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1.
Pharmacopsychiatry ; 46(6): 221-6, 2013 Sep.
Article in English | MEDLINE | ID: mdl-23963965

ABSTRACT

The present study aimed at investigating the effectiveness and tolerability of -bupropion hydrochloride extended release (XL) in major depressive disorder (MDD) patients with atypical features (AF).51 patients were prescribed bupropion XL for 8 weeks (6 visits: screening, baseline, weeks 1, 2, 4 and 8). The primary efficacy measure was a change of the Structured Interview Guide for the Hamilton Depression Rating Scale-Seasonal Affective Disorder Version (SIGH-SAD) from baseline to endpoint. Secondary efficacy measures included the SIGH-SAD atypical symptoms subscale, Clinical Global Impression-Severity (CGI-S), Sheehan Disability Scale (SDS) and Epworth Sleepiness Questionnaire (ESQ). Response or remission was defined as ≥50% reduction or ≤7 in SIGH-SAD total scores, respectively, at end of treatment.The HAM-D-29 total score reduced by 55.3% from baseline (27.3±6.5) to end of treatment (12.2±6.3) (p<0.001). Atypical symptom subscale scores also reduced by 54.5% from baseline (9.2±3.0) to end of treatment (4.2±2.8) (p<0.001). At the end of treatment, 24.4% (n=10) and 51.2% (n=21) subjects were classified as remitters and responders, respectively. The most frequently reported AEs were headache (13.7%), dry mouth (11.8%), dizziness (9.8%), and dyspepsia (9.8%).Our preliminary study indicates that bupropion XL may be beneficial in the treatment of MDD with atypical features. Adequately powered, randomized, double-blind, placebo-controlled trials are necessary to determine our results.


Subject(s)
Antidepressive Agents, Second-Generation/therapeutic use , Bupropion/therapeutic use , Depressive Disorder, Major/drug therapy , Adult , Antidepressive Agents, Second-Generation/administration & dosage , Antidepressive Agents, Second-Generation/adverse effects , Bupropion/administration & dosage , Bupropion/adverse effects , Delayed-Action Preparations/adverse effects , Depressive Disorder, Major/diagnosis , Female , Humans , Male , Middle Aged , Psychiatric Status Rating Scales , Single-Blind Method
2.
Rhinology ; 51(3): 280-6, 2013 Sep.
Article in English | MEDLINE | ID: mdl-23943738

ABSTRACT

BACKGROUND: Isolated sphenoid sinus disease (ISSD) is rare. Fungus ball (FB) is the third most common ISSD. We analysed the characteristics of isolated sphenoid FB based on demographic data, presenting symptoms, preoperative computed tomography (CT), magnetic resonance imaging (MRI), and treatment outcomes. METHODOLOGY: From 1999 to 2012, 29 patients were identified with isolated sphenoid FB. Demographic data; clinical characteristics; endoscopic, CT, and MRI findings and treatment outcomes were retrospectively analysed. RESULTS: The most common symptom was headaches, which were localized in various regions of the brain. Other symptoms were uncommon. The most common CT findings were sclerosis, calcification, enlarged sinus and total opacification. On T2-weighted MRI images, we most commonly observed signal void. Endoscopic transnasal paraseptal sphenoidotomy was performed in all patients, and for most, this was performed under local anaesthesia. No recurrence was observed in any patient. CONCLUSION: Isolated sphenoid FB is predominantly observed in older women, and it is characterised by headaches and sclerosis of the sinus wall observed on CT scans. In cases of isolated sphenoid FB, endoscopic transnasal paraseptal sphenoidotomy can be successfully performed under local anaesthesia, which may facilitate rapid recovery and a low morbidity rate.


Subject(s)
Mycoses/diagnosis , Mycoses/surgery , Sphenoid Sinus/microbiology , Sphenoid Sinusitis/diagnosis , Sphenoid Sinusitis/surgery , Adult , Aged , Endoscopy , Female , Humans , Magnetic Resonance Imaging , Male , Middle Aged , Mycoses/microbiology , Retrospective Studies , Sphenoid Sinusitis/microbiology , Tomography, X-Ray Computed , Treatment Outcome
3.
Br J Radiol ; 84(1005): e179-81, 2011 Sep.
Article in English | MEDLINE | ID: mdl-21849359

ABSTRACT

Cytomegalovirus (CMV) ventriculoencephalitis is a rare but serious potential complication of CMV infection in immunocompromised patients. Characteristic diffusion-weighted imaging findings can be helpful for the diagnosis of CMV ventriculitis, as in this case report.


