally regulated manner and that ex vivo treatment of thyroid glands with bTSH, forskolin, and cAMP analogs increased the expression of Pax8 and Nkx2.1 mRNA. This is the first report on developmental profiles and hormonal regulation of thyroid gland gene expression in amphibian tadpoles and, together, results reveal a critical role of TSH in the regulation of NIS mRNA expression in the thyroid gland of X. laevis tadpoles.
Urocortin expression is downregulated in human endometrial carcinoma
Authors: Florio Pasquale , De Falco Giulia , Leucci Eleonora , Torricelli Michela , Torres Paulo B , Toti Paolo , Dell’Anna Arianna , Tiso Ennio , Santopietro Rosa , Leoncini Lorenzo , Petraglia Felice
Published: July 2006

Urocortin (UCN) is a 40-amino acid neuropeptide sharing 45% sequence homology with corticotropin-releasing factor (CRF). The human endometrium expresses both UCN and CRF, and CRF/UCN receptors type-1 (CRF-R1) and -2 (CRF-R2). CRF-R1 activation inhibits cell growth and proliferation of a tumor cell line derived from the human endometrium, and the UCN signaling pathway has been implicated in tumorigenesis of several tissues. Therefore, we investigated whether UCN mRNA and peptide are expressed by human endometrial adenocarcinoma, and whether their expression changes compared to controls. Samples of well (grade 1; n = 6 endometrioid adenocarcinoma, of whom n = 1 with squamous differentiation, and n = 1 clear-cell carcinoma) and poorly differentiated (grade 3; n = 3 endometrioid adenocarcinoma) endometrial adenocarcinoma were collected from nine women (age range 61–79 years) enrolled at the time of diagnosis. Healthy endometrium was collected from postmenopausal women (controls; n = 13; age range 64–78 years), who underwent hysterectomy for uterine prolapse. Immunohistochemistry was used to evaluate cellular UCN localization, with the intensity of immunostaining scored on a subjective scale. Quantitative real-time reverse transcriptase (RT)-PCR analysis was used to estimate mRNA expression changes and restriction analysis was used to confirm PCR products identity. UCN mRNA expression was significantly reduced (P < 0.0001) in endometrial adenocarcinoma than in healthy controls. Immunoreactive UCN was found in luminal and glandular epithelial cells in healthy, but not in neoplastic samples. UCN mRNA and peptide expressions are decreased in endometrial adenocarcinoma. These data and the evidence that endometrial cancer expresses UCN receptors and UCN is involved in tumorigenesis of several tissues together suggest a role for UCN in endometrial tumoral cell growth and proliferation.
Aging-related sex-dependent loss of the circulating leptin 24-h rhythm in the rhesus monkey
Authors: Downs Jodi L , Urbanski Henryk F
Published: July 2006

The adipocyte-derived hormone leptin plays a pivotal role in the regulation of body weight and energy homeostasis. Many studies have indicated that the circulating levels of leptin show a 24-h rhythm, but the exact cause and nature of this rhythm is still unclear. In the present study, we remotely collected blood samples every hour from young and old, male and female rhesus monkeys, and examined their 24-h plasma leptin profiles. In both the young males (10–11 years) and females (7–13 years), a clear 24-h plasma leptin rhythm was evident with a peak occurring ~4 h into the night and a nadir occurring ~1 h into the day (lights on from 0700 to 1900 h). A 24-h plasma leptin rhythm was also observed in the old males (23–30 years), even when they were maintained under constant lighting conditions (continuous dim illumination of ~100 lx). In marked contrast, plasma leptin concentrations were relatively constant across the day and night in old peri- and post-menopausal females (17–24 years), regardless of the lighting schedule. These data establish that rhesus monkeys, like humans, show a daily nocturnal rise in plasma leptin, and the magnitude of this rhythm undergoes a sex-specific aging-dependent attenuation. Furthermore, they suggest that the underlying endocrine mechanism may be driven in part by a circadian clock mechanism.
Conditional expression of hepatocyte nuclear factor-1β, the maturity-onset diabetes of the young-5 gene product, influences the viability and functional competence of pancreatic β-cells
Authors: Welters Hannah J , Senkel Sabine , Klein-Hitpass Ludger , Erdmann Silke , Thomas Heike , Harries Lorna W , Pearson Ewan R , Bingham Coralie , Hattersley Andrew T , Ryffel Gerhart U , Morgan Noel G
Published: July 2006

