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  • 1
    Electronic Resource
    Electronic Resource
    Sialosylcholesterol Effects on Reconstitution of Microfilament and Glia Filament (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 62 (1994), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The effects of α-sialosylcholesterol (α-SC) on formation of either microfilament or glia filament of rat astrocytes were investigated using a reconstitution system. Polymerization of the depolymerized microfilament preparation that had been extracted from a crude cytoskeletal fraction of rat astrocytes, in the presence of 100 mM KCI and 10 mM MgCI2, was suppressed in a dose-dependent manner by α-SC. α-SC inhibited polymerization of G-actin in a similar manner. The intensity of a-SC inhibition of G- actin polymerization was as great as that of microfilament polymerization, suggesting that the inhibition of microfilament polymerization by α-SC was due to the direct action of α-SC on actin, the main component of microfilament. α-SC depolymerized partly the polymerized microfilament preparation, which resembled F-actin (microfilament-like filaments). α-SC suppressed, in a dose-dependent manner, polymerization of a glia filament preparation that had been extracted from astrocyte cytoskeletons in the presence of phalloidin. An increase in the amount of added α-SC (up to 15 nM) decreased the amount of the larger glia filament-like filaments, which were 10 nm thick and centrifuged down at 16,000 g for 30 min, and increased that of smaller ones precipitated only after centrifugation at 100,000 g for 1 h. The lower the concentration of the depolymerized glia filament extract, the greater was the inhibition by α-SC of the polymerization. α-SC repressed polymerization of vimentin, the dominant component of glia filament. Vimentin polymerization was more strongly inhibited by α-SC than polymerization of glia filament was. The findings suggested that α-SC suppressed polymerization of glia filament through a direct action on vimentin and that the glia filament-associated proteins increased its structural stability in the presence of α-SC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1994.62010235.x
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  • 2
    Electronic Resource
    Electronic Resource
    Characterization of Ca2+/Calmodulin-Dependent Protein Kinase Associated with Rat Cerebral Synaptic Junction: Substrate Specificity and Effect of Autophosphorylation (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 47 (1986), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The Ca2+/calmodulin (CaM)-dependent protein kinase associated with rat cerebral synaptic junction (SJ) was characterized, using the SJ fraction as the enzyme preparation, to clarify the functional significance of the enzyme in situ. The protein kinase was greatly activated in the presence of micromolar concentrations of both Ca2+ and calmodulin (EC50 for Ca2+, 1.0 μM; that for CaM, 100 nM). The Km for ATP was 150 μM. SJ proteins were phosphorylated without a lag time, and the phosphorylation reached its maximum within 2–10 min at 25°C. The endogenous substrates consisted of four major (160K, 120K, 60K, and 51K Mr) and 10 minor proteins. Compared with the endogenous substrate phosphorylation, the phosphorylation of exogenously added proteins (myosin light chains from chicken muscle, casein, arginine-rich histone, microtubule-associated protein-2, τ-protein, and tubulin) was weak, although they are expected to be good substrates for the soluble form of the Ca2+/CaM-dependent protein kinase. Autophosphorylation of the enzyme in SJ inhibited its activity and did not alter the subcellular distribution of the enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1986.tb04548.x
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  • 3
    Electronic Resource
    Electronic Resource
    Mechanisms of α-Sialosyl Cholesterol Action to Suppress Both Cyclic AMP Production and DNA Synthesis of Rat Glial Cells (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 61 (1993), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: α-Sialosyl cholesterol (α-SC) that elicited morphological differentiation of rat astrocytes not only lowered intracellular cyclic AMP (cAMP) levels but also inhibited cAMP production induced by either α-isoproterenol, cholera toxin, or forskolin. The targets of α-SC in the cAMP production system of rat astrocytes were investigated to understand the mechanism of the a-SC action on cAMP production. cAMP production evoked by a-isoproterenol (1 μM) was entirely canceled by β blockers such as propranolol and timolol (1 μM), but not by α-SC. Concentrations of α-SC greater than 15 μM were required for 50% inhibition of the activation by a β agonist. Although α-SC inhibited in a dose-dependent manner the activities of membrane-associated adenylate cyclase that had been stimulated by either GTPγS or forskolin, α-SC inhibited neither GTP-binding activities nor GTPase activities of the membrane-associated G proteins. These findings suggest that α-SC suppresses adenylate cyclase directly, but not β receptors or G proteins, and that it promotes the morphological differentiation of rat astrocytes through a mechanism regulating directly the cytoskeletal organization, regardless of intracellular cAMP level. α-SC (30 μM) suppressed 40% of DNA synthesis in the cell-free system, which contained the cytosolic extracts and the nucleus fraction prepared from rat astrocytoma C6 cells. Approximately 25% of α-SC incorporated in the astrocyte cytoplasm was transferred to the nuclei by 10 min after the addition. Thus, it is likely that α-SC that had been incorporated in the cytosol suppressed adenylate cyclase by acting from the cytosolic side of the plasma membrane, and separately suppressed nuclear DNA synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1993.tb03539.x
