bluuebunny/crossref_metadata_2025 huggingface dataset:
Glutamate Dehydrogenase in Cerebellar Mutant Mice: Gene Localization and Enzyme Activity in Different Tissues
Authors: Miret‐Duvaux Odile , Frederic Florence , Simon Dominique , Guenet Jean‐Louis , Hanauer André , Delhaye‐Bouchaud Nicole , Mariani Jean
Published: December 2006

Abstract: Many similarities of both the inheritance pattern and the neuropathology can be observed between olivopontocerebellar atrophies, or so‐called multiple system atrophies (MSAs), and murine cerebellar mutations like Purkinje cell degeneration, nervous, staggerer, weaver, and reeler. Our study aimed to test whether the glutamate dehydrogenase (GDH) deficiency observed in some MSA patients could be found also in any of the murine mutants. GDH activity was assayed in several organs of these mutants, and no general deficiency was detected. By contrast, the level was found to be elevated in the cerebellum. The GDH gene was localized on mouse chromosome 14 and does not map close to any known neurological mutation in the mouse. We conclude, for the moment, that none of these cerebellar mutant mice can be considered as an animal model for GDH‐deficient MSA.
Characterisation of a Myristoyl CoA:Glycylpeptide N‐Myristoyl Transferase Activity in Rat Brain: Subcellular and Regional Distribution
Authors: McIlhinney R. A. Jeffrey , McGlone Kate
Published: December 2006

Abstract: An enzyme activity in rat brain, capable of catalysing the transfer of myristic acid from myristoyl CoA to the amino terminus of synthetic peptides, has been characterised. The synthetic peptides used as substrates were one based on the N‐terminal eight amino acids of cyclic AMP‐dependent protein kinase and another hexadecapeptide based on the N‐terminal sequence of p60src. This N‐myristoyl transferase (NMT) activity, which is both peptide dependent and heat labile, occurs in rat brain at levels at least three times those found in other rat tissues. In the presence of both ATP and CoA the enzyme catalysed the transfer of myristic acid, but not palmitic acid, specifically to the N‐terminal glycine of the peptides. Both peptide substrates exhibited Mi‐chaelis‐Menten kinetics yielding Km values of 100 μM and 60 μM, and Vmax values of 5 and 14.8 pmol/min/mg for the cyclic AMP‐dependent protein kinase peptide and sre‐derived peptides, respectively. The majority of the NMT activity was present in the cytosol of the brain homogenates, and there was evidence of an NMT inhibitory activity in both the particulate fraction of brain homogenates and in brain cytosol. NMT activity could also be demonstrated in the 100,000 g supernatant of lysed synaptosomes, and the synaptosomal membranes also exhibited an inhibitory activity on the soluble enzyme. Different brain areas exhibited different levels of the N‐myristoyl transferase activity and there was a fivefold difference in the activity found in the most active area, the hippocampus, compared to spinal cord.
Purification and Solubilization of Paired Helical Filaments from Alzheimer Brains
Authors: Vogelsang Glenn D. , Zemlan Frank P. , Dean Gary E.
Published: December 2006

Abstract: The purpose of the present study was to develop a purification and solubilization method, compatible with current amino acid sequencing techniques, for paired helical filaments (PHFs) derived from patients with Alzheimer's disease. We have developed a mild procedure that subjects conventionally isolated PHFs to Tris/borate/sodium dodecyl sulfate/2‐mercaptoethanol electrophoresis and results in the separation of the relatively insoluble PHF structures from both copurifying contaminating proteins and solubilized PHF‐associated proteins. At the end of 4.5 h of electrophoresis, the purified insoluble fraction had an amino acid composition that was invariant during subsequent electrophoresis. Electron microscopy revealed an intact PHF structure before and after electrophoresis but no evidence of any other structures in the insoluble fraction, a result consistent with the removal of PHF‐associated proteins from the filament structure. Isolated insoluble filament structures displayed an enhanced immunoreactivity with antibodies raised against purified PHFs in other laboratories, when compared with the fraction not subjected to electrophoresis in enzyme‐linked immunosorbent assays. Solubilization of the relatively insoluble PHFs was accomplished by extending the time of electrophoresis beyond the 4.5 h required for purification. Additional electrophoresis for 34.5 h solubilized 88% of the purified, relatively insoluble PHFs. This resulted in the identification of four major protein bands between Mr values of ∼50,000 and 70,000 on sodium dodecyl sulfate‐polyacrylamide electrophoresis gel analysis, with a predominant band with an Mr of ∼66,000. A slow fragmentation of the PHF ultrastructure occurred during this time, as judged by electron microscopy. This purification technique will permit the isolation of consistently reproducible protein fragments from solubilized PHFs, which may be used for subsequent sequence analysis.
Changes in the Ceramide Composition of Rat Forebrain Gangliosides with Age
Authors: Palestini P. , Masserini M. , Sonnino S. , Giuliani A. , Tettamanti G.
Published: December 2006

