bluuebunny/crossref_metadata_2025 huggingface dataset:
Lack of pancreatic body and tail in HNF1B mutation carriers
Authors: Haldorsen I. S. , Vesterhus M. , Ræder H. , Jensen D. K. , Søvik O. , Molven A. , Njølstad P. R.
Published: July 2008

Aims  Hepatocyte nuclear factor 1B (HNF1B) gene mutation carriers have a systemic disease characterized by congenital malformations in the urogenital tract, diabetes mellitus of maturity‐onset diabetes of the young type and dysfunction of the liver and exocrine pancreas. We aimed to investigate pancreatic structure and exocrine function in carriers of HNF1B mutations.

Methods  We studied five subjects from two families with the previously reported mutation R137_K161del and the novel mutation F148L in HNF1B. All patients underwent computed tomography (CT) and magnetic resonance cholangiopancreatography (MRCP). We measured faecal elastase and serum vitamins D and E.

Results  One of the mutation carriers reported abdominal symptoms. All five subjects had faecal elastase deficiency, three had vitamin D deficiency and two had vitamin E deficiency. Neither CT nor MRCP depicted tissue corresponding to the pancreatic body and tail in the five mutation carriers, indicating agenesis of the dorsal pancreas. The head of the pancreas was slightly atrophic but had normal X‐ray attenuation at CT in all patients.

Conclusions  Agenesis of the pancreatic body and tail and pancreatic exocrine dysfunction are parts of the phenotype in HNF1B mutation carriers. This strengthens the evidence for a critical role of HNF1B in development and differentiation of at least the dorsal pancreas.
Ketoacidosis occurs in both Type 1 and Type 2 diabetes— a population‐based study from Northern Sweden
Authors: Wang Z. H. , Kihl‐Selstam E. , Eriksson J. W.
Published: July 2008

Aims  To determine the occurrence of diabetic ketoacidosis (DKA) in adult Type 2 and Type 1 diabetic patients in Northern Sweden and to determine whether DKA presents with a different clinical picture in Type 2 compared with Type 1 diabetic subjects.

Methods  All adult patients from a hospital catchment area in Northern Sweden with diagnosed DKA episodes during 1997–2000 were included in a retrospective study. Medical records and laboratory reports were analysed.

Results  During the years 1997 to 2000, the average annual incidence rate for DKA was 5.9 per 100 000 adult inhabitants. Twenty‐five patients developed DKA, eight (32%) had Type 2 diabetes, while 17 (68%) had Type 1 diabetes. Type 2 diabetic patients with DKA were older and had higher levels of C‐peptide than Type 1 diabetic patients. On admission because of DKA, a similar degree of hyperglycaemia was present in Type 1 and Type 2 patients. Metabolic acidosis was more severe in Type 1 compared with Type 2 diabetic patients. In 50% of the Type 2 diabetic patients, diabetes was diagnosed at the episode of DKA.

Conclusions  DKA occurs in Caucasian Type 2 diabetic patients within a Swedish population. Although the frequency of DKA is much higher in Type 1 diabetic patients, Type 2 diabetes may account for as much as one‐third of the overall DKA cases.
New use of rosiglitazone decreased following publication of a meta‐analysis suggesting harm
Authors: Shah B. R. , Juurlink D. N. , Austin P. C. , Mamdani M. M.
Published: July 2008

Aims  It is uncertain whether meta‐analyses lead to changes in prescribing practices. We studied trends in the prescribing of glucose‐lowering therapy before and after the publication of a meta‐analysis suggesting harm from rosiglitazone.

Methods  We examined the prescription records of all residents of Ontario, Canada, aged ≥ 66 years. For each week between January and December 2007, we identified new users of five categories of glucose‐lowering medications: rosiglitazone, pioglitazone, metformin, glibenclamide (glyburide) and insulin. The effect of the meta‐analysis was assessed using interventional autoregressive integrated moving‐average models.

Results  Following the release of the meta‐analysis, there was a sudden decline in new users of rosiglitazone (P = 0.01), mirrored by a nearly identical but transient increase in new users of pioglitazone (P < 0.001). There was also a net decline in new users of thiazolidinediones as a class (P < 0.001). The number of new users of other glucose‐lowering medications did not change.

Conclusions  A highly‐publicized meta‐analysis regarding rosiglitazone's potential harms led to an abrupt decline in new users of the drug, as well as a transient surge in new use of pioglitazone.
Levofloxacin‐associated hypoglycaemia complicated by pontine myelinolysis and quadriplegia
Authors: Vallurupalli S. , Huesmann G. , Gregory J. , Jakoby M. G.
Published: July 2008

Background  Central pontine myelinolysis (CPM) usually presents in chronic alcoholics and in patients in whom hyponatraemia has been corrected rapidly. However, CPM may occur in other clinical circumstances, including patients with severe hypoglycaemia. We describe the occurrence of CPM and quadriplegia in a patient who experienced fluoroquinolone‐associated severe hypoglycaemia.

Case report  A 63‐year‐old man with Type 2 diabetes mellitus was admitted to hospital for resection of a large liposarcoma. Renal‐dose levofloxacin was utilized as part of an antimicrobial regimen to treat post‐operative peritonitis. On days 6–8 of levofloxacin therapy, the patient experienced recurrent hypoglycaemia despite total parenteral nutrition, 10% dextrose containing fluids and cessation of insulin therapy 3 days prior to the first hypoglycaemic episode. Hypoglycaemia resolved within 24 h of stopping levofloxacin. After a final and severe hypoglycaemic event, the patient developed quadriplegia and tonic left deviation of gaze. Magnetic resonance imaging revealed a high‐intensity lesion in the central pons consistent with CPM.

