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1.
Clin Oncol (R Coll Radiol) ; 31(2): 115-123, 2019 02.
Article in English | MEDLINE | ID: mdl-30502094

ABSTRACT

AIMS: To examine the influence of pre-existing psychiatric disorder on the choice of treatment in patients with gynaecological cancer. MATERIALS AND METHODS: The analyses were based on all patients who underwent surgical treatment for endometrial, ovarian or cervical cancer who were registered in the Danish Gynecological Cancer Database in the years 2007-2014 (3059 patients with ovarian cancer, 5100 patients with endometrial cancer and 1150 with cervical cancer). Logistic regression model and Cox regression model, adjusted for relevant confounders, were used to estimate the effect of pre-existing psychiatric disorder on the course of cancer treatment. Our outcomes were (i) presurgical oncological treatment, (ii) macroradical surgery for patients with ovarian cancer, (iii) radiation/chemotherapy within 30 days and 100 days after surgery and (iv) time from surgery to first oncological treatment. RESULTS: In the group of patients with ovarian cancer, more patients with a psychiatric disorder received macroradical surgery versus patients without a psychiatric disorder, corresponding to an adjusted odds ratio of 1.24 (95% confidence interval 0.62-2.41) and the chance for having oncological treatment within 100 days was odds ratio = 1.26 (95% confidence interval 0.77-2.10). As for patients with endometrial cancer, all outcome estimates were close to unity. The adjusted odds ratio for oncological treatment within 30 days after surgery in patients with cervical cancer with a history of psychiatric disorder was 0.20 (95% confidence interval 0.03-1.54). CONCLUSIONS: We did not find any significant differences in the treatment of ovarian and endometrial cancer in patients with pre-existing psychiatric diagnoses. When it comes to oncological treatment, we suggest that increased attention should be paid to patients with cervical cancer having a pre-existing psychiatric diagnosis.


Subject(s)
Genital Neoplasms, Female/psychology , Mental Disorders/psychology , Cohort Studies , Female , Humans , Middle Aged
2.
J Bone Joint Surg Am ; 83-A Suppl 1(Pt 2): S136-45, 2001.
Article in English | MEDLINE | ID: mdl-11314791

ABSTRACT

BACKGROUND: The surgical placement of dental implants is governed primarily by the prosthetic design and secondarily by the morphology and quality of the alveolar bone. Implant placement may be difficult, if at all possible, due to alveolar ridge aberrations. In consequence, prosthetically dictated dental implant positioning often entails augmentation of the alveolar ridge and adjacent structures. The objective of this review is to discuss recent observations of the biologic potential, the clinical relevance, and the perspectives of the application of recombinant human bone morphogenetic protein-2 (rhBMP-2) technology for alveolar bone augmentation and dental implant fixation. METHODS: Our studies use discriminating, critical-size, supraalveolar defects in dogs to evaluate the biologic potential of the rhBMP-2 technology. We also use clinical modeling, including peri-implantitis and alveolar ridge defects and the maxillary sinus in preparation for clinical indications, in dogs and inhuman primates. RESULTS: The results suggest that rhBMP-2 has substantial potential to augment alveolar bone and support dental implant fixation and functional loading. CONCLUSION AND CLINICAL RELEVANCE: Inclusion of rhBMP-2 for alveolar bone augmentation and dental implant fixation will not only enhance the predictability of the existing clinical protocol but will also allow new approaches to these procedures.


Subject(s)
Alveolar Ridge Augmentation , Bone Morphogenetic Proteins/administration & dosage , Dental Implantation, Endosseous , Transforming Growth Factor beta , Alveolar Bone Loss/therapy , Animals , Bone Morphogenetic Protein 2 , Drug Carriers , Recombinant Proteins/administration & dosage
3.
J Periodontol ; 71(3): 488-96, 2000 Mar.
Article in English | MEDLINE | ID: mdl-10776939