Abstract: Five major gangliosides (GM1, GD1a, GDlb, GTlb, and GQlb) were extracted and isolated by normal‐phase HPLC from the forebrain of Sprague‐Dawley rats of ages ranging from 3 days to 24 months. Each ganglioside was fractionated by reverse‐phase HPLC into the molecular species carrying a single long‐chain base moiety. At all ages, the C18:1 and C20:l long‐chain base species predominated, whereas the C18:0 and C20:0 ones represented 1–3% of the total. The C18:l long‐chain base species, predominant at 3 days (91–96%), diminished with age and reached, at 2 years, 73%, 65%, 61%, 59%, and 45% of the total for GDla, GM1, GTlb, GDlb, and GQlb, respectively. The content of the C20:1 long‐chain base species, low at birth (4–9%), increased with age in all gangliosides and reached, at 2 years, 27–55% of the total. The developmental behavior of the ganglioside species containing the C18:1 long‐chain base was characterized by the following: (a) a biphasic profile with a maximum around 15 days for GD1a, the most abundant ganglioside at all ages; (b) an increase until 6 months for GM1; (c) a sharp decrease until 30 days, followed by leveling for GTlb; and (d) a low, constant level for GDlb and GQlb. All the ganglioside species containing the C20:1 long‐chain base showed a constant increase during development, the increase being more marked in the first 30 days. The molecular species of all gangliosides carrying the C18:1 long‐chain base were virtually devoid of 20:0 fatty acids and carried a higher content of 18:0 fatty acids than the corresponding C20:l long‐chain base species (average 80 versus 57%). Moreover, in the C18:1 long‐chain base species, the 18:0 fatty acid content diminished with age from 89 to 72%, with a concurrent increase of 16:0 and 18:1 fatty acids, whereas the C20:l long‐chain base species had an age‐constant fatty acid composition.
Ammonium Injection Induces an N‐Methyl‐d‐Aspartate Receptor‐Mediated Proteolysis of the Microtubule‐Associated Protein MAP‐2
Authors: Felipo Vicente , Grau Eugenio , Miñana María‐Dolores , Grisolía Santiago
Published: December 2006

Abstract: We have shown previously that chronic hyperammonemia increases, in brain, the polymerization of microtubules that is regulated mainly by the level and state of phosphorylation of microtubule‐associated protein 2 (MAP‐2). Activation of the N‐methyl‐d‐aspartate (NMDA) receptor dephosphorylates MAP‐2. Because we have found that acute ammonia toxicity is mediated by the NMDA receptor, we have tested the effect of high ammonia levels on MAP‐2 in brain. Microtubules isolated from rats injected intraperitoneally with 6 mmol/kg ammonium acetate showed a marked decrease of MAP‐2. Also, the amount of MAP‐2 in brain homogenates, determined by immunoblotting. was markedly reduced, presumably by proteolysis. The content of MAP‐2 was decreased by ∼75% 1‐2 h after ammonium injection and returned to normal values after 4 h. Proteolysis of MAP‐2 was prevented completely by injection of 2 mg/kg MK‐801, a specific antagonist of the NMDA receptor, suggesting that proteolysis is mediated by activation of this receptor. l‐Carnitine, which protects rats against ammonia toxicity, also prevented MAP‐2 degradation. Because activation of the NMDA receptor increases [Ca2+]i, we determined whether rat brain contains a Ca2+‐dependent protease that selectively degrades MAP‐2. We show that there is a cytosolic Ca2+‐dependent protease that degrades MAP‐2, but no other brain proteins. The protease has been identified tentatively as calpain I, for it is inhibited by a specific inhibitor of this protease. Our results suggest that ammonium injection activates the NMDA receptor, leading to an increase in [Ca2+]i, which activates calpain I. This, in turn, selectively degrades MAP‐2. Possible implications in chronic hyperammonemic states and in the mechanism of ammonia toxicity are discussed.
CBP‐18, a Ca2+‐Binding Protein in Rat Brain: Tissue Distribution and Localization
Authors: Lipp H.‐P. , Wolfer D. P. , Qin W. X. , Klee C. B. , Heizmann C. W.
Published: December 2006

Abstract: The distribution of a novel calcium‐binding protein with a molecular mass of 18 kDa (CBP‐18) in the rat brain was studied by means of biochemical methods and immunohistochemistry on cryostat‐sectioned tissue and compared with staining patterns of parvalbumin on adjacent sections. The biochemical analysis revealed high levels of CPB‐18 in cortex and cerebellum, low levels in the lungs, and undetectable levels in all other tissues tested. Immunohistochemically, the polyclonal rabbit‐derived antibody for CPB‐18 showed selective affinity with periglomerular cells and dendrites in the olfactory bulb. Distinct immunostaining of scattered cells and their proximal dendrites was found in the anterior olfactory nuclei and in the perirhinal and entorhinal cortex. Strong staining of neuropil with recognizable but diffusely outlined cells was observed in the retrosplenial cortex, central amygdala, hippocampal rudiment, septum, area preoptica, hypothalamus, colliculus superior, and parabrachial nuclei. The cerebellum showed strong neuropil staining of both the molecular and the granule cell layer. Less intense neuropil staining and a few scattered cells were found in the neocortex, the remaining basal forebrain, and in the entire brainstem. Immunoreactivity was barely detectable or missing in the striatum, the hippocampus, the thalamus, and in the colliculus inferior. Thus, CPB‐18 shows a unique staining pattern in the CNS, different from all other Ca2+‐binding proteins studied so far.
In Vivo Brain Dialysis Study of the Somatodendritic Release of Serotonin in the Raphe Nuclei of the Rat: Effects of 8‐Hydroxy‐2‐(Di‐n‐Propylamino)tetralin
Authors: Adell Albert , Carceller Alicia , Artigas Francesc
Published: December 2006

