bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of Protein Phosphorylation in Microvessels Isolated from Rat Brain: Modulation by Second Messengers
Authors: Oláh Z. , Novak R. , Lengyel I. , Dux E. , Joó F. 
Published: October 2006

AbstractThe role of second messengers in the regulation of protein phosphorylation was studied in microvessels isolated from rat cerebral cortex. The phosphoproteins were separated by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis, and the kinetics of 32P incorporation into specific protein substrates were evaluated by computer‐aided x‐ray film densitometry. With the use of this method, Ca2+‐calmodulin (CAM)‐, Ca2+/phospholipid (PK C)‐, cyclic GMP (cGMP)‐, and cyclic AMP (cAMP)‐dependent protein kinases were detected. CAM‐dependent protein ki‐nase proved to be the major phosphorylating enzyme in the microvascular fraction of the rat cerebral cortex; the activity of cGMP‐dependent protein kinase was much higher than that of the cAMP‐dependent one. Autophosphoryla‐tion of both the α‐ and β‐subunits of CAM‐dependent protein kinase and the proteolytic fragment of the PK C enzyme was also detected. The kinetics of phosphorylation of the individual polypeptides indicate the presence in the cerebral endothelium of phosphoprotein phosphatases. The phosphorylation of proteins in the cerebral capillaries was more or less reversible; the addition of second messengers initiated a very rapid increase in 32P incorporation, followed by a slow decrease. Because the intracellular signal transducers like Ca2+ and cyclic nucleotides are frequently regulated by different vasoactive substances in the endothe‐lial cells, the modified phosphorylation evoked by these second messengers may be related in vivo to certain changes in the transport processes of the blood‐brain barrier.
γ‐Aminobutyric Acid Agonist‐Induced Alterations in the Ultrastructure of Cultured Cerebellar Granule Cells Is Restricted to Early Development
Authors: Hansen Gert H. , Belhage Bo , Schousboe Arne , Meier Eddi 
Published: October 2006

AbstractThe effect of 4,5,6,7‐tetrahydroisoxazolo[5,4‐c]‐pyridin‐3‐ol (THIP) on the ultrastructural composition of cultured cerebellar granule cells was investigated during development by quantitative electron microscopy (morphometric analysis). Granule cells were exposed to THIP (150 μM) for 6 h after 7 and 14 days, respectively, in culture. THIP treatment of 7‐day‐old cultures led to a statistically significant increase in the cytoplasmic density of rough endoplasmic reticulum, Golgi apparatus, vesicles, and coated vesicles, whereas no significant increase in the cytoplasmic density of these organelles was observed in 14‐day‐old cultures exposed to THIP for 6 h. These findings show that the effect of THIP on the ultrastructural composition of cultured cerebellar granule cells is restricted to early development.
Slow Penetration of Thyrotropin‐Releasing Hormone Across the Blood‐Brain Barrier of an In Situ Perfused Guinea Pig Brain
Authors: Zloković Berislav V. , Lipovac Milo N. , Begley David J. , Davson Hugh , Rakić Ljubiša 
Published: October 2006

AbstractTransport of 3H‐labelled thyrotropin‐releasing hormone (TRH) across the blood‐brain barrier was studied in the ipsilateral perfused in situ guinea pig forebrain. The unidirectional transfer constant (Kin) calculated from the multiple time brain uptake analysis ranged from 1.14 × 10‐−3 to 1.22 × 10‐−3 ml min−1 g−1, in the parietal cortex, caudate nucleus, and hippocampus. Regional Kin values for [3H]TRH were significantly reduced by 43–48% in the presence of an aminopeptidase and amidase inhibitor, 2 mM bacitracin, suggesting an enzymatic degradation of tripeptide during interaction with the blood‐brain barrier. In the presence of unlabelled 1 mM TRH and 2 mM bacitracin together, a reduction of [3H]TRH regional Kin values similar to that obtained with 2 mM bacitracin alone was obtained. l‐Prolinamide, the N‐terminal residue of tripeptide, at a 10 mM level had no effect on the kinetics of entry of [3H]TRH into the brain. The data indicate an absence of a specific saturable transport mechanism for TRH presented to the luminal side of the blood‐brain barrier. It is concluded that intact TRH molecule may slowly penetrate the blood‐brain barrier, the rate of transfer being some three times higher than that of d‐mannitol.
Glutamate Transport and Not Glutamate Receptor Binding Is Stimulated by Gangliosides in a Ca2+‐Dependent Manner in Rat Brain Synaptic Plasma Membranes
Authors: Hollmann Michael , Seifert Wilfried 
Published: October 2006