Mutations in the gene encoding hepatocyte nuclear factor (HNF)1β result in maturity-onset diabetes of the young-(MODY)5, by impairing insulin secretory responses and, possibly, by reducing β-cell mass. The functional role of HNF1β in normal β-cells is poorly understood; therefore, in the present study, wild-type (WT) HNF1β, or one of two naturally occurring MODY5 mutations (an activating mutation, P328L329del, or a dominant-negative form, A263insGG) were conditionally expressed in the pancreatic β-cell line, insulin-1 (INS-1), and the functional consequences examined. Surprisingly, overexpression of the dominant-negative mutant did not modify any of the functional properties of the cells studied (including insulin secretion, cell growth and viability). By contrast, expression of WT HNF1β was associated with a time- and dose-dependent inhibition of INS-1 cell proliferation and a marked increase in apoptosis. Induction of WT HNF1β also inhibited the insulin secretory response to nutrient stimuli, membrane depolarisation or activation of protein kinases A and C and this correlated with a significant decrease in pancrease-duodenum homeobox-1 protein levels. The attenuation of insulin secretion was, however, dissociated from the inhibition of proliferation and loss of viability, since expression of the P328L329del mutant led to a reduced rate of cell proliferation, but failed to induce apoptosis or to alter insulin secretion. Taken together, the present results suggest that mature rodent β-cells are sensitive to increased expression of WT HNF1β and they imply that the levels of this protein are tightly regulated to maintain secretory competence and cell viability.
Modulation of ACTH-induced cortisol release by polyunsaturated fatty acids in interrenal cells from gilthead seabream, Sparus aurata
Authors: Ganga R , Tort L , Acerete L , Montero D , Izquierdo M S
Published: July 2006

Highly unsaturated fatty acids are essential components of cellular membranes of vertebrates and can modulate physiological processes, including membrane transport, receptor function and enzymatic activities. In gilthead sea bream, dietary deficiencies of essential fatty acids of marine fish raise the basal cortisol levels and alter the pattern of cortisol release after stress. The aim of the present study was to clarify the effect of different essential fatty acids on adrenocorticotropic hormone (ACTH)-induced cortisol production and release in fish, through in vitro studies of sea bream interrenal cells maintained in superfusion and incubated with different types of fatty acids and eicosanoid production inhibitors. Results showed the first evidence of the effect of certain fatty acids on cortisol production by ACTH-stimulated interrenal cells in fish. Both arachidonic acid (ARA) and particularly eicosapentaenoic acid (EPA) promoted cortisol production in sea bream interrenal cells. Moreover, incubation with indometacin (INDO) reduced the increased cortisol production induced by EPA and ARA, suggesting mediation by their cyclooxygenase-derived products. Docosahexaenoic acid stimulated cortisol production to a lesser extent than that caused by EPA or ARA, but the inhibitory effect of INDO was not as marked as it was for the other fatty acids. In contrast, supplementation with dihomogammalinoleic acid reduced cortisol production, denoting the inhibitor effect of this fatty acid in cortisol secretion.
‘Effective inefficiency’: cellular control of protein trafficking as a mechanism of post-translational regulation
Authors: Conn P Michael , Janovick Jo Ann , Brothers Shaun P , Knollman Paul E
Published: July 2006