Conclusions  Fluoroquinolones should be considered as a potential cause of hypoglycaemia. Severe hypoglycaemia has the potential to cause white matter lesions in the pons. Putative mechanisms include failure of membrane ion channels, oligodendrocyte apoptosis and oxidative stress of glucose reperfusion. Fluoroquinolone‐associated hypoglycaemia and hypoglycaemia‐induced quadriplegia are both rare and we believe this is the first case report linking the two events.
Increased levels of monokine induced by interferon‐γ (Mig) in the vitreous of patients with diabetic retinopathy
Authors: Wakabayashi Y. , Usui Y. , Okunuki Y. , Takeuchi M. , Kezuka T. , Iwasaki T. , Goto H.
Published: July 2008

Aim  To determine the intravitreous concentration of monokine induced by interferon‐γ (Mig) in patients with diabetic retinopathy (DR) and the relation between Mig and vascular endothelial growth factor (VEGF).

Research design and methods  Vitreous samples were obtained at the time of vitrectomy from 41 eyes of 38 DR patients (30 with active DR and 11 with inactive DR) and from 15 eyes of 15 non‐diabetic patients who had macular disease (control subjects). Human Mig and VEGF were quantified using a FACS Caliber® flow cytometer.

Results  The vitreous concentration of Mig was increased significantly in patients with both active and inactive DR [148.0 (31.6–997.2; median range) and 82.3 (25.7–347.7) pg/ml, respectively] compared with control subjects [21.0 (5.2–74.3) pg/ml; P < 0.0001 and P < 0.001, respectively]. In DR patients, a significant (P < 0.01) correlation was observed between vitreous concentrations of Mig and VEGF.

Conclusion  Our results suggest that Mig may play an important role in the pathogenesis of DR and works in consort with VEGF in the progression of pathological angiogenesis in DR.
Gender differences in the perception and acceptance of online games
Authors: Wang Hsiu‐Yuan , Wang Yi‐Shun
Published: July 2008

With the proliferation of online games, understanding users' intention to play online games has become a new issue for academics and practitioners. Prior studies have investigated the factors affecting behavioural intention to play online games. However, little research has been conducted to investigate the gender differences in the acceptance of online games. Thus, this study is to investigate the effects of perceived playfulness and its potential antecedents (ie, computer self‐efficacy, computer anxiety, challenge, speed and feedback) on the behavioural intention to play online games, and to examine the gender differences in the perception and acceptance of online games. Data collected from 281 respondents in Taiwan were tested against the research model using analysis of variance and structural equation modelling approaches. The theoretical and practical implications of the results were discussed.
Giving and receiving: measuring the carbon cost of mycorrhizas in the green orchid, Goodyera repens
Authors: Cameron Duncan D. , Johnson Irene , Read David J. , Leake Jonathan R.
Published: July 2008

DOI: 10.1111/j.1469-8137.2008.02610.xCommentary p 3
Deficits in early emotional reactivity in alexithymia
Authors: Pollatos Olga , Schubö Anna , Herbert Beate M. , Matthias Ellen , Schandry Rainer
Published: July 2008

Alexithymia is characterized by a difficulty in identifying and describing one's emotions. This study addressed the question of whether alexithymic tendencies are related to limited affective reactivity to briefly presented emotional stimuli. Skin conductance responses were assessed and backward masking was used to minimize elaborated processing of emotional pictures. Results indicated that alexithymic tendencies are associated with smaller electrodermal responses to briefly presented negative pictures. These effects were driven by difficulties in identifying and communicating emotions whereas externally orientated thinking was unrelated to affective reactivity. We conclude that there is an early processing deficit in response to negative stimuli in participants with high scores in alexithymia. Differences in the early emotional reactivity to arousing material could contribute to difficulties in emotional processes related to alexithymia.
The effects of achievement motivation, task difficulty, and goal difficulty on physiological, behavioral, and subjective effort
Authors: Capa Rémi L. , Audiffren Michel , Ragot Stéphanie
Published: July 2008

The purpose of the study was to present experimental arguments evaluating the Humphreys and Revelle's model of effort. Two important factors were tested: achievement motivation and difficulty. Heart rate, heart rate variability, blood pressure, facial electromyographic reactivity, and reaction time were measured as an index of effort expenditure. A 2 × 2 × 2 factorial design was used with two levels of resultant achievement motivation, two levels of task difficulty, and two levels of goal difficulty. As expected, the 16 participants high in resultant achievement motivation showed a better performance and had a larger decrease of the midfrequency band than the 16 participants low in resultant achievement motivation, especially during the difficult task. Results lend some support for the impact of resultant achievement motivation, task difficulty, and goal difficulty on effort mobilization.
Neuroanatomical correlates of aging, cardiopulmonary fitness level, and education
Authors: Gordon Brian A. , Rykhlevskaia Elena I. , Brumback Carrie R. , Lee Yukyung , Elavsky Steriani , Konopack James F. , McAuley Edward , Kramer Arthur F. , Colcombe Stanley , Gratton Gabriele , Fabiani Monica
Published: July 2008

Fitness and education may protect against cognitive impairments in aging. They may also counteract age‐related structural changes within the brain. Here we analyzed volumetric differences in cerebrospinal fluid and gray and white matter, along with neuropsychological data, in adults differing in age, fitness, and education. Cognitive performance was correlated with fitness and education. Voxel‐based morphometry was used for a whole‐brain analysis of structural magnetic resonance images. We found age‐related losses in gray and white matter in medial‐temporal, parietal, and frontal areas. As in previous work, fitness within the old correlated with preserved gray matter in the same areas. In contrast, higher education predicted preserved white matter in inferior frontal areas. These data suggest that fitness and education may both be predictive of preserved cognitive function in aging through separable effects on brain structure.
Intramodal and crossmodal processing delays in the attentional blink paradigm revealed by event‐related potentials
Authors: Ptito Alexia , Arnell Karen , Jolicœur Pierre , Macleod Jeffrey
Published: July 2008