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  • 4
    Electronic Resource
    Electronic Resource
    Rapid Translocation of Cytosolic Ca2+/Calmodulin-Dependent Protein Kinase II into Postsynaptic Density After Decapitation (1994)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 63 (1994), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The postsynaptic density (PSD) fraction prepared from rat forebrains frozen with liquid nitrogen immediately after dissection (within 30 s after decapitation) contained major postsynaptic density protein (mPSDp), α subunit of Ca2+/calmodulin-dependent protein kinase II (CaMKII) at a level of merely 2.7% of the total protein. The content of the protein in the fraction was increased to ∼10% by placing the forebrains on ice for a few minutes. Accumulation, but to a lesser extent, of the protein after placement was also observed in the particulate, synaptosome, and synaptic plasma membrane fractions with its concomitant decrease in the cytosolic fraction. The distribution change may be translocation of the protein, because the amounts of the losses of the protein in the cytosolic fraction were balanced by the gains in the particulate fractions. By translocation, CaMKII became Triton X-100 insoluble and partially inactivated. The amount of CaMKII transferred from the cytosol to particulate fractions at 0°C was about the same as that contained in the conventional PSD fraction. Furthermore, the thickness of the PSD was increased by the treatment of the forebrains at 37°C, by which the content of CaMKIIα in the PSD fraction was increased to twofold. These results suggest that most of the CaMKII α subunit associated with the PSD fraction (mPSDp) is translocated from cytosol after decapitation. We also showed similar translocation of CaMKIIβ/β′.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1994.63041529.x
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  • 5
    Electronic Resource
    Electronic Resource
    Independent Protein Kinases Associated with the Rat Cerebral Synaptic Junction: Comparison with Cyclic AMP-Dependent and Ca2+/Calmodulin-Dependent Protein Kinases in the Synaptic Junction (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 48 (1987), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Independent protein kinases in the synaptic junction (SJ) isolated from rat cerebrum were characterized. SJ showed a protein kinase activity, phosphorylating intrinsic proteins, even in the absence of cyclic AMP or Ca2+ plus calmodulin (CaM) exogenously added. The activity was affected neither by Ca2+ concentrations in the physiological fluctuation range nor by the addition of specific ligands such as glutamate, aspartate, acetylcholine, and concanavalin A. The activity was not due to cyclic AMP-dependent protein kinase in SJ, since the activity was not inhibited by an inhibitor protein for cyclic AMP-dependent protein kinase, and since synapsin I was not specifically phosphorylated whereas cyclic AMP-dependent kinase appeared to phos-phorylate selectively the protein in SJ. Phosphorylation of SJ proteins by the independent kinases was about one-third of that of the Ca2+/CaM-dependent protein kinase intrinsic to SJ. The apparent Km for ATP was estimated to be 700 μM. Proteins of 16K Mr and 117K Mr were specifically phosphorylated under the basic condition (in the absence of the substances known to activate specifically protein kinases), as well as six other proteins both under the basic conditions and in the presence of Ca2+ and CaM. The phosphorylation of 150K Mr, 60K Mr, 51K Mr, and 16K Mr SJ proteins was enhanced after prephosphorylation of SJ proteins by intrinsic kinase in the presence of Ca2+ and CaM. This fact suggested that a part of the independent kinase activity was attributable to the autonomous form of Ca2+/ CaM-dependent kinase which was derived from its auto-phosphorylation, and that the Ca2+/CaM-dependent auto-phosphorylation affected the microtubules in the postsyn-aptic region inasmuch as the 16K Mr protein occurred in both brain cytosol and microtubule protein fraction prepared from rat brain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1987.tb05728.x
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  • 6
    Electronic Resource
    Electronic Resource