The great writer and polyglot, W Somerset Maugham said, ‘I’ll give you my opinion of the human race in a nutshell...their heart’s in the right place, but their head is a thoroughly inefficient organ.’ If his words are applied to trafficking of the human pituitary gonadotropin-releasing hormone receptor, it turns out that he was more right than he knew. Paradoxically, the inefficiency of receptor trafficking to the plasma membrane can bring regulatory advantages to cells. Understanding the mechanism by which cells recognize correctly folded proteins in health and disease opens doors to new therapeutic approaches and provides a more accurate view of mechanisms of normal cell function than is presently available.
Tissue-specific transcriptional initiation and activity of steroid sulfatase complementing dehydroepiandrosterone sulfate uptake and intracrine steroid activations in human adipose tissue
Authors: Valle L Dalla , Toffolo V , Nardi A , Fiore C , Bernante P , Di Liddo R , Parnigotto PP , Colombo L
Published: July 2006

Expression analysis by reverse transcriptase (RT)-PCR indicates that human adipose tissue is not likely to perform de novo synthesis of steroid hormones from cholesterol because the mRNAs of cytochromes P450scc and P450c17, and of the steroidogenic-related proteins, steroidogenic acute regulatory protein and steroidogenic factor 1, were not detected. Instead, our data support an intracrine role of adipose tissue, in which adrenal dehydroepiandrosterone sulfate (DHEA-S), the most abundant circulating androgen in man, is selectively uptaken, desulfated, and converted into bioactive androgens and estrogens. Three organic anion-transporting polypeptides-B, -D, and -E, presumably involved in DHEA-S transmembrane transport, were demonstrated at the mRNA level. While sulfotransferase expression was not found, the occurrence of steroid sulfatase (STS), converting DHEA-S to DHEA, was established at the mRNA, protein and catalytic activity levels. The 5′-rapid amplification of cDNA ends analysis showed that STS transcription in adipose tissue is regulated by the use of two promoters which differ from the prevalent placental one. The adipose transcripts contain a distinct untranslated first exon, 0a or 0b, followed by a common partially translated exon 1b, and nine other exons that are also shared by the main placental transcript. The presence of an upstream open reading frame in the new transcript variants could lead to an N-terminal divergence restricted to the cleavable signal peptide and thus not interfering with the catalytic activity of the mature STS protein. The adipose transcripts are also present in the placenta as minor isoforms. Western blotting revealed the characteristic ~64 kDa band of STS in both the placenta and adipose tissue. The specific enzymatic activity of STS in adipocytes was 118 pmol/106 cells per hour, about 50–100 times lower than in the placenta. A similar rate of [3H] DHEA-S uptake plus desulfation was measured in preadipo-cytes and adipocytes, equivalent to 40–45 pmol/106 cells per hour. Thus, an excessive accumulation of fat may out-compete other peripheral organs that are also dependent on intracrine DHEA-S utilization, especially when the adrenal production is low or declining with aging.
Hormonal regulation of cytochrome P450 aromatase mRNA stability in non-luteinizing bovine granulosa cells in vitro
Authors: Sahmi Malha , Nicola Edmir S , Price Christopher A
Published: July 2006

In the present study, we determined the potential for post-transcriptional regulation of cytochrome P450 aromatase (Cyp19), cytochrome P450 side-chain cleavage (Cyp11a) and 17β-hydroxysteroid dehydrogenase I (Hsd17b1) mRNA. Bovine granulosa cells were cultured in non-luteinizing conditions that permit long-term oestradiol secretion. Half-lives of mRNA were measured by Northern and/or reverse transcriptase (RT)-PCR after inhibition of gene transcription. In FSH-stimulated cells, the Cyp11a and Hsd17b1 mRNAs had half-lives greater than 12 h. The half-life of Cyp19 mRNA was significantly shorter at 3 h. The addition of the translation inhibitor cycloheximide to FSH-stimulated cells significantly increased Cyp19 mRNA half-life to approximately 12 h. Stimulation of cells with insulin resulted in Cyp19 mRNA half-life that was double (P<0.05) that in FSH-stimulated cells. We conclude that bovine Cyp19 mRNA is very labile under physiological conditions, and that Cyp19 expression is under hormonal control at a post-transcriptional level.
Social Capital: An Educational Panacea or a Challenge to the Way We Do Policy?
Authors: Healy Tom
Published: July 2006