ABSTRACT

BACKGROUND: Recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge (ACS) carrier induces bone for reconstruction of skeletal defects. The rhBMP-2/ACS implant is prepared by administering a rhBMP-2 solution to dry ACS. Once prepared, rhBMP-2/ACS forms a moldable, cohesive, and adhesive implant. However, rhBMP-2/ACS does not have sufficient structural strength to withstand soft tissue compression at specific anatomic sites. To more fully understand the mechanisms that affect bone induction by rhBMP-2/ACS in the presence of soft tissue compression, it would be useful to have a preclinical model that appropriately simulates such circumstances in patients. This pilot study evaluated one such potential model. METHODS: Bilateral, Class III alveolar defects were surgically produced in 4 adult mongrel dogs following extraction of the mandibular fourth premolars and reduction of the alveolar ridge. After an 8-week healing interval, mucoperiosteal flaps were elevated and rhBMP-2/ACS or rhBMP-2/ACS combined with hydroxyapatite (HA) was implanted into contralateral defects. The animals were euthanized at 12 weeks post-augmentation and block biopsies processed for histologic evaluation. RESULTS: Limited augmentation followed implantation of rhBMP-2/ACS (0.7 +/- 0.6 mm). In contrast, sites receiving rhBMP-2/ACS/HA exhibited clinically relevant ridge augmentation (5.5 +/- 1.6 mm). Defects implanted with rhBMP-2/ACS exhibited dense trabeculation within the corpus of the reduced alveolar process. The cortices appeared intact without evidence of expansion into the defect area. Three defects receiving rhBMP-2/ACS/HA exhibited sparse bone trabeculae amidst HA particles, fibrovascular tissue, and marrow. Commonly, the HA particles were encapsulated by fibrous tissue. Some particles were observed in contact with bone. CONCLUSIONS: The results suggests that rhBMP-2/ACS has limited effect alone in this augmentation model of Class III alveolar ridge defects. Inclusion of HA into the rhBMP-2 construct results in clinically relevant augmentation, however, the quality of bone is compromised.


Subject(s)
Absorbable Implants , Alveolar Ridge Augmentation/methods , Bone Morphogenetic Proteins/therapeutic use , Collagen , Mandible/surgery , Transforming Growth Factor beta/therapeutic use , Alveolar Process/pathology , Alveolectomy , Animals , Bicuspid/surgery , Biocompatible Materials/therapeutic use , Biopsy , Bone Morphogenetic Protein 2 , Bone Morphogenetic Proteins/administration & dosage , Bone Regeneration/drug effects , Bone Substitutes/therapeutic use , Disease Models, Animal , Dogs , Drug Carriers , Durapatite/therapeutic use , Humans , Mouth Mucosa/pathology , Pilot Projects , Pressure , Recombinant Proteins , Surgical Flaps , Tooth Extraction , Transforming Growth Factor beta/administration & dosage , Wound Healing
4.
J Gen Physiol ; 112(1): 71-84, 1998 Jul.
Article in English | MEDLINE | ID: mdl-9649584

ABSTRACT

Protein kinase C inhibits inactivation gating of Kv3.4 K+ channels, and at least two NH2-terminal serines (S15 and S21) appeared involved in this interaction (. Neuron. 13:1403-1412). Here we have investigated the molecular mechanism of this regulatory process. Site-directed mutagenesis (serine --> alanine) revealed two additional sites at S8 and S9. The mutation S9A inhibited the action of PKC by approximately 85%, whereas S8A, S15A, and S21A exhibited smaller reductions (41, 35, and 50%, respectively). In spite of the relatively large effects of individual S --> A mutations, simultaneous mutation of the four sites was necessary to completely abolish inhibition of inactivation by PKC. Accordingly, a peptide corresponding to the inactivation domain of Kv3.4 was phosphorylated by specific PKC isoforms, but the mutant peptide (S[8,9,15,21]A) was not. Substitutions of negatively charged aspartate (D) for serine at positions 8, 9, 15, and 21 closely mimicked the effect of phosphorylation on channel inactivation. S --> D mutations slowed the rate of inactivation and accelerated the rate of recovery from inactivation. Thus, the negative charge of the phosphoserines is an important incentive to inhibit inactivation. Consistent with this interpretation, the effects of S8D and S8E (E = Glu) were very similar, yet S8N (N = Asn) had little effect on the onset of inactivation but accelerated the recovery from inactivation. Interestingly, the effects of single S --> D mutations were unequal and the effects of combined mutations were greater than expected assuming a simple additive effect of the free energies that the single mutations contribute to impair inactivation. These observations demonstrate that the inactivation particle of Kv3.4 does not behave as a point charge and suggest that the NH2-terminal phosphoserines interact in a cooperative manner to disrupt inactivation. Inspection of the tertiary structure of the inactivation domain of Kv3.4 revealed the topography of the phosphorylation sites and possible interactions that can explain the action of PKC on inactivation gating.