AbstractCrude as well as purified synaptic plasma membrane (SPM) preparations were analyzed for the influence of the ganglioside galactosyl‐N‐acetylgalactosalminyl‐(N‐acetyl‐neuraminyl)‐galactosylglucosyl ceramide (GMl) on high‐affinity binding of L‐[3H]glutamate. Assayed in two different buffer systems, SPM consistently exhibited increased (40–50%) binding upon incubation with GM1 plus Ca2+, as compared to controls without GM1. Incorporation experiments with 3H‐labeled GM1 proved trypsin‐stable insertion of GM1 into SPM, with a maximum incorporation pf four times the endogenous amount (35 nmol/mg of protein). The observed increase in glutamate binding was not due to a change in the affinity of the binding sites, but to a change in the number of binding sites, and it was absolutely dependent on the presence of Ca2+. A pharmacological profile of the GM1/Ca2+‐stimulated glutamate binding is presented. The original classification of the stimulatory effect as an effect on glutamate receptor binding had to be revised to take into account the observed temperature sensitivity of the ganglioside effect, its sensitivity to high osmolarity and to ultrasonication, and the lack of binding stimulation after detergent treatment of membranes or after receptor solubilization. Vesicular space measured in both SPM preparations was found to be around 7 μl/mg of protein, in ganglioside‐treated as well as in control membranes. From the data, it is concluded that a special. Na+‐ and C1‐independent form of glutamate transport into resealed membrane vesicles is stimulated by gangliosides in the presence of Ca2+.
Temporal Profile of Levels of Monoamines and Their Metabolites in Striata of Rats Implanted with Dialysis Tubes
Authors: Reiriz J. , Mena M.A. , Bazán E. , Muradás V. , Lerma J. , Delgado J. M R. , De Yébenes J. G. 
Published: October 2006

AbstractWe have measured the levels of monoamines and their metabolites in rat striata implanted with a dialysis tube, in contralateral nonimplanted striata, and in diialysates obtained from the dialysis tube. The perfusion was done with Ringer solution. The animals were perfused either for a continuous period of 7 h at 1 day after implantation or for periods of 2 h on days 1, 4, and 7 after implantation] In animals perfused for 7 h, levels of monoamine metabolites in dialy‐sates remained stable for the first 4 h of perfusion, but a reduction was observed during the last 3 h. In Animals perfused for 2 h on days 1, 4, and 7 after implantation, we observed a progressive reduction in levels of metabolites in di‐alysates with respect to the first day of perfusion The levels of dopamine and its metabolites in the striata in which a dialysis cannula had been implanted showed a progressive reduction during the period postimplantation comparable to that observed in dialysates. The levels of 3‐methoxytyramine, 3,4‐dihydroxyphenylacetic acid, and homovanillic acid were elevated 24 h after implantation in the implanted striata with respect to the contralateral nonimplanted striata, but 7 days after implantation, the levels of dopamine were decreased in the implanted striata, and tne levels of metabolites were unchanged.
Direct Transfer into Nitrocellulose and Quantitative Radioautographic Anatomical Determination of Brain Tyrosine Hydroxylase Protein Concentration
Authors: Weissmann Dinah , Labatut René , Richard Françoise , Rousset Colette , Pujol Jean‐François 
Published: October 2006

AbstractAn improved quantitative immunochemical determination of brain tyrosine hydroxylase (TH) concentra‐tions was designed using direct transfer into nitrocellulose from 20‐μm thick brain sections, followed by immunodetection and quantitative radioautography in three reference brain structures (locus ceruleus, substantia nigra, and ventral tegmental area). Results obtained by this methodology were similar to those obtained after extraction and Western blotting of the TH protein in control and reserpine‐treated animals. Moreover, this methodology allows the combination of high sensitivity and high anatomical resolution in the study of the distribution of pharmacological effects. The locus ceruleus exhibited a significant posteroanterior distribution of TH protein concentration in control and reserpine‐treated animals.
Selective Inhibition of Nerve Growth Factor‐Stimulated Protein Kinases by K‐252a and 5′‐S‐Methyladenosine in PC12 Cells
Authors: Smith Deanna S. , King Carolyn S. , Pearson Eric , Gittinger Cynthia K. , Landreth Gary E. 
Published: October 2006