Abstract: The characteristics of the serotonin (5‐HT) output in the dorsal and median raphe nuclei of the rat were studied using in vivo microdialysis. The basal output of 5‐HT increased after KC1 was added to the perfusion fluid. In contrast, neither the omission of calcium ions nor the addition of 0.5 nM tetrodotoxin affected dialysate 5‐HT or 5‐hy‐droxyindoleacetic acid (5‐H1AA). Reserpine did not decrease the output of 5‐HT and 5‐HIAA 24 h later and p‐chloroamphetamine increased 5‐HT in both vehicle‐ and reserpine‐treated rats severalfold. 8‐Hydroxy‐2‐(di‐n‐pro‐pylamino)tetralin (8‐OH‐DPAT), at 1 or 10 μM, perfused into the raphe did not change the outputs of 5‐HT or 5‐HIAA. Higher doses (0.1, Land 10 mM) increased extracellular 5‐HT in the raphe, probably via an inhibition of uptake. In animals bearing two probes (raphe nuclei and ventral hippocampus), only the 10 vaM dose of 8‐OH‐DPAT perfused into the raphe decreased the hippocampal output of 5‐HT and 5‐HIAA. The systemic injection of 0.1 mg/kg 8‐OH‐DPAT decreased dialysate 5‐HT and 5‐HIAA in the raphe and hippocampus. These results suggest that extracellular 5‐HT in raphe nuclei originates from a cytoplasmic pool and is not dependent on either nerve impulse of 5‐HT neurons or local activation of 5‐HT1A receptors.
Cerebral Aspartate Utilization: Near‐Equilibrium Relationships in Aspartate Aminotransferase Reaction
Authors: Erecińska Maria , Pleasure David , Nelson David , Nissim Itzhak , Yudkoff Marc
Published: December 2006

Abstract: The pathways of nitrogen transfer from 50 μM [15N]aspartate were studied in rat brain synaptosomes and cultured primary rat astrocytes by using gas chromatography‐mass spectrometry technique. Aspartate was taken up rapidly by both preparations, but the rates of transport were faster in astrocytes than in synaptosomes. In synaptosomes, 15N was incorporated predominantly into glutamate, whereas in glial cells, glutamine and other 15N‐amino acids were also produced. In both preparations, the initial rate of N transfer from aspartate to glutamate was within a factor of 2‐3 of that in the opposite direction. The rates of transamination were greater in synaptosomes than in astrocytes. Omission of glucose increased the formation of [15N]‐glutamate in synaptosomes, but not in astrocytes. Rotenone substantially decreased the rate of transamination. There was no detectable incorporation of 15N from labeled aspartate to 6‐amino‐15N‐labeled adenine nucleotides during 60‐min incubation of synaptosomes under a variety of conditions; however, such activity could be demonstrated in glial cells. The formation of 15N‐labeled adenine nucleotides was marginally increased by the presence of 1 mM aminooxyacetate, but was unaffected by pretreatment with 1 mM 5‐amino‐4‐imidazolecarboxamide ribose. It is concluded that (1) aspartate aminotransferase is near equilibrium in both synaptosomes and astrocytes under cellular conditions, but the rates of transamination are faster in the nerve endings; (2) in the absence of glucose, use of amino acids for the purpose of energy production increases in synaptosomes, but may not do so in glial cells because the latter possess larger glycogen stores; and (3) nerve endings have a very limited capacity for salvage of the adenine nucleotides via the purine nucleotide cycle.
Identification and Characterization of Protein Kinase FA/ Glycogen Synthase Kinase 3 in Clathrin‐Coated Brain Vesicles
Authors: Yu Jau‐Song , Yang Shiaw‐Der
Published: December 2006

Abstract: Mg‐ATP‐dependent protein phosphatase activating factor [kinase FA/glycogen synthase kinase 3 (GSK‐3)] has been identified in highly purified clathrin‐coated vesicles (CCVs) isolated from pig brain. Kinase FA was found to exist in an inactive state but can be activated by 1% Triton X‐100 or [M/Tris‐HC] extraction in brain CCVs. Activation of kinase FA in CCVs is due to disassociation of the kinase from CCVs as demonstrated on sucrose density‐gradient ultracentrifugation and Sepharose CL‐4B gel filtration. Using purified brain CCVs as substrates, kinase FA enhanced the endogenous phosphorylation of assembly protein complexes in the molecular weight range of 100,000‐130,000 severalfold, as demonstrated by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis followed by autoradiography. Comparisons with well‐defined brain CCV‐associated endogenous protein kinases such as pp50 kinase/AP50 and casein kinase 2 provide evidence that kinase FA/GSK‐3 represents a third potent and unique CCV‐associated protein kinase distinctly different from the previously described CCV protein kinases, suggesting the possible involvement of kinase FA in the regulation of CCV functions in the brain. The results also support the notion that protein kinase FA is involved in cell surface signal transduction in the CNS.
Casein Kinase II Activity in the Postischemic Rat Brain Increases in Brain Regions Resistant to Ischemia and Decreases in Vulnerable Areas
Authors: Hu Bing Ren , Wieloch Tadeusz
Published: December 2006

Abstract: Casein kinase II (CKII) is a protein kinase acting in the intracellular cascade of reactions activated by growth factor receptors, and that has a profound influence on cell proliferation and survival. In this investigation, we studied the changes in the activity and levels of CKII in the rat brain exposed to 10. 15 and 20 min of transient forebrain ischemia followed by variable periods of reperfusion. The cytosolic CKII activity decreased during reperfusion by ∼ 30 and ∼ 50% in the selectively vulnerable areas, striatum and the CA1 region of the hippocampus, respectively. In the resistant CA3 region of hippocampus and neocortex, the activity increased by ∼ 20 and ∼ 60%, respectively. The postischemic changes in CKII activity were dependent on the duration of the ischemic insult. The levels of CKII did not change after ischemia, suggesting that the enzyme is modulated by covalent modification or is interacting with an endogenous inhibitor/activator. Treatment of the cytosolic fraction from cortex of rats exposed to ischemia and 1 h of reperfusion with agarose‐bound phosphatase decreased the activity of CKII to control levels, suggesting that CKII activation after ischemia involves a phosphorylation of the enzyme. The correlation between postischemic CKII activity and neuronal survival implies that preservation or activation of CKII activity may be important for neuronal survival after cerebral ischemia.
Opioid Peptides in the Rabbit Carotid Body: Identification and Evidence for Co‐Utilization and Interactions with Dopamine
Authors: González‐Guerrero P. R. , Rigual R. , González C.
Published: December 2006