Subject(s)
Ion Channel Gating/physiology , Potassium Channels/genetics , Potassium Channels/metabolism , Protein Kinase C/metabolism , Amino Acid Sequence , Amino Acid Substitution , Animals , Aspartic Acid , Molecular Sequence Data , Mutagenesis, Site-Directed , Oocytes/physiology , Patch-Clamp Techniques , Phosphorylation , Serine/metabolism , Structure-Activity Relationship , Xenopus
6.
Mol Pharmacol ; 36(5): 689-98, 1989 Nov.
Article in English | MEDLINE | ID: mdl-2586487

ABSTRACT

Venom from the green mamba, Dendroaspis angusticeps, contains four polypeptides termed dendrotoxins (DaTXs) that block brain Ca-independent voltage-gated K channels. We compared the binding to rat brain receptors of two of these DTXs, alpha-DaTX and beta-DaTX, which preferentially block inactivating and noninactivating K channels, respectively. 125I-alpha-DaTX and 125I-beta-DaTX bind to single classes of receptor sites on synaptic membranes (KD = 0.7 and 36 nM for alpha-DaTX and beta-DaTX, respectively), with pH optima of about 6.5. The binding of both iodinated toxins was optimal in solutions containing 150 mM NaCl and decreased as Na was replaced with other alkali metal ions; the rank order for support of toxin binding was Na greater than K greater than Li greater than Rb. Cs (IC50 = 5-6 mM) prevented toxin binding, as did the divalent cations Ba and Ca (IC50 = 4-6 and 9-13 mM, respectively). The inhibition of 125I-alpha-DaTX binding by Cs and Ba was noncompetitive. The displacement of 125I-alpha-DaTX and 125I-beta-DaTX binding by the four unlabeled DaTXs was similar; the relative potency was alpha-DaTX greater than beta-DaTX greater than gamma-DaTX. The displacement curve for delta-DaTX did not parallel the others. When cross-linked with dimethylsuberimidate, both iodinated toxins covalently labeled membrane polypeptides of similar molecular weight (Mr = 65,000). The alpha-DaTX and beta-DaTX receptors were solubilized from rat synaptic membranes. Toxin binding to the soluble from rat synaptic membranes. Toxin binding to the soluble receptors was preserved in the presence of K and lecithin and decreased as K was replaced with Rb greater than Cs greater than Li greater than Na. The affinity of 125I-alpha-DaTX for the solubilized receptor was decreased 10-fold (KD = 7 nM); the affinity of 125I-beta-DaTX was decreased 3.5-fold (KD = 124 nM). However, the four unlabeled DaTXs retained their relative potencies for the inhibition of 125I-alpha-DaTX binding. The molecular weight of the solubilized receptor was estimated to be about 270,000 by sucrose density gradient centrifugation. These data raise the possibility that the inactivating ("A-type") and noninactivating voltage-gated K channels in rat brain may have similar subunits and that the channels may be composed of four Mr 65,000 polypeptides.


Subject(s)
Brain/metabolism , Elapid Venoms/metabolism , Potassium Channels/metabolism , Receptors, Cholinergic/metabolism , Animals , Binding, Competitive , Cations/pharmacology , Centrifugation, Density Gradient , Cross-Linking Reagents , Hydrogen-Ion Concentration , Kinetics , Membrane Potentials , Rats , Solubility , Synaptic Membranes/metabolism
7.
Mol Pharmacol ; 34(2): 152-9, 1988 Aug.
Article in English | MEDLINE | ID: mdl-2457792