Subject(s)
Cerebral Ventriculitis/diagnosis , Cytomegalovirus Infections/diagnosis , Diffusion Magnetic Resonance Imaging , Immunocompromised Host , Cerebral Ventriculitis/immunology , Cytomegalovirus Infections/immunology , Diffusion Magnetic Resonance Imaging/methods , Fatal Outcome , Humans , Male , Young Adult
4.
Cell Death Differ ; 17(12): 1830-41, 2010 Dec.
Article in English | MEDLINE | ID: mdl-20448643

ABSTRACT

The zinc-finger protein A20 has crucial physiological functions as a dual inhibitor of nuclear factor-κB (NF-κB) activation and apoptosis in tumor necrosis factor (TNF) receptor 1 signaling pathway. Although the molecular basis for the anti-NF-κB function of A20 has been well elucidated, the anti-apoptotic function of A20 is largely unknown. Here, we report a novel mechanism underlying the anti-apoptotic function of A20: A20 blocks TNF-induced apoptosis through suppression of c-jun N-terminal kinase (JNK) by targeting apoptosis signal-regulating kinase1 (ASK1). First, the ectopic expression of A20 drastically inhibits TNF-induced JNK activation and apoptosis in multiple cell types including those deficient of NF-κB activation. Unexpectedly, the blunting effect of A20 on TNF-induced JNK activation is not mediated by affecting the TNFR1 signaling complex formation. Instead, A20 interacts with ASK1, an important MAPKK kinase in the JNK signaling cascade. More importantly, overexpression of wild-type A20, but not of mutant A20 (ZnF4; C624A, C627A), promotes degradation of the ASK1 through the ubiquitin-proteasome system. Taken together, the results from this study reveal a novel anti-apoptotic mechanism of A20 in TNF signaling pathway: A20 binds to ASK1 and mediates ASK1 degradation, leading to suppression of JNK activation and eventually blockage of apoptosis.


Subject(s)
Apoptosis , Intracellular Signaling Peptides and Proteins/metabolism , JNK Mitogen-Activated Protein Kinases/metabolism , MAP Kinase Kinase Kinase 5/metabolism , Nuclear Proteins/metabolism , Tumor Necrosis Factor-alpha/metabolism , Cell Line, Tumor , DNA-Binding Proteins , Humans , NF-kappa B/metabolism , Receptors, Tumor Necrosis Factor, Type I/metabolism , Signal Transduction , TNF Receptor-Associated Factor 2/metabolism , Tumor Necrosis Factor alpha-Induced Protein 3 , Ubiquitination
5.
Rheumatology (Oxford) ; 47(3): 301-8, 2008 Mar.
Article in English | MEDLINE | ID: mdl-18276737

ABSTRACT

OBJECTIVE: Resveratrol is a naturally occurring polyphenol, which possesses chemotherapeutic potential through its ability to trigger apoptosis. The objective of this study was to investigate the major determinant for the apoptotic cell death induction by resveratrol in fibroblast-like synoviocytes (FLS) derived from patients with RA. METHODS: The effect of resveratrol on apoptotic cell death was quantified in a population of subG1 in RA FLS by flow cytometry. The underlying signalling mechanism for apoptotic death was examined by analysing mitochondrial membrane potential, activation of the caspase cascade and translocation of Bid. RESULTS: We show that activation of caspase-8 is essential for triggering resveratrol-induced apoptotic signalling via the involvement of the mitochondrial pathway in RA FLS. Our findings also suggest that this enhanced apoptosis caused by resveratrol occurred in RA FLS irrespective of p53 status. Exposure to resveratrol caused extensive apoptotic cell death, along with a caspase-dependent (activation of caspase-9 and -3, poly ADPribose polymerase (PARP) cleavage and mitochondrial cytochrome c release) or caspase-independent [translocation of apoptosis-inducing factor (AIF) to the nucleus] signalling pathway. Analysis of upstream signalling events affected by resveratrol revealed that the activated caspase-8 triggered mitochondrial apoptotic events by inducing Bid cleavage without any alteration in the levels of Bax, Bcl-xL or Bcl2. The caspase-8 inhibitor or over-expression of crmA abrogated cell death induced by resveratrol and prevented processing of the downstream cascade. CONCLUSION: The results suggest that resveratrol causes activation of caspase-8, which in turn results in modulation of mitochondrial apoptotic machinery to promote apoptosis of RA FLS.