AbstractK‐252a, a protein kinase inhibitor isolated from the culture broth of Nocardiopsis sp., inhibits the nerve growth factor (NGF)‐stimulated phosphorylation of microtubule‐associated protein 2 (MAP2) and Kemptide (synthetic Leu‐Arg‐Arg‐Ala‐Ser‐Leu‐Gly) by blocking the activation of two independent kinases in PC 12 cells: MAP2/pp250 kinase and Kemptide kinase. The NGF‐stimulated activation of these kinases is inhibited in a dose‐dependent manner following treatment of the cells with K‐252a. Although these kinases also are activated by epidermal growth factoi (EGF) and 12‐O‐tetradecanoyl‐phorbol 13‐acetate, K‐252a has no inhibitory effect when these agents are used. Half‐maximal inhibition of the activation of both kinases was observed at 10–30 nM K‐252a. K‐252a was shown to directly inhibit the activity of MAP2/pp250 kinase and Kemptide kinase when added tc the phosphorylation reaction mixture in vitro; however, half‐maximal inhibition under these conditions was observed at ±50 nM K‐252a. These data suggest that K‐252a exerts its effects at a step early in the cascade of events following NGF binding. The effects of K‐252a are similar to those reported for 5′‐S‐methyladenosine (MTA) and other methyltransferase inhibitors. Treatment of PC12 cells with MTA inhibited NGF‐, but not EGF‐mediated activation of MAP2/pp250‐kinase (Ki± 500 μM). MTA, when added to the phosphorylation reaction mixture in vitro, directly inhibited kinase activity (Ki= 50 μM), suggesting that the effects of MTA may be the result of its action on protein kinases rather than methyltransferases.
Catecholamine‐Sensitive Adenylate Cyclase in the White Perch (Roccus americanus) Retina: Evidence for β‐Adrenergic and Dopamine Receptors Linked to Adenylate Cyclase
Authors: O'Connor Patricia , Kropf Rita B. , Dowling John E. 
Published: October 2006

AbstractWe have examined the catecholamine‐sensitive adenylate cyclase in the retina of the white perch (Roccus americanus). Both dopamine and the β‐adrenergic agonist isoproterenol stimulate cyclic AMP accumulation in this retina, but serotonin, an indoleamine, and phenylephrine, an α‐adrenergic agonist, had no effect. The stimulation of adenylate cyclase by isoproterenol is more potent and effective than that of dopamine. The effects of dopamine and isoproterenol are mediated via independent dopamine and β‐adrenergic receptors. Haloperidol, a dopamine antagonist, blocks the stimulatory effect of dopamine but not of isoproterenol. Conversely, propranolol, a β‐adrenergic antagonist, blocks the stimulatory effect of isoproterenol but not of dopamine. The effects of dopamine and isoproterenol are not additive. In fractions of purified horizontal cells we found evidence for dopamine receptors linked to adenylate cyclase but did not find evidence for the presence of cyclase coupled β‐adrenergic receptors. The cellular location of the β‐adren‐ergic receptors is unknown. Our findings demonstrate the existence of both β‐adrenergic and dopamine receptors coupled to adenylate cyclase in the white perch retina. However, we did not find either epinephrine or norepinephrine, endogenous ligands of the β‐receptor, to be present in retinal extracts subjected to HPLC.
Thromboxane and Prostacyclin Levels in Fetal Rabbit Brain and Placenta After Intrauterine Partial Ischemic Episodes
Authors: Goldin Ehud , Harel Shaul , Tomer Abraham , Yavin Ephraim 
Published: October 2006

Abstract:The appearance of arachidonic acid (AA) oxidation products in fetal rabbit brain and placenta under normal or partial short‐term ischemic episodes induced by placental blood vessel restriction was examined. Intracerebral administration of [3H]AA into close‐to‐term rabbit fetuses gave rise to radioactively labeled prostaglandin (PG) E2, thromboxane B2, and 6‐keto‐PGF1 metabolites as detected by HPLC analysis. A significant increase of 20–30% of [3H]AA precursor into eicosanoids was detected in brain of fetuses after 2‐h restriction. The thromboxane B2 and 6‐keto‐PGF1 levels were determined by radioimmunoassay technique over a period of 48 h following ischemic episodes. Thromboxane B2 content in affected animals was higher by five‐ and twofold at 3 h over control fetal brain and placental tissue values, respectively, and remained significantly high for 24 h. 6‐Keto‐PGF1 levels reached a peak value that was greater by 2.5‐ and 1.5‐fold at 6 h for the ischemic brain and placental tissue, respectively, compared with control fetuses. PGE2 levels were less affected, attaining a maximum of 1.9‐ and 1.1‐fold in brain and placenta correspondingly. The thromboxane/prostacyclin ratio reached a maximum in the brain after ∼3 h, while that in the placenta continued to rise even after 20 h. Persisting high levels of thromboxane are indicative of cerebral vasoconstriction and may suggest possible damaging effects.
Transient Hypoxia Alters Striatal Catecholamine Metabolism in Immature Brain: An In Vivo Microdialysis Study
Authors: Gordon Kevin , Statman Daniel , Johnston Michael V. , Robinson Terry E. , Becker Jill B. , Silverstein Faye S. 
Published: October 2006