In the attentional blink (AB), processing of a second target (T2) is impaired if it is presented shortly after the onset of a first target (T1), leading to a decrease in accurate report of T2 if T2 is masked. Some prominent theories of the AB suggest that an amodal bottleneck in working memory consolidation underlies the AB. We investigated this by factorially manipulating T1 and T2 modalities (visual or auditory) using equivalent stimuli and tasks in both modalities to minimize task switching. T2 was not masked. In all modality combinations, the electrophysiological P3 component to T2, obtained by subtracting T1 only trials from T1+T2 trials, was delayed and reduced in amplitude when T2 was presented soon after T1 relative to when T1 and T2 were presented farther apart. Results provide support for a common amodal bottleneck that underlies the AB effects observed in all visual/auditory modality combinations.
Comparative analysis of sialic acid levels in the colostrum and milk of ruminants: possible role in the passive immunity against neonatal infections
Authors: USEH NICODEMUS M , OLANIYAN OLABODE A , NOK ANDREW J
Published: July 2008

A study was conducted to determine the levels of free sialic acid in the colostrum and milk of apparently healthy indigenous Nigerian ruminants (Zebu cows, Yankassa sheep and Sokoto Red/Kano Brown goats). Haematological investigation indicates that the apparently healthy ruminants were also clinically healthy. The mean free sialic acid concentration in the colostrum of all the animal species examined was higher than those of milk and the difference in each case was statistically significant (P < 0.05). The significance of the high sialic acid level in colostrum for the immunity of neonates against microbial infections is discussed.
Gene transfer of PEDF attenuates ischemic brain damage in the rat middle cerebral artery occlusion model
Authors: Sanagi Tomomi , Yabe Takeshi , Yamada Haruki
Published: July 2008

Pigment epithelium‐derived factor (PEDF) is a 50‐kDa glycoprotein that protects various types of cultured neurons against neurotoxic stimuli, but its precise role in the CNS is not fully understood. In this study, we used rats whose brains were transfected to over‐express human PEDF in order to elucidate the neuroprotective effect of PEDF following transient middle cerebral artery occlusion (MCAO). A replication‐defective adenoviral vector containing the human PEDF gene (Ad.PEDF) or E. coliβ‐galactosidase (Ad.LacZ) was directly injected into the right striatum at 7 days prior to 70 min of MCAO in rats. Infarct volume and degree of edema of the Ad.PEDF‐treated group were significantly reduced compared to the Ad.LacZ‐treated group 24 h after MCAO. Degeneration of neurons, astrocytes, and oligodendrocytes caused by MCAO were attenuated by over‐expression of PEDF. The up‐regulation of pro‐inflammatory genes (TNFα, IL‐1β, IL‐6, COX‐2, and iNOS) and water channel aquaporin 4 after MCAO was significantly reduced in Ad.PEDF‐injected striatum. In conclusion, the results from this study provide the first in vivo evidence that PEDF is effective in protecting CNS neurons from ischemic insult, suggesting that PEDF may have a role as an endogenous neuroprotectant in the CNS.
c‐Abl is involved in high glucose‐induced apoptosis in embryonic E12.5 cortical neural progenitor cells from the mouse brain
Authors: Jia De‐yong , Du Zhan‐hui , Liu Shang‐ming , Liu Hui‐juan , Wang Fu‐wu , Ling Eng‐Ang , Liu Kai , Hao Ai‐jun
Published: July 2008

Hyperglycemia causes direct apoptosis of neural progenitor cells (NPCs) in diabetic‐induced neural tube defects in embryos. However, the underlying mechanisms are poorly understood. The present study is aimed to investigate the specific cellular proteins that may be involved in NPCs apoptosis as well as mechanisms by which the proteins regulate the oxidative stress‐induced NPCs apoptosis. Our present results have shown that the expression of c‐Abl was up‐regulated in NPCs exposed to high glucose in vitro. The increased c‐Abl was localized mainly in the nucleus. High glucose also induced an increase in nuclear p53 protein levels and the p53‐c‐Abl complex in NPCs. Administration of reactive oxygen species scavengers decreased the protein level of c‐Abl, p53 and NPCs apoptosis. Inhibition of c‐Abl reduced NPCs apoptosis and the nuclear protein level of p53 in response to high glucose. These results demonstrate that c‐Abl is involved in the reactive oxygen species‐activated apoptotic pathways in NPCs apoptosis. Inhibition of c‐Abl may protect NPCs against insults induced by high glucose via the modulation of NPCs apoptotic machinery.
Long‐term administration of cocaine or serotonin reuptake inhibitors results in anatomical and neurochemical changes in noradrenergic, dopaminergic, and serotonin pathways
Authors: Horne Malcolm K. , Lee Joohyung , Chen Feng , Lanning Katherine , Tomas Doris , Lawrence Andrew J.
Published: July 2008

The catechol and indole pathways are important components underlying plasticity in the frontal cortex and basal ganglia. This study demonstrates that administering rats either cocaine or a selective serotonin (or 5‐hydroxytryptamine; 5‐HT) reuptake inhibitor (SSRI) for 16 weeks results in reduced density of dopaminergic and noradrenergic terminals in the striatum and olfactory bulb, respectively, reflecting pruning of the terminal arbor of ventral midbrain dopaminergic and locus coeruleus noradrenergic neurones. In the striatum of cocaine‐treated animals, basal dopamine levels, as well as cocaine‐induced dopamine release, is diminished compared with controls. In contrast, serotonergic fibers, projecting from the raphe, sprout and have increased terminal density in the lateral septal nucleus and frontal cortex, following long‐term cocaine or SSRI treatment. This is associated with elevated basal 5‐HT and enhanced cocaine‐induced 5‐HT release in the frontal cortex. The anatomical and neurochemical changes in serotonergic fibers following cocaine or SSRI treatment may be explained by attenuated 5‐HT1Aautoreceptor function in the raphe. This study demonstrates extensive plasticity in the morphology and neurochemistry of the catechol and indole pathways that contribute to drug‐induced plasticity of the corticostriatal (and other) projections. Moreover, our data suggest that drug‐induced plastic adaptation is anatomically widespread and consequently, likely to have multiple and complex consequences.
Transregulation of leukemia inhibitor factor receptor expression and function by growth factors in neuroblastoma cells
Authors: Port Martha D. , Laszlo George S. , Nathanson Neil M.
Published: July 2008