Abstract: The rabbit carotid body is a catecholaminergic organ that contains dopamine and norepinephrine in a proportion of nearly 5:1. Chronic (15 days) carotid sinus nerve denervation or superior cervical ganglionectomy did not modify the carotid body dopamine content (5–6 nmol/mg of protein, equivalent to 250 pmol per carotid body), but sympathectomy reduced by ∼ 50% the norepinephrine content. The carotid body has also a very high content of opioid activity (250 equivalent pmol of Leu‐enkephalin/mg of protein) as measured by a radioreceptor assay that detects preferentially δ‐opioid activity. In the carotid body the degree of opioid posttranslational processing to low‐molecular‐weight peptides (mostly Leu‐ and Met‐enkephalin) is nearly 80%. HPLC identification of opioid peptides revealed that the sequences of Met‐ and Leu‐enkephalin were in a proportion of nearly 6:1, indicating that the main opioid precursor in the carotid body is proenkephalin A. Chronic denervations of the carotid body did not modify the levels or the degree of opioid precursor processing. Acute hypoxic exposure of the animals (8% 02 in N2; 3 h) resulted in a parallel decrease of dopamine and opioid activity, without any change in the degree of opioid processing. Norepinephrine levels were not affected by hypoxia. These findings suggest corelease of dopamine and opioids during natural hypoxic stimulation. In agreement with the analytical data. [d‐Ala2, d‐Leu5]enkephalin, but not [d‐Ala2,N‐Me‐Phe4 Gly5‐ol]‐enkephalin, reduced the in vitro release of dopamine induced by low Po2, a high external K+ concentration, and dinitrophenol. Naloxone augmented the release response elicited by low Po2 stimulation. These findings indicate that the previously described inhibitory actions of opioids are mediated, at least in part, by receptors located in chemoreceptor cells. Additional targets for opioid peptides, e.g., sensory nerve endings or blood vessels, and additional actions of opioids on chemoreceptor cells, e.g., long‐term trophic actions, are not excluded.
Effects of Chronic Hypoxia on Opioid Peptide and Catecholamine Levels and on the Release of Dopamine in the Rabbit Carotid Body
Authors: González‐Guerrero P. R. , Rigual R. , González C.
Published: December 2006

Abstract: Carotid body catecholamine and opioid levels were measured in rabbits exposed for 8 days to an atmosphere of 11% O2 in N2 (Po2 of ∼ 80 mm Hg) and during an identical period of recovery, i.e., after 8 days of returning to the control normoxic atmosphere. Carotid bodies show a decrease in dopamine content at day 2. Thereafter, the levels of this biogenic amine increase progressively to peak at day 10, that is, 2 days after returning to a normoxic atmosphere. Finally, dopamine levels start to decrease and reach prehypoxic control levels at day 16, that is, after 8 days of recovery. In contrast, levels of native opioid peptides remain unchanged during the whole duration of the experiment, except for a decrease at day 2 of the hypoxic exposure. Levels of total opioid peptides are also below control values at day 2 of hypoxia, increase above control values on returning to a normoxic atmosphere (maximal levels at days 10‐12), and later decrease to reach prehypoxic levels at day 16. As a result of these changes the ratios of dopamine to opioid levels show a progressive increase from day 0 to day 10 of the experiment and then return to control prehypoxic values. Carotid bodies isolated from animals that have been exposed to hypoxia for 8 days synthesize [3H]dopamine from its natural precursor [3H]tyrosine at a rate of 175 pmol/mg of protein/h, which is about double the rate of synthesis found in the carotid bodies of control animals and those allowed to recover for 8 days. The release of [3H]‐dopamine induced by mild hypoxic stimuli and by a high external K+ concentration is greater in the carotid bodies isolated from animals hypoxic for 8 days than in those of control animals (catecholamine deposits were labeled by prior incubation with [3H]tyrosine); in contrast, the carotid bodies from chronically hypoxic animals exhibit an attenuated release response to intense hypoxic stimuli and to dinitrophenol. Stimulus‐induced release of [3H]dopamine by carotid bodies isolated from animals allowed to recover for 8 days is not different from that of control animals. Our results suggest that modifications in the proportions of neurotransmitters, as well as changes in the stimulus‐secretion coupling machinery in chemoreceptor cells, contribute to the adaptative responses seen in the carotid body during high altitude acclimatization.
Cell Cycle Arrest of Proliferating Neuronal Cells by Serum Deprivation Can Result in Either Apoptosis or Differentiation
Authors: Howard M. Keith , Burke Lindsey C. , Mailhos Carolina , Pizzey Arnold , Gilbert Christopher S. , Durward Lawson W. , Collins Mary K. L. , Thomas N. Shaun B. , Latchman David S.
Published: December 2006