This article focuses on these key themes: (1) the value of education as learning to be fully human, (2) the value of education as learning to be fully human with others and for others — inviting us to consider the concept of ‘social capital’ as a way of tapping into and releasing this value; and accordingly, (3) a number of practical considerations for how educational policy and practice can be influenced.
‘Different Children — A Tougher Job’. Icelandic Teachers Reflect on Changes in Their Work
Authors: Jóhannesson Ingólfur Ásgeir
Published: July 2006

This article is based on interviews with 67 primary school teachers and principals in Iceland about changes in the work of teachers during the last part of the twentieth century. The focus is on what teachers and principals understand as the most important change, how it affects teachers' work lives, and how they talk about change. The changes reported by the interviewees are ‘different children — a tougher job’, transformation in the roles of teachers and principals, increased cooperation between teachers and with other professionals, inclusion practices, more goal-governed versus book-governed teaching, and new methods of evaluation. These changes constitute a changing discourse of teachers about teaching, and they also have an impact on the work lives of teachers by creating tensions and contradictions similar to such tensions in other comparable countries.
Design, Development and Implementation of Inclusive Education
Authors: Mooij Ton , Smeets Ed
Published: July 2006

In inclusive education different pupils, including pupils with special educational needs and high ability pupils, can be stimulated to learn according to their capacities and potentials. The research question concentrates on the design features of inclusive education that will optimally promote the motivation and learning processes and outcomes of all pupils, and how relevant changes can be developed and implemented in educational practice. A model of guidelines concerning ‘multilevel contextual learning theory’ was expected to aid in designing psychologically appropriate learning processes and motivating educational, organisational, and managerial characteristics and procedures for all pupils. From 2003 to 2005, a pilot in which researchers and teachers collaborated was carried out in three Dutch pre-schools. Initial findings resulted in the development of a prototype of a pedagogical-didactic kernel or competence structure and a prototype of Internet-based software. Using these results, the screening of children's entry characteristics by infant day care teachers, parents, and preschool teachers was developed and implemented in practice. Construction and use of diagnostically based instructional, playing and learning procedures were first based on the screening results. The pre-schools differed much in rates of development and implementation. It is concluded that the proposed approach to the design, development and implementation of inclusive education that was applied seems promising in realising desired progress with pupils in early educational practice. However, policy and financial support are necessary to make more progress.
Umbilical Cord Stricture and Overcoiling are Common Causes of Fetal Demise
Authors: Peng Hong Qi , Smith-Levitin Michelle , Rochelson Burton , Kahn Ellen
Published: July 2006

Although umbilical cord stricture and umbilical cord overcoiling have been established as causes of intrauterine fetal demise, relatively few studies addressed this issue, most of them being case reports. We reviewed a total of 268 fetal autopsies during a 3-year period from 1998 to 2001. One hundred thirty nine cases of fetal demise including spontaneous abortion were identified. Nineteen percent (26 of 139) were associated with umbilical cord stricture, overcoiling, or a combination of both. Stricture of the umbilical cord was defined as a decrease in diameter in relation of the remaining umbilical cord; overcoiling as 0.3 coil/cm or greater. Fetal demise most commonly occurred in the second trimester, with a mean gestation age of 21 weeks. The average maternal age was 33 years; 15% had a prior fetal demise. We found that 77% (20 of 26) of these cases had umbilical cord stricture only or with overcoiling, 23% (6 of 26) had umbilical cord overcoiling alone. Localized deficiency of Wharton's jelly and increased collagen were found in all cases with umbilical cord stricture with or without overcoiling. In patients with umbilical cord overcoiling alone, 25% had Wharton's jelly deficiency; half of them had increased collagen deposition in the umbilical cords. The placenta was reviewed for secondary thrombosis of the vessels of the chorionic plate. Thrombosis of the vessels of the chorionic plate was noted in 54% of the patients. Our study suggests that umbilical cord stricture and cord overcoiling may represent two distinct pathological entities commonly causing fetal demise. This observation reinforces the importance of a fetal autopsy with careful examination of the placenta and umbilical cord with documentation of the cord coil index.
Hepatoblastomas and Liver Development: A Study of Cytokeratin Immunoexpression in Twenty-Nine Hepatoblastomas
Authors: Cajaiba Mariana Morais , Neves José Ivanildo , Casarotti Fabiana Facco , de Camargo Beatriz , ChapChap Paulo , Sredni Simone Treiger , Soares Fernando Augusto
Published: July 2006