ABSTRACT

Venom from the green mamba (Dendroaspis angusticeps) blocked 86Rb efflux through voltage-gated K channels in rat brain synaptosomes. Crude venom inhibited both rapidly inactivating, 4-aminopyridine-sensitive K channels, and noninactivating, phencyclidine-sensitive, K channels. Fractionation of the venom by size exclusion chromatography and cation exchange high performance liquid chromatography yielded four 7000-dalton polypeptides (designated alpha-, beta-, gamma-, and delta-DaTX) that blocked synaptosome K channels. Two of these toxins, alpha- and delta-DaTX (10-100 nM), preferentially blocked the inactivating voltage-gated K channels. The other two toxins, beta- and gamma-DaTX, preferentially blocked the noninactivating voltage-gated K channels. The amino acid composition of these four toxins indicated that alpha-DaTX is identical to dendrotoxin [Br. J. Pharmacol. 77:153-161 (1982)] and toxin C13S2C3 [Hoppe-Seyler's Z. Physiol. Chem. 361:661-674 (1980)]; the composition and partial sequence analysis indicate that delta-DaTX is identical to toxin C13S1C3 [Hoppe-Seyler's Z. Physiol. Chem. 361:661-674 (1980)]. Beta- and gamma-DaTX have not previously been identified. Partial amino acid sequences of beta- and gamma-DaTX and the published sequences of alpha- and delta-DaTX reveal that the C-terminal segments of all four toxins are homologous. The C-terminal segments are also homologous with a number of nontoxic proteinase inhibitors. This raises the possibility that the N-terminal rather than the C-terminal regions are more likely responsible for the K channel blocking activity. The N-terminal portions of alpha- and delta-DaTX have some sequence homologies, but they have no obvious homologies with either beta- or gamma-DaTX. The finding of structurally similar peptide toxins with preferential activities toward different K channels may lead to the development of useful probes of K channel structure and may provide the means to distinguish among different K channels biochemically as well as physiologically.


Subject(s)
Elapid Venoms/pharmacology , Ion Channels/drug effects , Neurotoxins/pharmacology , Potassium/physiology , Animals , Brain , Elapid Venoms/analysis , Elapid Venoms/classification , Electric Conductivity , In Vitro Techniques , Rats , Synaptosomes
8.
Biochem Pharmacol ; 37(3): 511-9, 1988 Feb 01.
Article in English | MEDLINE | ID: mdl-2447895

ABSTRACT

Receptor binding studies were carried out to test whether the rat brain phencyclidine (PCP) receptor is part of a K+ channel. [3H]PCP, and two analogs, [3H]TCP and m-amino[3H]PCP, labeled a single receptor on rat brain synaptic membranes. Each compound bound to a similar number of sites (Bmax = 2.7 pmol bound/mg protein); the apparent dissociation constants for these compounds (KD less than 0.3 microM) decreased with increasing temperature. The following observations indicate that the PCP receptor is part of a K+ channel: (1) aminopyridines (AP) and tetraalkylammonium ions blocked [3H]PCP binding; their respective orders of potency, 4-AP = 3,4-diAP much greater than 3-AP, and tetrabutylammonium (TBA) greater than tetraethylammonium much greater than tetramethylammonium, paralleled their abilities to block K+ channels, (2) the order of potency of PCP and its analogs for binding to the PCP receptor, TCP greater than PCE greater than m-amino-PCP greater than PCP greater than PCPY greater than m-nitro-PCP, paralleled their rank order for blocking brain K+ channels, and (3) the stereospecific displacement of [3H]PCP binding by the isomers of the "sigma" ligands, (+)N-allyl-normetazocine (NANM) greater than (-)NANM, and (-)cyclazocine greater than (+)cyclazocine, and of the dioxolanes, dexoxadrol much greater than levoxadrol, paralleled their abilities to block brain K+ channels. Reciprocal plot and Schild plot analyses indicated that TBA, (+)NANM and dexoxadrol were competitive inhibitors at the PCP receptor, whereas 4-AP had an allosteric interaction.


Subject(s)
Brain/metabolism , Ion Channels/metabolism , Phencyclidine/metabolism , Receptors, Neurotransmitter/metabolism , Animals , Kinetics , Phencyclidine/analogs & derivatives , Potassium/metabolism , Rats , Receptors, Phencyclidine , Synaptic Membranes/metabolism
9.
J Neurosci ; 6(12): 3676-81, 1986 Dec.
Article in English | MEDLINE | ID: mdl-2432204

ABSTRACT

Phencyclidine (PCP) is a schizophrenomimetic drug of abuse. PCP binds with high affinity (apparent dissociation constant, KD less than 10(-6) M) to rat brain membranes and blocks, selectively, a voltage-gated, noninactivating K channel found in rat brain synaptosomes (presynaptic nerve terminals). Thus, it has been proposed that the high-affinity PCP receptor in brain is this K channel. Consistent with this hypothesis, we now show that several K channel blockers displace 3H-PCP from the rat brain receptor. Additionally, we have used a photolabile analog of PCP, m-azido-PCP (Az-PCP), to identify the brain PCP receptor/putative K channel. In the dark, Az-PCP bound reversibly to 2 classes of sites on rat brain synaptic membranes [KD = 0.14 +/- 0.01 microM (n = 5) for high-affinity binding, and KD = 255 +/- 55 microM for low-affinity binding]. Competitive binding studies between Az-3H-PCP and nonlabeled PCP analogs, and between Az-PCP and several tritiated PCP analogs, indicated that the high-affinity Az-PCP binding site is the high-affinity PCP receptor. Several amino-pyridines (APs) and tetraalkylamines (TAAs), which are known to block K channels in excitable cells, were also found to displace 3H-PCP from its high-affinity binding site on rat brain synaptic membranes. The rank order of potency for displacement of 3H-PCP from this site for the APs was 4-AP approximately equal to 3,4-diAP greater than 2-AP much greater than 3-AP; for the TAAs it was TBA greater than TEA much greater than TMA (the tetra-butyl, ethyl, and methyl amines, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)