Abstract: Apoptotic cell death plays a critical role in the development of the nervous system. The death of mature nondividing neurons that fail to receive appropriate input from the target field has been extensively studied. However, the mechanisms mediating the extensive cell death occurring in areas of the developing brain where proliferating neuroblasts differentiate into mature nondividing neurons have not been analyzed. We show here that the cell cycle arrest of a proliferating cell of neuronal origin by removal of serum results in either apoptotic cell death or differentiation to a mature nondividing neuronal cell. The proportion of cells undergoing death or differentiation is influenced in opposite directions by treatment of the cells with cyclic AMP and retinoic acid. This suggests that following the withdrawal of signals stimulating neuroblast cell division, neuronal cells either can cease to suppress a constitutive suicide pathway and hence die by apoptosis or, alternatively, can differentiate into a mature neuronal cell. Regulation of the balance between apoptosis and neuronal differentiation could therefore play a critical role in controlling the numbers of mature neurons that form.
Regulation of Protein Kinase C Activity by Sensory Deprivation in the Olfactory and Visual Systems
Authors: Elkabes Stella , Cherry James A. , Schoups Aniek A. , Black Ira B.
Published: December 2006

Abstract: Environmental regulation of sensory function has provided an important model of plastic mechanisms mediating neural information processing. To define potential commonalities in information processing in different systems, we investigated molecular changes elicited by sensory deprivation in the developing rat olfactory and visual systems. Protein kinase C (PKC), an intracellular messenger implicated in synaptic plasticity and memory, was analyzed. Initial, developmental studies indicated that PKC activity in the soluble and particulate fractions of the olfactory bulb increased three‐ to fourfold from birth to 3 months of age. Unilateral olfactory deprivation prevented the developmental increase in both soluble and particulate PKC activities in the ipsilateral olfactory bulb and piriform cortex, the second‐order relay. Phorbol ester binding localized PKC to intrinsic neuronal populations and their dendrites in the control and deprived bulbs. Moreover, PKC was similarly lower in the visual cortex of dark‐reared rats than in light‐reared controls. The changes in PKC were region specific, as activity was unchanged by either treatment in the parietal cortex, a control area that does not process primary olfactory or visual information. Our results suggest that the important intracellular messenger, PKC, is similarly regulated in entirely different sensory systems by different environmental stimuli. Consequently, different sensory systems may use common molecular mechanisms to process information.
Hydrolysis of Inositol Trisphosphate by Purified Rat Brain Myelin
Authors: Larocca Jorge N. , Ledeen Robert W.
Published: December 2006

Abstract: Highly purified rat brain myelin was found to hydrolyze inositol 1,4,5‐trisphosphate to inositol 1.4‐bisphosphate, but subsequent hydrolysis of the latter, characteristic of whole brainstem, did not occur. Inositol 1,4,5‐trisphosphate 5‐phosphatase in myelin was ∼ 33% of the level in microsomes and 127% that of the cytosolic fraction from brainstem. The myelin and microsomal enzymes had similar properties, as follows: activation by saponin, requirement for Mg2+ and similar Kact (0.16 and 0.13 mM), Km (8.7 ± 2.5 and 7.0 ± 1.0 μM), and pH optima (6.6‐6.8). Vmax values were 11.2 ± 1.0 and 26.3 ± 2.0 nmol/mg/min for myelin and microsomes, respectively. A possible role for this enzyme in phosphoinositide‐mediated signal transduction within myelin and its subcompartments is discussed.
Effect of Chronic Estradiol and Progesterone Treatments of Ovariectomized Rats on Brain Dopamine Uptake Sites
Authors: Morissette M. , Paolo T. Di
Published: December 2006

Abstract: Dopamine released from brain nerve terminals is mainly removed from the synaptic cleft by an uptake mechanism. Despite their functional importance, modulation of the dopamine uptake sites is still not well known. Steroid hormones were shown to modulate brain dopamine transmission. The aim of this study was thus to investigate in ovariectomized rats the effects of 17β‐estradiol and progesterone treatments on brain dopamine uptake sites. Treatments consisted of 17β‐estradiol (10 μg/0.2 ml), progesterone (0.72 mg/0.2 ml). 17β‐estradiol + progesterone, or the vehicle (0.3% gelatin in saline solution) twice daily for 2 weeks. The steroid treatments left the affinity of [3H]GBR 12935 binding to striatal homogenates unchanged (ovariectomized rats, 0.823 ± 0.028 nM), whereas the density was increased by these steroids alone or in combination to a similar extent of 16‐23%. Chronic treatment of ovariectomized rats with 17β‐estradiol progesterone, or their combination increased to the same extent and uniformly [3H]‐GBR 12935 binding in the striatum as measured by autoradiography; the increase was similar in the substantia nigra pars compacta, whereas no steroid effect was observed in the nucleus accumbens and in the substantia nigra pars reticulata. In summary, chronic exposure to 17β‐estradiol and/ or progesterone increased dopamine uptake site density in the nigrostriatal dopaminergic system, whereas the nucleus accumbens and the substantia nigra pars reticulata were unaffected.
Rat Brain Glyceraldehyde‐3‐Phosphate Dehydrogenase Interacts with the Recombinant Cytoplasmic Domain of Alzheimer's β‐Amyloid Precursor Protein
Authors: Schulze Hermann , Schuler Angelika , Stüber Dietrich , Döbeli Heinz , Langen Hanno , Huber Gerda
Published: December 2006