    Cyclic Nucleotides and the Activity of Glia Maturation Factor in the Hypoplastic Cerebellum of Developing Jaundiced Gunn Rats (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 50 (1988), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Developmental changes of cyclic nucleotides were studied in the hypoplastic cerebellum of jaundiced Gunn rats over the period of postnatal days 8 to 30. The mitogenic activity of glia maturation factor was also measured at day 15. In jaundiced homozygotes(jj), the amount of cyclic GMP on a protein basis was not significantly different from that in control heterozygotes (j+) at either day 8 or 15, but at day 30 it was reduced to about 19% of the control. On the other hand, a lowered nucleotide level on a wet weight basis in jj rats was already statistically significant at day 15. In contrast to cyclic GMP, the rates of increase of cyclic AMP on a wet weight basis were almost the same in the two groups of rats, but the nucleotide levels on a protein basis at days 15 and 30 were a little, but significantly, higher in jj rats than in j+ rats. The activity of glia maturation factor in jj rats was found to be 1.5-3 times as high as that in j+ rats. Possible implications of the present results are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1988.tb02970.x
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  • 7
    Electronic Resource
    Electronic Resource
    Pethidine and levallorphan (1959)
    Oxford, UK : Blackwell Publishing Ltd
    Anaesthesia 14 (1959), S. 0 
    Details
    ISSN: 1365-2044
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2044.1959.tb13781.x
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  • 8
    Electronic Resource
    Electronic Resource
    Photoinduced electron transfer on a single .alpha.-helical polypeptide chain (1989)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 111 (1989), S. 6790-6796 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00199a044
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  • 9
    Electronic Resource
    Electronic Resource
    Circulatory responses to epidural blockade of treated and untreated hypertensive patients (1989)
    Springer
    Journal of anesthesia 3 (1989), S. 132-137 
    Details
    ISSN: 1438-8359
    Keywords: Cervical ; Thoracic and lumbar epidural blockade ; Treated and untreated hypertension ; Blood pressure ; Pulse rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The circulatory effects of epidural blockade were studied in 82 hypertensive patients. To compare the circulatory responses to epidural blockade between treated and untreated hypertensive patients, patients were divided into 60 treated and 22 untreated hypertensive patients groupes, and to confirm the magnitude of hemodynamic changes according to the segment of epidural approach, each group was then subdivided into 3 groups as cervical, thoracic and lumbar. The blood pressure and the pulse rate were measured before and after establishment of epidural blockade. The baseline blood pressure of untreated group was significantly higher than that of treated one (P 〈 0.05), but there was no difference between two groups in the initial pulse rate. At 20 min after meperidine administration to epidural space, blood pressure drop was more pronounced in untreated thoracic subgroup than in treated one (P 〈 0.05), but there was no significant difference in blood pressure drop between treated and untreated groups of cervical and lumbar blockade. Regarding the pulse rate change, there was no significant difference between treated and untreated cases of all the subgroups. The rate of fluid load required to maintain the adequate blood pressure in the first 20 min of epidural blockade was more in treated than in untreated cases of cervical subgroup. During surgery the administration of vasopressor agents was more frequently required to maintain blood pressure in treated and untreated thoracic subgroups, while the administration of vasodilator agents was more frequent in treated and untreated cases of cervical and thoracic subgroups. The incidence of rebound hypertension was relatively high in untreated cervical and thoracic subgroups as compared to treated ones. (Jin HY, Tanaka R: Circulatory responses to epidural blockade of treated and untreated hypertensive patients. J Anesth 3: 132–137, 1989)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s0054090030132
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  • 10
    Electronic Resource
    Electronic Resource
    Mechanism of lipid activation of Na, K, Mg-activated adenosine triphosphatase and K, Mg-activated phosphatase of bovine cerebral cortex (1971)
    Springer
    The journal of membrane biology 4 (1971), S. 42-51 
    Details
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Na+, K+, Mg++-activated adenosine triphosphatase and K+, Mg++-activatedp-nitrophenyl phosphatase prepared from a membrane fraction of bovine cerebral cortex were studied with regard to the manner of their activation by phospholipids, using phosphatidyl serine, lysolecithin, monodecyl and didecyl phosphates. The kinetic and chromatographic studies suggested the following. (1) When the enzyme proteins bind the phospholipids in a proper ratio, they attain the optimum activation. (2) The binding causes a simple conversion of the enzymes from an inactive form to a fully activated form. (3) The lipids in both micellar form and molecular dispersion activate the enzymes. (4) Of the proteins contained in the enzyme preparation, only a group of proteins possessing the ATPase and the phosphatase activities bind phospholipids, and the amount of the bound lipids is limited.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02431960
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