The cytokines that signal through the leukemia inhibitory factor (LIF) receptor are members of the neuropoietic cytokine family and have varied and numerous roles in the nervous system. In this report, we have determined the effects of growth factor stimulation on LIF receptor (LIFR) expression and signal transduction in the human neuroblastoma cell line NBFL. We show here that stimulation of NBFL cells with either epidermal growth factor or fibroblast growth factor decreases the level of LIFR in an extracellular signal‐regulated kinase (Erk)1/2‐dependent manner and that this down‐regulation is due to an increase in the apparent rate of lysosomal LIFR degradation. Growth factor‐induced decreases in LIFR level inhibit both LIF‐stimulated phosphorylation of signal transducers and activators of transcription 3 and LIFR‐mediated gene induction. We also show that Ser1044 of LIFR, which we have previously shown to be phosphorylated by Erk1/2, is required for the inhibitory effects of growth factors. Neurons are exposed to varying combinations and concentrations of growth factors and cytokines that influence their growth, development, differentiation, and repair in vivo. These findings demonstrate that LIFR expression and signaling in neuroblastoma cells can be regulated by growth factors that are potent activators of the mitogen‐activated protein kinase pathway, and thus illustrate a fundamental mechanism that underlies crosstalk between receptor tyrosine kinase and neuropoietic cytokine signaling pathways.
Glutamate mobilizes [Zn2+]i through Ca2+‐dependent reactive oxygen species accumulation
Authors: Dineley Kirk E. , Devinney II Michael J. , Zeak Jennifer A. , Rintoul Gordon L. , Reynolds Ian J.
Published: July 2008

Liberation of zinc from intracellular stores contributes to oxidant‐induced neuronal injury. However, little is known regarding how endogenous oxidant systems regulate intracellular free zinc ([Zn2+]i). Here we simultaneously imaged [Ca2+]i and [Zn2+]i to study acute [Zn2+]i changes in cultured rat forebrain neurons after glutamate receptor activation. Neurons were loaded with fura‐2FF and FluoZin‐3 to follow [Ca2+]i and [Zn2+]i, respectively. Neurons treated with glutamate (100 μM) for 10 min gave large Ca2+ responses that did not recover after termination of the glutamate stimulus. Glutamate also increased [Zn2+]i, however glutamate‐induced [Zn2+]i changes were completely dependent on Ca2+ entry, appeared to arise entirely from internal stores, and were substantially reduced by co‐application of the membrane‐permeant chelator TPEN during the glutamate treatment. Pharmacological maneuvers revealed that a number of endogenous oxidant producing systems, including nitric oxide synthase, phospholipase A2, and mitochondria all contributed to glutamate‐induced [Zn2+]i changes. We found no evidence that mitochondria buffered [Zn2+]i during acute glutamate receptor activation. We conclude that glutamate‐induced [Zn2+]i transients are caused in part by [Ca2+]i‐induced reactive oxygen species that arises from both cytosolic and mitochondrial sources.
Activation of β‐catenin signalling by GSK‐3 inhibition increases p‐glycoprotein expression in brain endothelial cells
Authors: Lim Joseph C. , Kania Katarzyna D. , Wijesuriya Hasini , Chawla Sangeeta , Sethi Jaswinder K. , Pulaski Lukasz , Romero Ignacio A. , Couraud Pierre O. , Weksler Babette B. , Hladky Stephen B. , Barrand Margery A.
Published: July 2008

This study investigates involvement of β‐catenin signalling in regulation of p‐glycoprotein (p‐gp) expression in endothelial cells derived from brain vasculature. Pharmacological interventions that enhance or that block β‐catenin signalling were applied to primary rat brain endothelial cells and to immortalized human brain endothelial cells, hCMEC/D3, nuclear translocation of β‐catenin being determined by immunocytochemistry and by western blot analysis to confirm effectiveness of the manipulations. Using the specific glycogen synthase kinase‐3 (GSK‐3) inhibitor 6‐bromoindirubin‐3′‐oxime enhanced β‐catenin and increased p‐gp expression including activating the MDR1 promoter. These increases were accompanied by increases in p‐gp‐mediated efflux capability as observed from alterations in intracellular fluorescent calcein accumulation detected by flow cytometry. Similar increases in p‐gp expression were noted with other GSK‐3 inhibitors, i.e. 1‐azakenpaullone or LiCl. Application of Wnt agonist [2‐amino‐4‐(3,4‐(methylenedioxy) benzylamino)‐6‐(3‐methoxyphenyl)pyrimidine] also enhanced β‐catenin and increased transcript and protein levels of p‐gp. By contrast, down‐regulating the pathway using Dickkopf‐1 or quercetin decreased p‐gp expression. Similar changes were observed with multidrug resistance protein 4 and breast cancer resistance protein, both known to be present at the blood–brain barrier. These results suggest that regulation of p‐gp and other multidrug efflux transporters in brain vasculature can be influenced by β‐catenin signalling.
Neuroactive steroids and GABAAreceptor plasticity in the brain of the WAG/Rij rat, a model of absence epilepsy
Authors: Pisu Maria Giuseppina , Mostallino Maria Cristina , Dore Riccardo , Mura Maria Luisa , Maciocco Elisabetta , Russo Emilio , De Sarro Giovambattista , Serra Mariangela
Published: July 2008