Subject(s)
Apoptosis Inducing Factor/metabolism , Apoptosis/drug effects , Arthritis, Rheumatoid/physiopathology , Caspase 8/metabolism , Stilbenes/pharmacology , Apoptosis Inducing Factor/drug effects , Arthritis, Rheumatoid/metabolism , Caspase 8/drug effects , Cells, Cultured , Fibroblasts/cytology , Fibroblasts/drug effects , Fluorescent Antibody Technique , Humans , Membrane Potentials , Mitochondria/physiology , Probability , Resveratrol , Sensitivity and Specificity , Synovial Membrane/cytology , Synovial Membrane/drug effects
6.
Environ Technol ; 24(1): 31-42, 2003 Jan.
Article in English | MEDLINE | ID: mdl-12641250

ABSTRACT

A series of bench-scale nitrification/denitrification tests were carried out with both suspended growth and hybrid bioreactors. The hybrid reactor was filled with plastic (polyethylene) media to evaluate the effects of biofilm. Two types of reactor configurations were tested; 4-compartment and 6-compartment modes. The experiments were initiated with a half-strength pulp and paper wastewater and its strength increased stepwise to the raw wastewater. Solid retention time was fixed at 10 days after a start-up period while hydraulic retention time was extensively varied from 3.5 to 0.5 days. The results from each type of reactor were compared in terms of nitrification/denitrification efficiency and stability. Experimental results demonstrate that the hybrid system showed greater stability in nitrification and higher denitrification efficiency than the suspended growth system. In the hybrid system, attached volatile solids formed 61- 72% of total volatile solids in the reactor and the amount of attached volatile solids insignificantly varied with the organic loading rate (0.37 - 2.76 kg COD M(-3) d(-1)) after initial biomass attachment. Under the conditions tested (0.1 - 2.8 kg COD m(-3) d(-1)), organic loading rate insignificantly influenced the nitrification. Better performance was obtained in denitrification when the anoxic zone was better isolated from the aerobic compartments (6-compartment mode). Overall, the hybrid system with fixed-film growth had better resistance to upset caused by transients such as changes in influent composition or hydraulic retention time.


Subject(s)
Bioreactors , Industrial Waste , Nitrogen/metabolism , Quaternary Ammonium Compounds/chemistry , Sulfites/chemistry , Waste Disposal, Fluid/methods , Water Purification/methods , Biofilms , Nitrogen/isolation & purification , Volatilization
7.
Biochem Biophys Res Commun ; 284(3): 607-13, 2001 Jun 15.
Article in English | MEDLINE | ID: mdl-11396944

ABSTRACT

It has been known that the expression of inducible nitric oxide synthase (iNOS) is up-regulated during hepatic regeneration. The present study characterized the molecular mechanisms involved in the transcriptional activation of iNOS gene by using the serum after partial hepatectomy (post-PH serum) in vitro. The post-PH serum rapidly induced iNOS mRNA expression, which was blocked by anti-tumor necrosis factor-alpha (TNF-alpha) antibody in BNL CL.2 cells, murine embryonic liver cell line. In addition, EMSAs using a NF-kappa B-specific oligomer showed that the up-regulated iNOS mRNA expression in cells treated with post-PH serum correlated with transient activation of NF-kappa B complex (p50/p65 heterodimer). Transient transfection of BNL CL.2 cells with iNOS promoter linked to a CAT reporter gene showed the transcriptional activation of iNOS promoter by post-PH serum. Furthermore, site-directed mutational analysis of the two NF-kappa B sites individually or in combination revealed that iNOS expression by post-PH serum is regulated by the downstream NF-kappa B site, but not by upstream NF-kappa B site. Taken together, these results suggest that the downstream NF-kappa B site acts as an essential component for the iNOS expression by post-PH serum during hepatic regeneration.


Subject(s)
Blood , Hepatectomy , NF-kappa B/metabolism , Nitric Oxide Synthase/genetics , Animals , Antibodies/immunology , Cell Line , Culture Media , Kinetics , Liver Regeneration , Mice , Nitric Oxide Synthase/biosynthesis , Nitric Oxide Synthase Type II , Promoter Regions, Genetic , RNA, Messenger/biosynthesis , Rats , Rats, Sprague-Dawley , Response Elements , Transcriptional Activation , Tumor Necrosis Factor-alpha/immunology
8.
Biochem Biophys Res Commun ; 272(3): 758-64, 2000 Jun 16.
Article in English | MEDLINE | ID: mdl-10860828