Subject(s)
Azides/metabolism , Brain/metabolism , Ion Channels/metabolism , Phencyclidine/analogs & derivatives , Potassium/metabolism , Receptors, Neurotransmitter/metabolism , 4-Aminopyridine , Affinity Labels , Aminopyridines/pharmacology , Animals , Cell Membrane/metabolism , Molecular Weight , Phencyclidine/metabolism , Photochemistry , Quaternary Ammonium Compounds/pharmacology , Rats , Receptors, Neurotransmitter/drug effects , Receptors, Phencyclidine
11.
J Neurochem ; 42(3): 705-10, 1984 Mar.
Article in English | MEDLINE | ID: mdl-6319604

ABSTRACT

Protein I has been identified and compared in membranes prepared from chick and rat forebrain. Based upon five criteria known to characterize protein I, namely, (1) its ability to serve as a substrate for both the cyclic AMP-dependent protein kinase and (2) the Ca2+- dependent, calmodulin-requiring protein kinase, (3) its ability to be extracted from membranes at low pH, (4) its characteristic pattern of digestion by collagenase, and (5) its existence as a basic protein, we have determined that although protein I of rat brain consists of the usual doublet polypeptides Ia and Ib, only a single chick forebrain polypeptide is detectable which possesses protein I-like properties.


Subject(s)
Brain Chemistry , Nerve Tissue Proteins/analysis , Phosphoproteins/analysis , Synaptosomes/analysis , Animals , Chickens , Electrophoresis, Polyacrylamide Gel , Microbial Collagenase , Molecular Weight , Rats , Species Specificity , Synapsins , Synaptic Membranes/analysis
12.
Neuroscience ; 10(4): 1497-512, 1983 Dec.
Article in English | MEDLINE | ID: mdl-6664499

ABSTRACT

The protein kinase activities endogenous to synaptic membranes prepared by an identical procedure from avian (chick) and mammalian (rat) brains were compared. Both species showed similar responses towards both protein kinase effector molecules cyclic adenosine monophosphate and Ca2+. Kapp for cyclic adenosine monophosphate-dependent protein kinase activity occurred at 0.4-0.8 microM cAMP and Kapp for Ca2+-dependent, calmodulin-requiring protein kinase activity occurred at 1-2 microM Ca2+ (free ion concentration) both in the absence or presence of calmodulin added to the reaction mixture. This suggests that endogenous calmodulin in these membranes was able to modulate the Ca2+-dependent, calmodulin requiring protein kinase activity. After EGTA-treatment of the membranes to remove endogenous Ca2+ and calmodulin, no significant response towards Ca2+ on the phosphorylation of the membrane polypeptides was measured unless exogenous calmodulin was added after which the Kapp for Ca2+ was increased to 15 microM Ca2+ (free ion concentration). There was a difference in the maximal levels of kinase activity in these membranes with chick membranes containing 57% less cyclic adenosine monophosphate-dependent protein kinase activity, but 65% more Ca2+-dependent, calmodulin-requiring protein kinase activity than the rat membranes. Similar results were determined when either low (5 microM) or high (5.8 microM) concentrations of adenosine 5'-triphosphate were added to the reaction mixtures. Besides certain species differences in the molecular weights of the resulting phosphoproteins, we observed several major differences with respect to the absence or presence of some of the phosphoproteins. Chick synaptic membranes may lack the cyclic adenosine monophosphate-requiring, microtubule-associated phosphoprotein, MAP2, one of the 2 neurospecific, cyclic adenosine monophosphate-requiring and Ca2+, calmodulin-requiring phosphoproteins (Protein Ib, although Protein Ia apparently is present), and the Ca2+-requiring, calmodulin-independent, ACTH-sensitive phosphoprotein, B50. The phenothiazines, trifluoperazine, fluphenazine and chlorpromazine were found to inhibit the Ca2+-dependent, calmodulin-requiring protein kinase activities of both the chick and rat synaptic membranes. This inhibition appeared to be specific for calmodulin because at the same concentrations the phenothiazine analogue, chlorpromazine-sulfoxide, had no effect on this activity. Also found to inhibit Ca2+-dependent calmodulin-requiring protein kinase activity were dibucaine and adrenocorticotropin. These data suggest that rat forebrain synaptic plasma membranes are activated by cyclic adenosine monophosphate