Abstract: Abundant senile plaques are a histological hallmark in the brain of Alzheimer's disease patients. Such plaques consist of, among many other constituents, aggregated βA4 amyloid peptide. This peptide is derived from an amyloid precursor protein (APP) by irregular proteolytic processing and is considered to be involved in the development of Alzheimer's disease. To study possible interactions of brain proteins with 0A4 amyloid or other fragments of APP, βA4 amyloid and βA4 amyloid extended to the C‐terminus of APP were recombinantly produced as fusion proteins termed “Amy” and “AmyC,” respectively. Using Amy and AmyC affinity chromatography, a 35‐kDa protein from rat brain was isolated that bound tightly to AmyC but not to Amy, thus indicating an interaction of the protein with the C‐terminus of APP. This 35‐kDa protein was identified as the glycolytic enzyme gIyceraldehyde‐3‐phosphate dehydrogenase (GAPDH). Binding of GAPDH to AmyC but not to Amy was confirmed by gel filtration. Although AmyC slightly reduced the Vmax of GAPDH, the same reduction was observed in the presence of Amy. These findings suggest that the interaction of the cytoplasmic domain of APP with GAPDH is unlikely to influence directly the rate of glycolysis but may serve another function.
Long‐Term Treatment with Glucocorticoids Increases Synthesis and Stability of Junctional Acetylcholine Receptors on Innervated Cultured Human Muscle
Authors: Braun Serge , Askanas Valerie , Engel W. King , Ibrahim Emad N.
Published: December 2006

Abstract: We have studied the effect of long‐term treatment with hydrocortisone on the expression of acetylcholine receptors (AChRs) at the neuromuscular junctions of human muscle cultured in monolayer and innervated de novo by fetal rat spinal cord motoneurons. Hydrocortisone increased accumulation of junctional AChRs in a dose‐and time‐dependent fashion. This increase was due to both decreased degradation and increased synthesis of AChRs. Other glucocorticoids, dexamethasone and prednisolone, exerted similar effects. Our study demonstrates a novel action of glucocorticoids on human junctional AChRs.
Identification of the Cationic Amino Acid Transporter (System y+) of the Rat Blood‐Brain Barrier
Authors: Stoll James , Wadhwani Kishena C. , Smith Quentin R.
Published: December 2006

Abstract: Cationic amino acids are transported from blood into brain by a saturable carrier at the blood‐brain barrier (BBB). The transport properties of this carrier were examined in the rat using an in situ brain perfusion technique. Influx into brain via this system was found to be sodium independent and followed Michaelis‐Men‐ten kinetics with half‐saturation constants (Km) of 50–100 μM and maximal transport rates of 22–26 nmol/min/g for L‐lysine, L‐arginine, and L‐ornithine. The kinetic properties matched that of System y+, the sodium‐independent cationic amino acid transporter, the cDNA for which has been cloned from the mouse. To determine if the cloned receptor is expressed at the BBB, we assayed RNA from rat cerebral microvessels and choroid plexus for the presence of the cloned transporter mRNA by RNase protection. The mRNA was present in both cerebral microvessels and choroid plexus and was enriched in microvessels 38‐fold as compared with whole brain. The results indicate that System y+ is present at the BBB and that its mRNA is more densely expressed at cerebral microvessels than in whole brain.
Contractile activity of ATP and diadenosine tetraphosphate on urinary bladder in the rat: role of A1‐ and P2X‐purinoceptors and nitric oxide
Authors: Khattab M. M. , Al‐Hrasen M. N. , El‐Hadiyah T. M.
Published: December 2006

1 Both adenosine‐5′‐triphosphate (ATP) and diadenosine tetraphosphate (AP4A) produced a dose‐dependent contraction of the isolated rat urinary bladder rings. AP4A dose–response curve was to the left of that of ATP, and maximum response was greater than that produced by ATP.

2 8‐cyclopentyl‐1,3‐dipropylxanthine (DPCPX), the A1‐purinergic receptor blocker (0.01 mm) significantly inhibited the ATP‐ and AP4A‐induced contractions at the whole dose range. The inhibition was between 31–41%, and 15–25% for ATP and AP4A respectively.

3 Pyridoxal phosphate 6‐azophenyl‐2′,4′‐disulphonic acid (PPADS), the P2X‐purinoceptor antagonist (0.01 mm) potently inhibited the bladder contractions in response to ATP and AP4A by around 75–80%.

4 The nitric oxide (NO) precursorl‐arginine reduced the bladder contractile response to ATP by about 22–41% and that of AP4A to a lesser extent by around 20–32%.

5 The nitric oxide synthase inhibitor,NG‐nitro‐l‐arginine methyl ester (l‐NAME, 0.1 mm), did not produce any significant effect on ATP except for a weak inhibition of about 14% at the lowest dose of ATP. The contractions in response to AP4A were only slightly reduced byl‐NAME by about 20%.

6 In conclusion, the contractile response of the bladder to ATP and to the dinucleotide AP4A is mediated mainly through P2X‐purinoceptors and A1‐purinergic receptors. In the detrusor muscle, NO donation possesses an inhibitory effect on ATP‐mediated contractility more than that produced by the dinucleotide AP4A.
Potential antioxidant activity of celecoxib and amtolmetin guacyl: in vitro studies
Authors: Kirkova M. , Alexandova A. , Kesiova M. , Tsvetanova E. , Georgieva A. , Todorov S.
Published: December 2006

1 In vitro studies of the potential antioxidant activity of the selective cyclo‐oxygenase‐2 inhibitor celecoxib and the non‐steroid anti‐inflammatory drug amtolmetin guacyl (AMG) were carried out. The study included experiments on the ability of these drugs to affect some indices of the oxidative stress [lipid peroxidation (LP), activity of antioxidant enzymes, glutathione (GSH) level] in rat stomach and colon mucosa and in liver.