The role of neuroactive steroids and GABAAreceptors in the generation of spontaneous spike‐and‐wave discharges (SWDs) was investigated in the WAG/Rij rat model of absence epilepsy. The plasma, cerebrocortical, and thalamic concentrations of the progesterone metabolite 3α‐hydroxy‐5α‐pregnan‐20‐one (3α,5α‐TH PROG) were increased in the WAG/Rij rat at 2 months of age compared with those in control (Wistar) rats. In contrast, the brain and peripheral levels of 3α,5α‐tetrahydrodeoxycorticosterone (3α,5α‐TH DOC) did not differ between the two rat strains at this age. At 6 months of age, when absence epilepsy worsens in WAG/Rij rats, the plasma concentration of 3α,5α‐TH PROG remained high whereas that of 3α,5α‐TH DOC had increased, the cerebrocortical levels of both 3α,5α‐TH PROG and 3α,5α‐TH DOC had increased, and the thalamic concentrations of these metabolites had decreased. At 6 months of age the expression of the α4and δ subunits of the GABAAreceptor in relay nuclei was increased. Finally, chronic stress induced by social isolation elicited a reduction in the amount of 3α,5α‐TH PROG in the thalamus of 2‐month‐old WAG/Rij rats that was associated with a reduction in the number and overall duration of SWDs at 6 months of age. Absence epilepsy in the WAG/Rij rat is thus associated with changes in the abundance of neuroactive steroids and in the expression of specific GABAAreceptor subunits in the thalamus, a brain area key to the pathophysiology of this condition.
Neurotrophin receptor homolog‐2 regulates nerve growth factor signaling
Authors: Wong Agnes W. , Willingham Melanie , Xiao Junhua , Kilpatrick Trevor J. , Murray Simon S.
Published: July 2008

The neurotrophin receptor homolog (NRH2) is closely related to the p75 neurotrophin receptor (p75NTR); however, its function and role in neurotrophin signaling are unclear. NRH2 does not bind to nerve growth factor (NGF), however, is able to form a receptor complex with tropomyosin‐related kinase receptor A (TrkA) and to generate high‐affinity NGF binding sites. Despite this, the mechanisms underpinning the interaction between NRH2 and TrkA remain unknown. Here, we identify that the intracellular domain of NRH2 is required to form an association with TrkA. Our data suggest extensive intracellular interaction between NRH2 and TrkA, as either the juxtamembrane or death domain regions of NRH2 are sufficient for interaction with TrkA. In addition, we demonstrate that TrkA signaling is dramatically influenced by the co‐expression of NRH2. Importantly, NRH2 did not influence all downstream TrkA signaling pathways, but rather exerted a specific effect, enhancing src homology 2 domain‐containing transforming protein (Shc) activation. Moreover, downstream of Shc, the co‐expression of NRH2 resulted in TrkA specifically modulating mitogen‐activated protein kinase pathway activation, but not the phosphatidylinositol 3‐kinase/Akt pathway. These results indicate that NRH2 utilizes intracellular mechanisms to not only regulate NGF binding to TrkA, but also specifically modulate TrkA receptor signaling, thus adding further layers of complexity and specificity to neurotrophin signaling.
Effects of advanced glycation end products‐inductor glyoxal and hydrogen peroxide as oxidative stress factors on rat retinal organ cultures and neuroprotection by UK‐14,304
Authors: Knels Lilla , Worm Maximilian , Wendel Martina , Roehlecke Cora , Kniep Eva , Funk Richard H. W.
Published: July 2008

Retinal ganglion cell degeneration is supposed to be mediated by reactive oxygen species (ROS) and advanced glycation end products (AGEs). The alpha2‐adrenergic agonist, 5‐bromo‐N‐(4,5‐dihydro‐1H‐imidazol‐2‐yl)‐6‐quinoxalinamine (brimonidine; UK‐14,304), is said to exert a neuroprotective effect. To investigate these mechanisms in detail, we exposed rat whole mounts to glyoxal or H2O2 and treated them with either UK‐14,304 alone or additionally with the phosphatidylinositide 3 kinase (PI3) kinase inhibitor, 2‐(4‐Morpholinyl)‐8‐phenyl‐4H‐1‐benzopyran‐4‐one (Ly 294002). The accumulation of Nε‐[carboxymethyl] lysine (CML) was assessed immunohistochemically and changes in intracellular pH (pHi), mitochondrial transmembrane potential (MTMP) and ROS production in cell bodies of multipolar ganglion cell layer were studied by intravital fluorescence microscopy and confocal laser scanning microscopy. Ultrastructural changes in mitochondria of multipolar ganglion cell layer cell bodies were determined by transmission electron microscopy. We found that glyoxal and H2O2 increased accumulation of CML‐modified proteins and ROS production and decreased pHi and MTMP in cell bodies of multipolar ganglion cell layer. UK‐14,304 could prevent production of ROS, accumulation of CML‐modified proteins, ameliorate acidification, preserve MTMP and attenuate ultrastructural damages of ganglion cell mitochondria. Ly 294002 reversed the UK‐14,304‐mediated attenuation of CML and ROS production. We conclude that the protective effects of UK‐14,304 seem partly to be mediated by PI3 kinase‐dependent pathways.
Neuromelanin can protect against iron‐mediated oxidative damage in system modeling iron overload of brain aging and Parkinson’s disease
Authors: Zecca Luigi , Casella Luigi , Albertini Alberto , Bellei Chiara , Zucca Fabio A. , Engelen Mireille , Zadlo Andrzej , Szewczyk Grzegorz , Zareba Mariusz , Sarna Tadeusz
Published: July 2008