Subject(s)
Brain/enzymology , Nerve Tissue Proteins/metabolism , Protein Kinases/metabolism , Synaptic Membranes/enzymology , Adenosine Monophosphate/pharmacology , Adenosine Triphosphate/pharmacology , Animals , Brain/drug effects , Calcium/pharmacology , Calmodulin/pharmacology , Chickens , Dose-Response Relationship, Drug , Kinetics , Phosphorylation , Rats , Synaptic Membranes/drug effects
13.
J Neurochem ; 40(5): 1349-65, 1983 May.
Article in English | MEDLINE | ID: mdl-6550623

ABSTRACT

Synaptic membranes from rat brain contain several calcium-requiring protein kinase (PK) activities with different substrate specificities: (a) an activity (CaH-PK) effective at high concentrations of Ca2+ ion in the absence of Mg2+ (active on class F substrates); (b) a (Ca + Mg)-PK activity that is mediated by Ca2+ ion in the presence of Mg2+ (active on class B substrates); (c) (Ca-CaM)-PK activities that exhibit simultaneous requirements for both Ca2+ ion and CaM (for class C and D substrates). Also described are three activities (d-f) that do not require Ca2+ ion: (d) a Mg-PK activity in which the presence of Ca2+ causes the inhibition of phosphorylation (active on class A substrates); (e) an activity affecting a diverse group of substrates (class E substrates), the phosphorylation of which occurs in the presence of Mg2+ ion alone (Mg-PK activity) and is unaffected by the addition of Ca2+ ion and CaM, the substrates of which show different responses to several types of inhibitors; and, finally, (f) the previously well characterized cAMP-dependent PK activities. Several of the substrates of these kinases have been identified in a fairly unambiguous manner: among them are P43 (class A), as the alpha subunit of pyruvate dehydrogenase; P54 (class B), as the presynaptic protein B50; and the doublet P75-P80, as proteins IA and IB of Ueda and Greengard. The most interesting activity is that requiring both Ca2+ and CaM. The half-maximal stimulation (K0.5) for Ca2+ in the presence of CaM was found to be 1.0 microM Ca2+F in untreated membranes. There is little change in this value on prior EGTA extraction of the membranes, which removes the bulk of its Ca2+ and reduces its residual CaM by greater than or equal to 50%. The apparent K0.5 for CaM in the presence of excess Ca2+ ion was found to equal 0.4 microgram per reaction mixture (8 micrograms/ml) or 1.35 micrograms per reaction mixture (27 micrograms/ml), for the untreated and EGTA-treated membranes, respectively.


Subject(s)
Calcium/pharmacology , Cerebral Cortex/enzymology , Nerve Tissue Proteins/metabolism , Protein Kinases/metabolism , Synaptic Membranes/enzymology , Animals , Calmodulin/metabolism , Electrophoresis, Polyacrylamide Gel , Kinetics , Male , Molecular Weight , Nerve Tissue Proteins/isolation & purification , Phosphorylation , Rats , Rats, Inbred Strains , Substrate Specificity , Vanadates , Vanadium/pharmacology
14.
J Bioenerg Biomembr ; 14(5-6): 527-47, 1982 Dec.
Article in English | MEDLINE | ID: mdl-6298199

ABSTRACT

We have investigated the localization of a set of intrinsic ATPase activities associated with purified synaptic plasma membranes and consisting of (a) a Mg2+-ATPase; (b) an ATPase active at high concentrations of Ca2+ in the absence of Mg2+ (CaH-ATPase); (c) a Ca2+ requiring Mg2+-dependent ATPase (Ca + Mg)-ATPase, stimulated by calmodulin (Ca-CaM-ATPase); (d) a Ca2+-dependent ATPase stimulated by dopamine (DA-ATPase); and (e) the ouabain-sensitive (Na + K)-ATPase. The following results were obtained: (1) All ATPases are largely confined to the presynaptic membrane; (2) the DA-, (Ca + Mg)-, (Ca-CaM)-, and (Na + K)-ATPases are oriented with their ATP hydrolysis sites facing the synaptoplasm; (3) the Mg- and CaH-ATPases are oriented with their ATP hydrolysis sites on the junctional side of the presynaptic membrane and are therefore classified as ecto-ATPases of as yet unknown function.