Hepatoblastomas (HBs) recapitulate liver development. It is possible that HBs result from malignant transformation of hepatic precursor cells, and they may reflect a blockage in normal development. Here we study the expression of cytokeratins (CKs) in order to delineate the immunoprofile and relationship with liver development, as well as vimentin and alphafetoprotein (AFP), of HBs. Immunohistochemistry was performed in a tissue microarray (TMA) containing representative areas of 18 HBs (fetal and/or embryonal and/or mesenchymal); we also reviewed 11 cases not included in the TMA. No cases stained for CKs 1, 5/6, 7, 10, 13, 15, 16, 20, and 34βE12. CK8 stained 73.07% of fetal, 50% of embryonal, and 18% of mesenchymal areas. CK18 stained 100% of epithelial areas. CK19 staining was intense and diffuse in 100% of embryonal samples, but it was weaker in fetal areas (66.66%). AE1 stained epithelial areas in all cases, and it stained 29.41% of mesenchymal areas. AE3 stained 84.61% of embryonal and 60% of fetal components. AE1/AE3 showed stronger staining in embryonal (100%) than in fetal areas (76.92%). Vimentin staining was strong in embryonal (66.66%) and mesenchymal (84.61%) components but weak in fetal areas (8%). Alphafetoprotein was positive in only 20% of fetal and 70% of embryonal areas. Our results support the hypothesis that immunoexpression of HBs follows the stages of normal liver development. Embryonal areas look less differentiated, expressing vimentin and biliary epithelium CKs, whereas fetal areas display a more developed phenotype, similar to that of mature hepatocytes. These data aid in understanding the ontogenesis of HBs and may be used in histopathological diagnosis.
Fulminant Neonatal Liver Failure in Siblings: Probable Congenital Hemophagocytic Lymphohistiocytosis
Authors: Stapp Joan , Wilkerson Shirley , Stewart Dan , Coventry Susan , Mo Jun Qin , Bove Kevin E.
Published: July 2006

Familial hemophagocytic lymphohistiocytosis (HLH) is an autosomal recessive disorder of immune regulation characterized by fever, splenomegaly, cytopenia, hypertriglyceridemia, hypofibrinogenemia, and hyperferritinemia. Although presentation usually occurs during the first 2 years of life, congenital presentation is rare. We report siblings with a presumptive diagnosis of familial HLH who presented with hydrops fetalis and severe hepatic involvement ultimately resulting in their deaths. This report emphasizes the difficulty of confirming the diagnosis of HLH. However, establishing the diagnosis has important implications for genetic counseling and family planning. HLH should be considered in the setting of perinatal liver failure. The immunologic basis of the disease is incompletely understood but testing for natural killer cell function, and perforin defects may be helpful in establishing a diagnosis. HLH can be treated with chemotherapy, immunotherapy, and stem cell transplantation.
Amnion Degeneration over Fetal Placental Surface Vessels Possibly Resulting from Focal Hypoxia: A Case Report
Authors: Sato Yuichiro , Benirschke Kurt
Published: July 2006