2 Celecoxib and AMG did not change the activity of the enzymes GSH‐peroxidase, oxidased glutathione (GSSG)‐reductase and glucose‐6‐phosphate‐dehydrogenase, as well as the GSH level in all tissue preparations. An increased superoxide dismutase (SOD) activity and a tendency to a decreased Fe/ascorbic acid‐induced LP in stomach and colon mucosa were found, but only in the presence of AMG.

3 In the liver, both celecoxib and AMG decreased spontaneous and Fe/ascorbic acid‐induced LP. SOD activity was enhanced only in the presence of AMG.

4 Experiments aimed at studying celecoxib and AMG in free oxygen radical‐generating systems were also carried out. AMG and tolmetin (the main metabolite of AMG) inhibited OH•‐provoked deoxyribose degradation in a Fenton system. Celecoxib had no effect on free radicals when tested in the same system.

5 In conclusion, the results of the present in vitro studies suggest that AMG and celecoxib possess antioxidant and metal‐chelating abilities, which might contribute to their beneficial effects.
Effect of short‐term outlet obstruction on rat bladder nerve density and contractility
Authors: Barendrecht M. M. , Chichester P. , Michel M. C. , Levin R. M.
Published: December 2006

1 The present study was designed to investigate the relationship between innervation density and contractile responses to field stimulation and exogenous agonists at early time points after induction of bladder outlet obstruction (BOO) in rats.

2 When compared with sham‐operated animals, 1, 3 and 7 days of BOO were associated with a 75%, 80% and 90% increase of bladder weight. Field stimulation caused a frequency‐dependent increase in force of contraction. The force of contraction was reduced at each frequency in BOO rats with the greatest decrease after 1 day and a gradual but incomplete recovery thereafter. In contrast, contractile responses to ATP, carbachol and KCl were markedly reduced after 1 day of BOO and fully recovered after 7 days. The neurofilament staining was not altered by 1 day of BOO, but gradually decreased with increasing duration of BOO reaching the lowest levels after 7 days.

3 We conclude that impaired cellular contractility seems to underlie the early reductions of field stimulation‐induced contraction, possibly reflecting surgical trauma of the tissue. However, at later time points a reduced nerve density, possibly reflecting a partial denervation, appears to be the main reason for impaired contractile response to field stimulation.
Automated metric calibration of colour digital cameras
Authors: Cronk Simon , Fraser Clive , Hanley Harry
Published: December 2006

Consumer‐grade digital cameras have become commonplace and with calibration there is significant potential for their use in photogrammetric applications. This paper describes a new method for automatic camera calibration, which is suited to colour digital cameras. Two innovations are central to the developed process. The first is exploitation of RGB colour attributes in the design of automatically detected and identified coded targets. The second is a new approach to initial value determination for relative orientation, which then supports fully automatic initial network exterior orientation and subsequent bundle adjustment with self‐calibration. Accuracy aspects are also touched upon and the impact of chromatic aberration is discussed. Finally, an example of the automatic calibration process, which is implemented in the iWitness system, is presented for the case of multiple zoom settings of a consumer‐grade digital camera.
Of Love and Politics: Reassessing Manuela Sáenz and Simón Bolívar, 1822–1830
Authors: Murray Pamela S.
Published: December 2006

This article critically examines the relationship between Simon Bolívar (aka the “Liberator”) and Manuela Sáenz, dispelling some of the romantic mist that long has surrounded it and that has obscured historical understanding of the famous couple. It also reassesses the relationship from Sáenz's perspective. It shows not only how Sáenz actively pursued an affair with her lover, but, how she integrated herself into his organization, becoming his informant and personal staff archivist and ultimately, one of his premier political allies. It, thus, seeks to shed light both on her remarkable career and on the nature of female citizenship in Spanish America in the early republican era.
Empire, Cultures and Identities in Nineteenth‐ and Twentieth‐Century Britain
Authors: Potter Simon J.
Published: December 2006

Over the last twenty years, historians have sought to gauge how the experience of establishing an empire overseas impacted upon the ways that British people thought about themselves and the world around them. As evidence has accumulated, so an increasingly heated historical debate about the exact significance of that source material has been generated. This article looks at where this controversy has taken us, assessing the range of evidence available and the different viewpoints adopted by various historians. It argues that, rather than present our conclusions in polarised terms, we need to acknowledge the wide range of imperial influences working on multiple British cultures and identities in the nineteenth and twentieth centuries. Moreover, given the problematic nature of the available evidence, we should acknowledge the difficulties inherent in any attempt to gauge the impact of those influences. Empire may well have helped to shape British cultures and identities, but it is not clear that it did so in a simple fashion, or that we have sufficient evidence to come to firm conclusions about its impact.
Efficacy of zinc treatment against iron‐induced toxicity in rat hepatoma cell line H4‐II‐E‐C3
Authors: Formigari A. , Santon A. , Irato P.
Published: December 2006

Objective: In this study, we have attempted to explore the possible protection afforded by Zn with regard to its antioxidant potential properties in the iron‐induced toxicity.

Methods: Rat hepatoma cell line H4‐II‐E‐C3 was treated with 150 μM ZnSO4, 200 μM FeSO4 or 150 μM ZnSO4+ 200 μM FeSO4 for 24 h. We studied the effect of metallothionein (MT), glutathione and metal (Fe and Zn) accumulation. We evaluated the levels of both MT‐1 and MT‐2 mRNAs, activities of antioxidant enzymes, and also determined the distribution of MT and cell death index.