Subject(s)
Adenosine Triphosphatases/analysis , Nerve Endings/enzymology , Animals , Digitonin/pharmacology , In Vitro Techniques , Male , Ouabain/pharmacology , Rats , Rats, Inbred Strains , Saponins/pharmacology , Sodium-Potassium-Exchanging ATPase/metabolism , Subcellular Fractions/enzymology , Synaptosomes/enzymology
17.
J Neurochem ; 37(6): 1407-18, 1981 Dec.
Article in English | MEDLINE | ID: mdl-6120995

ABSTRACT

We have investigated the properties of several ATPases present in synaptic membrane preparations from the cerebral cortex of rat. In addition to the intrinsic (Na+ + K+)-ATPase and a low level of contaminating Mg2+-ATPase of mitochondrial origin, both of which could be controlled by the addition of ouabain and azide, respectively, four activities were studied: (1) a Mg2+-ATPase; (2) a Mg2+-independent activity requiring Ca2+ ions at high concentrations; (3) a (Ca2+ + Mg2+)-ATPase with a high affinity for Ca2+, which were enhanced further (4) by the inclusion of calmodulin (33 nM for half-maximal activity). In the presence of 0.5 mM-EGTA in the buffer used, half saturation for these respective metal ions was observed at 0.9 mM for (1), 1.0 mM for (2), and approximately 0.3 mM for (3) and (4); the latter values correspond to concentrations of free Ca2+ of 0.38 and 0.18 microM for (3) and (4), respectively. The level of activities observed, all in nmol X min-1 X mg-1, under optimal conditions of 37 degrees C, was in a number of preparations (n in parenthesis): for (1) 446 +/- 19 (19); for (2) 362 +/- 18 (3) for (3) 87 +/- 13 (12); and for (4) 161 +/- 29 (12). The (Ca2+ + Mg2+)-ATPase, both in the presence and absence of calmodulin, could be inhibited specifically by a number of agents (approximate I0.5 in parentheses) which, at these concentrations, showed little or no potency against the other activities; among them were vanadate (less than or equal to 10 microM), La3+ (75 microM), trifluoperazine, and other phenothiazines (50 microM). These properties suggest that the (Ca2+ + Mg2+)-ATPase described may be responsible for calcium transport across one (or more) of the several membranes present in nerve endings and contained in the preparation used.


Subject(s)
Adenosine Triphosphatases/metabolism , Calcium/pharmacology , Cerebral Cortex/enzymology , Synaptic Membranes/enzymology , Animals , Ca(2+) Mg(2+)-ATPase , Calcium-Transporting ATPases/metabolism , Cations, Monovalent , Male , Ouabain/pharmacology , Rats , Rats, Inbred Strains , Sodium-Potassium-Exchanging ATPase/metabolism
18.
Brain Res Bull ; 7(1): 57-61, 1981 Jul.
Article in English | MEDLINE | ID: mdl-6456038

ABSTRACT

A major phosphoprotein of synaptic membranes, the phosphorylation of which is stimulated by Ca2+ and inhibited by ACTh, appears to be identical with protein B-50 described by Zwiers, Schotman and Gispen [40]. We have investigated its subsynaptic localization by means of a variety of subfractionation techniques and compared it with that of a number of other phosphoproteins found in synaptic membranes. It appears to be predominantly, if not exclusively, associated with presynaptic membranes of low bouyant density. This localization pattern is similar to, but somewhat more extreme than that exhibited by Protein I, as a brain specific phosphoprotein studied by Greengard and his collaborators [11].


Subject(s)
Phosphoproteins/metabolism , Synapses/metabolism , Animals , Cerebral Cortex/metabolism , Electrophoresis, Polyacrylamide Gel , GAP-43 Protein , Nerve Tissue Proteins/metabolism , Rats , Synapsins , Synaptic Membranes/metabolism , Synaptic Vesicles/metabolism , Synaptosomes/metabolism
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