In Parkinson’s disease (PD), dopamine neurons containing neuromelanin selectively degenerate. Neuromelanin binds iron and accumulates in aging. Iron accumulates in reactive form during aging, PD, and is involved in neurodegeneration. It is not clear how the interaction of neuromelanin and iron can be protective or toxic by modulating redox processes. Here, we investigated the interaction of neuromelanin from human substantia nigra with iron in the presence of ascorbic acid, dopamine, and hydrogen peroxide. We observed that neuromelanin blocks hydroxyl radical production by Fenton’s reaction, in a dose‐dependent manner. Neuromelanin also inhibited the iron‐mediated oxidation of ascorbic acid, thus sparing this major antioxidant molecule in brain. The protective effect of neuromelanin on ascorbate oxidation occurs even in conditions of iron overload into neuromelanin. The blockade of iron into a stable iron–neuromelanin complex prevents dopamine oxidation, inhibiting the formation of neurotoxic dopamine quinones. The above processes occur intraneuronally in aging and PD, thus showing that neuromelanin is neuroprotective. The iron–neuromelanin complex is completely decomposed by hydrogen peroxide and its degradation rate increases with the amount of iron bound to neuromelanin. This occurs in PD when extraneuronal iron–neuromelanin is phagocytosed by microglia and iron–neuromelanin degradation releases reactive/toxic iron.
Dietary flavonoid (−)epicatechin stimulates phosphatidylinositol 3‐kinase‐dependent anti‐oxidant response element activity and up‐regulates glutathione in cortical astrocytes
Authors: Bahia Parmvir K. , Rattray Marcus , Williams Robert J.
Published: July 2008

Flavonoids are plant‐derived polyphenolic compounds with neuroprotective properties. Recent work suggests that, in addition to acting as hydrogen donors, they activate protective signalling pathways. The anti‐oxidant response element (ARE) promotes the expression of protective proteins including those required for glutathione synthesis (xCT cystine antiporter, gamma‐glutamylcysteine synthetase and glutathione synthase). The use of a luciferase reporter (ARE‐luc) assay showed that the dietary flavan‐3‐ol (−)epicatechin activates this pathway in primary cortical astrocytes but not neurones. We also examined the distribution of NF‐E2‐related factor‐2 (Nrf2), a key transcription factor in ARE‐mediated gene expression. We found, using immunocytochemistry, that Nrf2 accumulated in the nuclei of astrocytes following exposure to tert‐butylhydroquinone (100 μM) and (−)epicatechin (100 nM). (−)Epicatechin signalling via Nrf2 was inhibited by wortmannin implicating a phosphatidylinositol 3‐kinase‐dependent pathway. Finally, (−)epicatechin increased glutathione levels in astrocytes consistent with an up‐regulation of ARE‐mediated gene expression. Together, this suggests that flavonoids may be cytoprotective by increasing anti‐oxidant gene expression.
Mammalian cerebral metabolism and amino acid neurotransmission during hibernation
Authors: Osborne Peter G. , Hashimoto Masaaki
Published: July 2008

This report demonstrates that during the torpor phase of hibernation, hamsters utilize 14C and 13C glucose in torpor‐specific brain metabolic pathways. Microdialysis of 14C glucose into the striatum rapidly induced a steady state labeling of extracellular fluid (ECF) lactate and labeling of tissue GABA, glutamate, glutamine, and alanine in ipsilateral and contralateral striata. The same tissue metabolites were labeled in cortex, hypothalamus, and brainstem after microdialysis of 14C lactate into the lateral ventricle. Serine, aspartate, glycine, taurine, tyrosine, and methionine were not synthesized from glucose or lactate during torpor. ECF levels of amino and organic acids were low and unchanging during torpor and increased late during arousal to cenothermia. Labeled intracellular 14C GABA and glutamate were not communicated to the striatal ECF or ventricular space during torpor. 13C NMR demonstrated rapid formation of lactate and functional tricarboxylic acid cycles in GABAergic and glutamatergic neurons, and enrichment of glutamine and alanine after i.v. 13C glucose. Large changes in tissue levels of amino acids occur prior to or during entrance into torpor but not during torpor. It is proposed that cerebral intracellular dehydration, the enlargement of ECF and the biochemistries associated with brain water homeostasis may have a role in regulating hibernation.
NCAM‐derived peptides function as agonists for the fibroblast growth factor receptor
Authors: Hansen Stine M. M. , Køhler Lene B. , Li Shizhong , Kiselyov Vladislav , Christensen Claus , Owczarek Sylwia , Bock Elisabeth , Berezin Vladimir
Published: July 2008

The neural cell adhesion molecule (NCAM) directly interacts with the fibroblast growth factor receptor (FGFR). Both fibronectin type III (FN3) modules of NCAM are involved in this interaction. One of the NCAM–FGFR contact sites has been localized recently to the upper N‐terminal part of the second NCAM FN3 module encompassing the F and G β‐strands and the interconnecting loop region. Here, we investigated whether any of the six putative strand‐loop‐strand regions in the first NCAM FN3 module are involved in FGFR interactions. Peptide sequences encompassing these regions, termed encamins, were synthesized and tested for their ability to bind and activate FGFR. Encamins localized to the N‐terminal part of the first FN3 module did not interact with FGFR, whereas encamins localized to the C‐terminal part, termed EncaminA, C and E, bound to and activated FGFR. The encamins induced FGFR‐dependent neurite outgrowth, and EncaminC and E promoted neuronal survival and enhanced pre‐synaptic function. In conclusion, the interaction between NCAM and FGFR probably involves multiple contact sites at an interface formed by the two NCAM FN3 modules and FGFR, and encamins could constitute important pharmacological tools for the study of specific functional aspects of NCAM, including neuroprotection and modulation of plasticity.
Over‐expression of Hsp27 does not influence disease in the mutant SOD1G93A mouse model of amyotrophic lateral sclerosis
Authors: Krishnan Jyothsna , Vannuvel Kayleen , Andries Maria , Waelkens Etienne , Robberecht Wim , Van Den Bosch Ludo
Published: July 2008