Abstract:Microdialysis probes were inserted bilaterally into the striatum of 7‐day‐old rat pups (n = 30) to examine extracellular fluid levels of dopamine, its metabolites 3,4‐dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), and the serotonin metabolite 5‐hydroxyindoleacetic acid (5‐HIAA). The dialysis samples were assayed by HPLC with electrochemical detection. Baseline levels, measured after a 2‐h stabilization period, were as follows: dopamine, not detected; DOPAC, 617 ± 33 fmol/min; HVA, 974 ± 42 fmol/min; and 5‐HIAA, 276 ± 15 fmol/min. After a 40‐min baseline sampling period, 12 animals were exposed to 8% oxygen for 120 min. Hypoxia produced marked reductions in the striatal extracellular fluid levels of both dopamine metabolites (p < 0.001 by analysis of variance) and a more gradual and less prominent reduction in 5‐HIAA levels (p < 0.02 by analysis of variance), compared with controls (n = 12) sampled in room air. In the first hour after hypoxia, DOPAC and HVA levels rose quickly, whereas 5‐HIAA levels remained suppressed. The magnitude of depolarization‐evoked release of dopamine (elicited by infusion of potassium or veratrine through the microdialysis probes for 20 min) was evaluated in control and hypoxic animals. Depolarization‐evoked dopamine efflux was considerably higher in hypoxic pups than in controls: hypoxic (n = 7), 257 ± 32 fmol/min; control (n = 12), 75 ± 14 fmol/min (p < 0.001 by analysis of variance). These data demonstrate that a brief exposure to moderate hypoxia markedly disrupts striatal catecholamine metabolism in the immature rodent brain.
Rat Brain Glutamic Acid Decarboxylase Sequence Deduced from a Cloned cDNA
Authors: Julien Jean‐François , Samama Philippe , Mallet Jacques 
Published: October 2006

Abstract:A cDNA clone complementary to the rat brain glutamic acid decarboxylase mRNA was isolated from a rat brain cDNA expression library using an antibody specific to the enzyme. The cDNA insert has been shown to direct the synthesis of an active protein in Escherichia coli. In this study, the nucleotide sequence of this clone, which includes the complete coding region, is presented. The predicted protein is 593 amino acids in length. The first 557 residues display a 95% identity when compared with the corresponding cat sequence. However, the deduced amino acid sequence of the carboxy‐terminal end of the rat protein, downstream of residue 557, is totally different from the cat, whereas it agrees with a published partial peptidic sequence of the rat protein.
A New Enzymatic Cycling Technique for Glutamate Determination in Brain Microdialysates
Authors: Mitani Akira , Kubo Hirohiko , Iga Kouzo , Imon Hitoshi , Kadoya Fumito , Kataoka Kiyoshi 
Published: October 2006

Abstract:A quantitative analysis of glutamate in brain dialysate was made by using an enzymatic cycling technique. This method made it possible to measure the concentration of glutamate in dialysate collected at 30‐s intervals. Dialysates were collected from Mongolian gerbil hippocampus before, during, and after two 90‐s ischemic insults at an interval of 5 min. An extracellular increase in levels of glutamate was already observed in samples collected during a 30–60 s period after the onset of each ischemia, and the levels of glutamate were maximal at the end of each period of ischemia (approximately a fourfold increase). The increased levels of glutamate rapidly returned almost to preischemic levels by 30 s of recirculation. This method will provide more precise information about temporal changes in the extracellular glutamate concentration in the brain during ischemia.
Phaco‐trabeculotomy combined with deep sclerectomy, a new technique in combined cataract and glaucoma surgery: complication profile
Authors: Lüke Christoph , Dietlein Thomas S. , Lüke Matthias , Konen Walter , Krieglstein Günter K. 
Published: October 2006