The monoamnionic placenta of this twin gestation had focal amnion necrosis, but this was present only over the fetal surface vessels of one twin; this twin also developed cerebral atrophy. We hypothesize that this degeneration is due to a more severely reduced oxygen tension in its vessels. The placental amnion epithelium may undergo several degenerative processes, including amnion nodosum and changes due to meconium staining. Sonography had disclosed what appeared to be a dividing membrane, but this was not found at birth when monoamnionic twins with entangled cords presented. The amnion degeneration was present only over the large surface fetal vessels of the placenta of that twin who also developed central nervous system degeneration, and macrophage infiltration was confined to the same lesions. Focal hypoxia from entangling cords may have caused this defect.
Co-Occurrence of Massive Perivillous Fibrin Deposition and Chronic Intervillositis: Case Report
Authors: Weber Martin A. , Nikkels Peter G.J. , Hamoen Karen , Duvekot Johannes J. , de Krijger Ronald r.
Published: July 2006

Chronic intervillositis (CI) and massive perivillous fibrin deposition (MFD), together with its related entity, maternal floor infarction (MFI), are rare and poorly understood placental lesions. Both MFD/MFI and CI are associated with poor fetal outcome and high risk of recurrence. We report a patient who was found to have both MFD and CI in the same placenta, resulting in severe intrauterine fetal growth restriction and intrauterine fetal death at 37 weeks of gestation. Characteristic histological findings included both very extensive perivillous deposition of fibrinoid material and a heavy infiltrate of CD68-positive macrophages/monocytes in the maternal intervillous space. To our knowledge, this is the first time the co-occurrence of MFD and CI is reported in the literature.
Periventricular Leukomalacia: Overview and Recent Findings
Authors: Folkerth Rebecca D.
Published: July 2006

Periventricular leukomalacia (PVL), the main substrate for cerebral palsy, is characterized by diffuse injury of deep cerebral white matter, accompanied in its most severe form by focal necrosis. The classic neuropathology of PVL has given rise to several hypotheses about the pathogenesis, largely relating to hypoxia-ischemia and reperfusion in the sick premature infant. These include free radical injury, cytokine toxicity (especially given the epidemiologic association of PVL with maternofetal infection), and excitotoxicity. Among the recent findings directly in human postmortem tissue is that immunocytochemical markers of lipid peroxidation (hydroxy-nonenal and malondialdehyde) and protein nitration (nitrotyrosine) are significantly increased in PVL. Premyelinating oligodendrocytes, which predominate in periventricular regions during the window of vulnerability to PVL (24 to 34 postconceptional weeks), are the targets of this free radical injury, and suffer cell death. Susceptibility can be attributed, at least in part, to a relative deficiency of superoxide dismutases in the preterm white matter, including premyelinating oligodendrocytes. Several cytokines, including interferon-γ (known to be directly toxic to immature oligodendroglia in vitro), as well as tumor necrosis factor-α and interleukins 2 and 6, have been demonstrated in PVL. Microglia, which express toll-like receptors to bacterial products such as lipopolysaccharide, are increased in PVL white matter and may contribute to the injury. Preliminary work suggests a role for glutamate receptors and glutamate transporters in PVL, as has been seen in experimental animals. These findings pave the way for eventual therapeutic or preventive strategies for PVL.
Cytogenetic and p53 Profiles in Congenital Cystic Adenomatoid Malformation: Insights into its Relationship with Pleuropulmonary Blastoma
Authors: Vargas Sara O. , Korpershoek Esther , Kozakewich Harry P.W. , de Krijger Ronald R. , Fletcher Jonathan A. , Perez-Atayde Antonio R.
Published: July 2006