Amyotrophic lateral sclerosis (ALS) is a chronic, adult‐onset neurodegenerative disorder characterized by the selective loss of upper and lower motor neurons, resulting in severe atrophy of muscles and death. Although the exact pathogenic mechanism of mutant superoxide dismutase 1 (SOD1) causing familial ALS is still elusive, toxic protein aggregation leading to insufficiency of chaperones is one of the main hypotheses. In this study, we investigated the effect of over‐expressing one of these chaperones, heat shock protein 27 (Hsp27), in ALS. Mice over‐expressing the human, mutant SOD1G93A were crossed with mice that ubiquitously over‐expressed human Hsp27. Even though the single transgenic hHsp27 mice showed protection against spinal cord ischemia, the double transgenic SOD1G93A/hHsp27 mice did not live longer, and did not show a significant delay in the onset of disease compared to their SOD1G93A littermates. There was no protective effect of hHsp27 over‐expression on the motor neurons and on the mutant SOD1 aggregates in the double transgenic SOD1G93A/hHsp27 mice. In conclusion, despite the protective action against acute motor neuron injury, Hsp27 alone is not sufficient to protect against the chronic motor neuron injury due to the presence of mutant SOD1.
Neurofilament tail phosphorylation: identity of the RT‐97 phosphoepitope and regulation in neurons by cross‐talk among proline‐directed kinases
Authors: Veeranna  , Lee Ju‐Hyun , Pareek Tej K. , Jaffee Howard , Boland Barry , Vinod K. Yaragudri , Amin Niranjana , Kulkarni Ashok B. , Pant Harish C. , Nixon Ralph A.
Published: July 2008

As axons myelinate, establish a stable neurofilament network, and expand in caliber, neurofilament proteins are extensively phosphorylated along their C‐terminal tails, which is recognized by the monoclonal antibody, RT‐97. Here, we demonstrate in vivo that RT‐97 immunoreactivity (IR) is generated by phosphorylation at KSPXK or KSPXXXK motifs and requires flanking lysines at specific positions. extracellular signal regulated kinase 1,2 (ERK1,2) and pERK1,2 levels increase in parallel with phosphorylation at the RT‐97 epitope during early postnatal brain development. Purified ERK1,2 generated RT‐97 on both KSP motifs on recombinant NF‐H tail domain proteins, while cdk5 phosphorylated only KSPXK motifs. RT‐97 epitope generation in primary hippocampal neurons was regulated by extensive cross‐talk among ERK1,2, c‐Jun N‐terminal kinase 1,2 (JNK1,2) and cdk5. Inhibition of both ERK1,2 and JNK1,2 completely blocked RT‐97 generation. Cdk5 influenced RT‐97 generation indirectly by modulating JNK activation. In mice, cdk5 gene deletion did not significantly alter RT‐97 IR or ERK1,2 and JNK activation. In mice lacking the cdk5 activator P35, the partial suppression of cdk5 activity increased RT‐97 IR by activating ERK1,2. Thus, cdk5 influences RT‐97 epitope generation partly by modulating ERKs and JNKs, which are the two principal kinases regulating neurofilament phosphorylation. The regulation of a single target by multiple protein kinases underscores the importance of monitoring other relevant kinases when the activity of a particular one is blocked.
Native cone photoreceptor cyclic nucleotide‐gated channel is a heterotetrameric complex comprising both CNGA3 and CNGB3: a study using the cone‐dominant retina of Nrl−/− mice
Authors: Matveev Alexander V. , Quiambao Alexander B. , Browning Fitzgerald J. , Ding Xi‐Qin
Published: July 2008

Cone vision mediated by photoreceptor cyclic nucleotide‐gated (CNG) channel activation is essential for central and color vision and visual acuity. Mutations in genes encoding the cone CNG channel subunits, CNGA3 and CNGB3, have been linked to various forms of achromatopsia and progressive cone dystrophy in humans. This study investigates the biochemical components of native cone CNG channels, using the cone‐dominant retina in mice deficient in the transcription factor neural retina leucine zipper (Nrl). Abundant expression of CNGA3 and CNGB3 but no rod CNG channel expression was detected in Nrl−/− retina by western blotting and immunolabeling. Localization of cone CNG channel in both blue (S)‐ and red/green (M)‐cones was shown by double immunolabeling using antibodies against the channel subunits and against the S‐ and M‐opsins. Immunolabeling also showed co‐localization of CNGA3 and CNGB3 in the mouse retina. Co‐immunoprecipitation demonstrated the direct interaction between CNGA3 and CNGB3. Chemical cross‐linking readily generated products at sizes consistent with oligomers of the channel complexes ranging from dimeric to tetrameric complexes, in a concentration‐ and time‐dependent pattern. Thus this work provides the first biochemical evidence showing the inter‐subunit interaction between CNGA3 and CNGB3 and the presence of heterotetrameric complexes of the native cone CNG channel in retina. No association between CNGA3 and the cone Na+/Ca2+‐K+ exchanger (NCKX2) was shown by co‐immunoprecipitation and chemical cross‐linking. This may implicate a distinct modulatory mechanism for Ca2+ homeostasis in cones compared to rods.
NFκB in the mechanism of ammonia‐induced astrocyte swelling in culture
Authors: Sinke Anne P. , Jayakumar Arumugam R. , Panickar Kiran S. , Moriyama Mitsuaki , Reddy Pichili V. B. , Norenberg Michael D.
Published: July 2008