Abstract.Purpose:  Combined phacoemulsification, intraocular lens implantation and trabeculectomy (PTE) is currently the standard procedure for most ophthalmic surgeons for treating uncontrolled open‐angle glaucoma and cataract at the same time. The present pilot study was designed to prospectively evaluate outcomes in glaucoma patients who underwent a new technique of phaco‐trabeculotomy plus deep sclerectomy, with particular attention to the complication profile.Methods:  A consecutive series of 15 patients with uncontrolled open‐angle glaucoma and cataract underwent combined glaucoma and cataract surgery. The procedure started as a two‐site approach with phacoemulsification and intraocular lens (IOL) implantation through a temporal incision in clear cornea. Trabeculotomy and deep sclerectomy were performed in the superior quadrant. Postoperative examinations were performed daily for 1 week. Follow‐up visits were carried out at 1, 3, 6 and 12 months after surgery.Results:  At 1 day post‐surgery, mean intraocular pressure (IOP) was significantly reduced to 14.2 mmHg (SD 4.4). At 12 months post‐surgery, the complete success rate, defined as IOP < 22 mmHg without medication, was 60%. Qualified success was achieved in 93.3% of patients. At 12 months post‐surgery, the mean number of antiglaucoma medications had fallen to 0.4 (SD 0.6) (p < 0.001). Visual acuity improved by a mean value of 1.6 lines (SD 2.4) over baseline (p = 0.021). Specific complications such as choroidal deroofing, inadvertent perforation of the trabeculo−descemetic membrane, and non‐identification of Schlemm's canal were seen among the patients in our trial. The incidence of complications due to overfiltration was low. A relatively high incidence of hyphaemas (53%) was noted in this series. All the hyphaemas were trivial and resolved quickly. No severe complications, such as bleb infection, endophthalmitis or choroidal haemorrhage were seen in this series.Conclusions:  Phaco‐trabeculotomy plus deep sclerectomy offered significant IOP reduction and a success rate that may be comparable with that of the current standard, PTE. Intra‐ and postoperative complications specific to deep sclerectomy and trabeculotomy were seen in our series, although the overall rate of postoperative complications proved low. Prospective comparative trials are needed to assess which of PTE and phaco‐trabeculotomy plus deep sclerectomy is more successful.
Leucine 7−proline 7 polymorphism in the signal peptide of neuropeptide Y is not a risk factor for exudative age‐related macular degeneration
Authors: Kaarniranta Kai , Holopainen Juha M. , Karvonen Matti K. , Koulu Markku , Kallio Jaana , Pesonen Ullamari , Teräsvirta Markku , Uusitalo Hannu , Immonen Ilkka 
Published: October 2006

Abstract.Purpose:  Because of the regulatory role of neuropeptide Y (NPY) in angiogenesis, we set out to determine the presence of the leucine 7−proline 7 (Leu7Pro) polymorphism in exudative age‐related macular degeneration (AMD) patients and to analyse its implications.Methods:  Genotype analysis of the Leu7Pro polymorphism in the signal peptide region of the human prepro‐NPY was performed in blood samples from exudative AMD patients (n = 240) and control subjects (n = 79).Results:  In all, 11% of exudative AMD patients and 14% of control subjects exhibited the NPY signal peptide Leu7Pro polymorphism. There were no statistically significant differences in Leu7Pro polymorphism frequency between the exudative AMD and control cases, as analysed by Fisher's exact two‐sided test.Conclusions:  Leu7Pro polymorphism in the signal peptide region of the human prepro‐NPY is not a risk factor for exudative AMD.
Survival of the Mammary Tumor Milk Agents of Mice
Authors: Bittner John J. , Evans Charles A. , Green Robert G. 
Published: October 2006

The mammary tumor milk agent has been recovered from a transplanted mammary carcinoma that was carried for 10 passages in mice that did not themselves originally have the agent. It is possible that the agent, carried in the transplanted mammary tumor cells, may be responsible for the genetic mutations which have been detected in transplantable tumors.
Preliminary results show that the agent can be recovered from the yolk sac of chick embryos 12 days after the injection into eggs of either tumor suspensions or cell-free filtrates of tissues containing the active agent.
Strontium-90 in Man
Authors: Kulp J. Laurence , Eckelmann Walter R. , Schulert Arthur R. 
Published: October 2006

The world-wide average strontium-90 content of man was about 0.12 micromicrocurie per gram of calcium (1/10,000 of the maximum permissible concentration) in the fall of 1955. A few values as high as 10 times the average have been obtained.
This value is in accord with the predicted value based on fallout measurements and fractionation through the soil-plant-milk-human chain.
With the present burden of strontium-90, this average level should rise to 1 to 2 micromicrocuries of strontium-90 per gram of calcium by 1970.