Congenital cystic adenomatoid malformation (CCAM), a developmental anomaly of lung, shares many features with the pediatric tumor pleuropulmonary blastoma (PPB). Both may show benign epithelium-lined cysts and mesenchymal proliferation, often with skeletal muscle differentiation. Before its recognition as a distinct entity, PPB was described in several reports as “rhabdomyosarcoma arising in CCAM.” Abnormal karyotypes in PPB often show excess material from chromosome 8. It has also been suggested that PPB may harbor p53 mutations. We examined the karyotype and searched for p53 mutations (via immunostaining and single-strand conformation polymorphism analysis) in 11 CCAM and in 2 PPB. Karyotypes were normal in all CCAM and showed clonal abnormalities in both PPB. There was marked and diffuse immunopositivity for nuclear p53 in the epithelial cells of CCAM and PPB. Strong staining was also observed in approximately 50% of the stromal cells in all PPB, but was seen in the stroma of only 2 of 10 CCAM, where it was faint and focal. TP53 mutations were not identified in CCAM or PPB. We conclude that CCAM does not contain the clonal chromosomal aberrations reported in PPB and shows less stromal p53 immunostaining than PPB. Since p53 mutations were not identified in either entity, the observed p53 immunoreactivity may be caused by another mechanism; its role in PPB and CCAM pathogenesis remains to be determined. Overall, these findings provide evidence that CCAM is nonneoplastic. Although some may view CCAM as a PPB precursor, it remains biologically distinct in terms of karyotype and p53 status.
High TGFβ1, Estrogen Receptor, and Aromatase Gene Expression in a Large Cell Calcifying Sertoli Cell Tumor (LCCSCT): Implications for the Mechanism of Oncogenesis
Authors: Saraco Nora , Berensztein Esperanza , Sciara Mariela , de Davila Maria T.G. , Ciaccio Marta , Ferrari Patricia , Belgorosky Alicia , Rivarola Marco A.
Published: July 2006

Large cell calcifying Sertoli cell tumors (LCCSCT) are associated with Carney complex and Peutz-Jeghers syndrome. The mechanisms linking these 2 genetic defects to the genesis of this tumor are obscure. Studies of CYP19 (aromatase) and transforming growth factor (TGF)–β1 messenger RNA (mRNA) abundance, estrogen receptor (ER), TGFβ1, and TGFβ type II receptor (R) immunochemistry were carried out in the testis of a patient with this tumor to gain information on possible mechanisms of cell tumor development. Testicular tissue of a prepubertal patient, collected at gonadectomy, was separated into 2 macroscopically distinct fractions: tumoral nodules (Tu) and extratumoral, normal-looking testicular tissue (ExTu). The patient was a 9.5-year-old boy with a 5-year history of bilateral gynecomastia (Tanner stage 4), no pubic hair, incipient genital development, and bilateral testicular nodules. Multiple pigmented lesions of the skin were present. Bilateral mammectomy and gonadectomy was performed. RNA was extracted from Tu and ExTu for semiquantitative reverse transcriptase–polymerase chain reaction of CYP19 and TGFβ1. Protein expression of ER, TGFβ1, and TGFβ type II R in Tu and ExTu was detected by immunohistochemistry. Cell proliferation was estimated by Ki-67 antigen immunochemistry and apoptosis using a modified TUNEL assay. Mean expression of aromatase and TGFβ1 mRNAs in Tu was 6- and 2.3-fold higher than in ExTu, respectively ( P < 0.05). Tumoral cells exhibited ER staining with a predominant extra-nuclear localization. Positive staining of Sertoli cells in Tu was higher than in ExTu. TGFβ1 immunostaining of the interstitial cells in Tu was higher than in ExTu. TGFβ type II R immunostaining was detected in most Sertoli and interstitial cells, but intensity in ExTu was lower than in Tu. No significant difference was detected in the proliferation index, but in Tu, the percentage of Sertoli cells in apoptosis (1.4%) was significantly lower ( P < 0.01) than in ExTu (14.0%). The following hypothesis is proposed. The congenital gene defects of Carney complex or of Peutz-Jeghers syndrome might trigger a cascade of intracellular events that leads to overexpression of aromatase in Sertoli cells, favoring the development of a LCCSCT. At some point in the evolution of the disease, a mutational event might induce a higher expression of the ER. Also, TGFβ1 protein expression is increased in neighboring cells. In this environment, TGFβ1 might switch from tumor suppressor to oncogenic factor and along with estrogen-ER complexes, might favor tumor progression by inhibiting apoptosis.