Results: The cotreatment produced highest levels of MT. Fe concentration was significantly lower in the Zn–Fe‐treated cells compared with Fe‐treated cells. In both Zn treatments, the superoxide dismutase/glutathione peroxidase ratio was similar to control. The cell death index was lower in the Zn–Fe‐treated cells compared with Fe‐treated cells.

Conclusions: Zn may act as antioxidant by competitive inhibition of iron uptake by the divalent metal transporter and/or by MT induction.
Historic Anthropogenically Maintained Bear Grass Savannas of the Southeastern Olympic Peninsula
Authors: Peter David , Shebitz Daniela
Published: December 2006

This paper documents the existence and character of a little known fire‐maintained anthropogenic ecosystem in the southeastern Olympic Peninsula of Washington State, U.S.A. Due to cessation of anthropogenic burning, there is no longer an intact example of this ecosystem. We present evidence from Skokomish oral tradition, historical documents, floral composition, tree‐ring analysis, stand structure, and site potential to describe former savanna structure and function. We believe this system was a mosaic of prairies, savannas, and woodlands in a forest matrix maintained through repeated burning to provide culturally important plants and animals. The overstory was dominated by Douglas‐fir (Pseudotsuga menziesii). Bear grass (Xerophyllum tenax) likely was a dominant understory component of the savannas, woodlands, and prairie edges. These lands grew forests in the absence of anthropogenic burning. Wide spacing of older trees or stumps in former stands and rapid invasion by younger trees in the late 1800s and early 1900s suggest a sudden change in stand structure. Shade‐intolerant prairie species are still present where openings have been maintained but not in surrounding forests. Bark charcoal, fire scars, tree establishment patterns, and oral traditions point to use of fire to maintain this system. A common successional trajectory for all these lands leads to forested vegetation. These findings suggest that frequent application of prescribed burning would be necessary to restore this ecosystem.
Use of a Computer‐Based Reminder to Improve Sedative–Hypnotic Prescribing in Older Hospitalized Patients
Authors: Agostini Joseph V. , Zhang Ying , Inouye Sharon K.
Published: December 2006

OBJECTIVES: To develop a feasible, inexpensive, point‐of‐care computerized reminder to improve sedative‐hypnotic prescribing in hospitalized older people.

DESIGN: Pre‐postintervention with a computer‐based reminder.

SETTING: Academic medical center.

PARTICIPANTS: Hospitalized patients aged 65 and older.

INTERVENTION: Computer‐based reminder directing clinicians to prescribe a nonpharmacological sleep protocol, to minimize the potential for harm with diphenhydramine and diazepam use by choosing an alternative medication (trazodone or lorazepam), or both.

MEASUREMENTS: Frequency of prescription of four sedative‐hypnotic drugs (diphenhydramine, diazepam, lorazepam, and trazodone) during the 12 months before (n=12,356 patients) and after (n=12,153) the reminder was instituted.

RESULTS: Prescribing of sedative‐hypnotics decreased from 2,208 per 12,356 (18%) patients preintervention to 1,832 per 12,153 (15%) postintervention (odds ratio for the intervention=0.82, 95% confidence interval=0.76–0.87), an 18% risk reduction. Combined prescription rates for all four drugs fell consistently throughout the postintervention period. Diphenhydramine, diazepam, and lorazepam orders declined overall, with lorazepam prescriptions decreasing 39% during the intervention. Ninety‐five percent of patients were successfully directed to a safer sedative‐hypnotic drug or a nonpharmacological sleep protocol.

CONCLUSION: Using real‐time computer‐based reminders could lead to improved sedative‐hypnotic prescribing for older persons in acute care. This study highlights the potential to address patient safety concerns, and the quality of medication prescribing in particular, in vulnerable hospitalized patients.
What Level of Alcohol Consumption Is Hazardous for Older People? Functioning and Mortality in U.S. and English National Cohorts
Authors: Lang Iain , Guralnik Jack , Wallace Robert B. , Melzer David
Published: December 2006

OBJECTIVES: To estimate disability plus mortality risks in older people according to level of alcohol intake.

DESIGN: Two population‐based cohort studies.

SETTING: The Health and Retirement Study (United States) and the English Longitudinal Study of Aging (England).

PARTICIPANTS: Thirteen thousand three hundred thirty‐three individuals aged 65 and older followed for 4 to 5 years.

MEASUREMENTS: Difficulties with activities of daily living (ADLs), instrumental activities of daily living (IADLs), poor cognitive function, and mortality.

RESULTS: One‐tenth (10.8%) of U.S. men, 28.6% of English men, 2.9% of U.S. women, and 10.3% of English women drank more than the U.S. National Institute on Alcohol Abuse and Alcoholism recommended limit for people aged 65 and older. Odds ratios (ORs) of disability, or disability plus mortality, in subjects drinking an average of more than one to two drinks per day were similar to ORs in subjects drinking an average of more than none to one drink per day. For example, those drinking more than one to two drinks per day at baseline had an OR of 1.0 (95% confidence interval (CI)=0.8–1.2) for ADL problems, 0.7 (95% CI=0.6–1.0) for IADL problems, and 0.8 (95% CI=0.6–1.1) for poor cognitive function. Findings were robust across alternative models. The shape of the relationship between alcohol consumption and risk of disability was similar in men and women.

CONCLUSION: Functioning and mortality outcomes in older people with alcohol intakes above U.S. recommended levels for the old but within recommendations for younger adults are not poor. More empirical evidence of net benefit is needed to support screening and intervention efforts in community‐living older people with no specific contraindications who drink more than one to two drinks per day.