Astrocyte swelling and brain edema are major neuropathological findings in the acute form of hepatic encephalopathy (fulminant hepatic failure), and substantial evidence supports the view that elevated brain ammonia level is an important etiological factor in this condition. Although the mechanism by which ammonia brings about astrocyte swelling remains to be determined, oxidative/nitrosative stress and mitogen‐activated protein kinases (MAPKs) have been considered as important elements in this process. One factor known to be activated by both oxidative stress and MAPKs is nuclear factor κB (NFκB), a transcription factor that activates many genes, including inducible nitric oxide synthase (iNOS). As the product of iNOS, nitric oxide (NO), is known to cause astrocyte swelling, we examined the potential involvement of NFκB in ammonia‐induced astrocyte swelling. Western blot analysis of cultured astrocytes showed a significant increase in NFκB nuclear translocation (a measure of NFκB activation) from 12 h to 2 days after treatment with NH4Cl (5 mM). Cultures treated with anti‐oxidants, including superoxide dismutase, catalase, and vitamin E as well as the MAPKs inhibitors, SB239063 (an inhibitor of p38‐MAPK) and SP600125 (an inhibitor of c‐Jun N‐terminal kinase), significantly diminished NFκB activation by ammonia, supporting a role of oxidative stress and MAPKs in NFκB activation. The activation of NFκB was associated with increased iNOS protein expression and NO generation, and these changes were blocked by BAY 11–7082, an inhibitor of NFκB. Additionally, ammonia‐induced astrocyte swelling was inhibited by the NFκB inhibitors, BAY 11–7082 and SN‐50, thereby implicating NFκB in the mechanism of astrocyte swelling. Our studies indicate that cultured astrocytes exposed to ammonia display NFκB activation, which is likely to be a consequence of oxidative stress and activation of MAPKs. NFκB activation appears to contribute to the mechanism of ammonia‐induced astrocyte swelling, apparently through its up‐regulation of iNOS protein expression and the subsequent generation of NO.
Cisplatin‐mediated activation of extracellular signal‐regulated kinases 1/2 (ERK1/2) by inhibition of ERK1/2 phosphatases
Authors: Gozdz Agata , Vashishta Aruna , Kalita Katarzyna , Szatmari Erzsebet , Zheng Jing‐Juan , Tamiya Shigeo , Delamere Nicholas A. , Hetman Michal
Published: July 2008

The mechanism(s) underlying neurodegeneration‐associated activation of ERK1/2 remain poorly understood. We report that in cultured rat cortical neurons, whose basal ERK1/2 phosphorylation required NMDA receptors (NMDAR), the neurotoxic DNA intercalating drug cisplatin increased ERK1/2 phosphorylation via NMDAR despite reducing their activity. The rate of ERK1/2 dephosphorylation was lowered by cisplatin. Cisplatin‐treated neurons showed general transcription inhibition likely accounting for the reduced expression of the ERK1/2‐selective phosphatases including the dual specificity phosphatase‐6 (DUSP6) and the DUSP3 activator vaccinia‐related kinase‐3 (VRK3). Hence, cisplatin effects on ERK1/2 may be due to the deficient ERK1/2 inhibition by the transcription‐regulated phosphatases. Indeed, the transcription inhibitor actinomycin D reduced expression of DUSP6 and VRK3 while inducing the NMDAR‐dependent activation of ERK1/2 and the impairment of ERK1/2 dephosphorylation. Thus, cisplatin‐mediated transcriptional inhibition of ERK1/2 phosphatases contributed to delayed and long lasting accumulation of phospho‐ERK1/2 that was driven by the basal NMDAR activity. Our results provide the first direct evidence for transcriptionally‐regulated inactivation of neuronal ERK1/2. Its disruption likely contributes to neurodegeneration‐associated activation of ERK1/2.
The Notch signaling inhibitor DAPT down‐regulates cdk5 activity and modulates the distribution of neuronal cytoskeletal proteins
Authors: Kanungo Jyotshnabala , Zheng Ya‐Li , Amin Niranjana D. , Pant Harish C.
Published: July 2008

Notch signaling is critical for the development of the nervous system. Cyclin‐dependent kinase 5 (cdk5) is a neuronal kinase involved in neuronal development and phosphorylates a number of neuronal cytoskeletal proteins. To determine the relationship between Notch and cdk5 signaling, we tested the effects of the Notch inhibitor, N‐[N‐(3,5‐difluorophenacetyl)‐1‐alanyl]‐S‐phenylglycine t‐butyl ester (DAPT) on cdk5 expression, activity and cytoskeletal protein distribution in the rat cortical neurons in primary cultures. Neurons treated with 10 μM DAPT showed attenuated cdk5 activity in spite of an up‐regulation of cdk5 protein level, consistent with a phenomenon reported in the cdk5 transgenic mice. Immunoblot and immunofluorescence analyses showed an increased level of cdk5, but not p35. Phospho‐tau and phospho‐neurofilament showed a shift from axons to cell bodies in DAPT‐treated cells. DAPT‐induced attenuation of cdk5 activity was restored by over‐expression of p35 indicating that it interacted with cdk5 and up‐regulated nascent cdk5 activity. p35 over‐expression also rescued DAPT‐induced translocation of phospho‐tau and phospho‐neurofilament. Immunoprecipitation followed by immunoblotting demonstrated that DAPT does not disrupt cdk5 and p35 interaction. Moreover, DAPT up‐regulated neurogenin that is negatively regulated by Notch, and down‐regulated Hes1, a downstream target of Notch, suggesting that Notch signaling in the cortical neurons was disrupted. Semi‐quantitative and quantitative RT‐PCR analyses confirmed that DAPT up‐regulated cdk5 expression at the transcriptional level. These results establish a link between Notch signaling and cdk5 expression regulating neuronal cytoskeletal protein dynamics.