ABSTRACT

Acetaminophen is a widely used analgesic and anti-inflammatory drug that is considered a good alternative to salicylates for individuals who cannot tolerate salicylates. Nitric oxide (NO) synthesized by inducible nitric oxide synthase (iNOS) has been implicated as a mediator of inflammation. Recent evidence suggests that anti-inflammatory effect of salicylates lies in the inhibition of iNOS, but nothing has been reported about the direct effect of iNOS expression by acetaminophen. The present study was designed to elucidate sequentially the action mechanisms of acetaminophen and salicylates (aspirin and sodium salicylate) on lipopolysaccharide (LPS) plus interferon-gamma (IFN-gamma)-induced iNOS expression in RAW 264.7 macrophages. Both acetaminophen and salicylates inhibited NO production and iNOS protein expression in a dose dependent manner. Acetaminophen inhibited iNOS mRNA expression, promoter activity of iNOS gene and nuclear factor-kappa B (NF-kappaB) binding activity induced by LPS plus IFN-gamma, whereas salicylates did not show any effect on them. In addition, salicylates did not affect on iNOS mRNA stability induced by LPS plus IFN-gamma. Furthermore, the inhibition of iNOS protein expression and NO production by salicylates was disappeared when salicylates were added for only 5 h to inhibit the early event of iNOS expression. Aspirin also dose dependently inhibited iNOS enzyme activity in cell-free extracts, whereas no significant differences were observed in extracts treated with sodium salicylate or acetaminophen. These findings suggest that acetaminophen may exert analgesic or anti-inflammatory effect by inhibiting iNOS expression induced by LPS plus IFN-gamma at transcriptional level by suppression of NF-kappaB binding activity, whereas salicylates exert its effect by inhibiting iNOS expression at the translational or posttranslational level.


Subject(s)
Acetaminophen/pharmacology , Anti-Inflammatory Agents/pharmacology , Gene Expression Regulation, Enzymologic/drug effects , Macrophages/drug effects , NF-kappa B/metabolism , Nitric Oxide Synthase/genetics , Salicylates/pharmacology , Animals , Aspirin/pharmacology , Catalysis/drug effects , Cell Extracts , Cell Line , DNA/genetics , DNA/metabolism , Dose-Response Relationship, Drug , Interferon-gamma/antagonists & inhibitors , Interferon-gamma/pharmacology , Lipopolysaccharides/antagonists & inhibitors , Lipopolysaccharides/pharmacology , Macrophages/cytology , Macrophages/enzymology , Macrophages/metabolism , Mice , Nitric Oxide/metabolism , Nitric Oxide Synthase/antagonists & inhibitors , Nitric Oxide Synthase/metabolism , Nitric Oxide Synthase Type II , Promoter Regions, Genetic/genetics , Protein Binding/drug effects , Protein Biosynthesis/drug effects , RNA Stability/drug effects , RNA, Messenger/genetics , RNA, Messenger/metabolism , Sodium Salicylate/pharmacology
9.
Immunopharmacology ; 47(1): 35-44, 2000 Apr.
Article in English | MEDLINE | ID: mdl-10708808

ABSTRACT

Various cytokines and reactive oxygen species (ROS) play a fundamental role in the inflammatory and immunologic processes of rheumatoid arthritis (RA). Methotrexate (MTX) is one of the disease-modifying anti-rheumatic drugs and its effect may be partly due to the modulation of immunologic or inflammatory reactions by some cytokines. In the present study, we investigated the effects of MTX on the gene expression and synthesis of interleukin-6 (IL-6), and the proliferative activity and the production of ROS in the fibroblast-like synoviocytes (FLSs) obtained from the patient of RA. The expression or production of IL-6 was induced spontaneously, and augmented by the addition of recombinant human IL-6 or recombinant human IL-1 beta and TNF-alpha in FLSs. These spontaneous and augmented IL-6 expressions or productions were suppressed by treatment with low-concentration of MTX (1 microg/ml). Also, IL-6 stimulated the proliferation of FLSs, and this IL-6 driven proliferation was inhibited with the treatment of MTX or N-acetylcysteine (NAC, 1 mM). Furthermore, ROS production in FLSs was increased significantly by IL-6, and its effect was also abrogated in the presence of MTX or NAC. These results suggest that inflammatory reaction in the synovium of RA patients could be augmented by the autocrine or other cytokine-induced production of IL-6 with subsequent generation of ROS in the synoviocytes, and the modulations of IL-6 synthesis and ROS production may contribute to the therapeutic effects of MTX for RA.


Subject(s)
Arthritis, Rheumatoid/metabolism , Interleukin-6/pharmacology , Methotrexate/pharmacology , Reactive Oxygen Species/metabolism , Synovial Fluid/cytology , Adenosine/pharmacology , Arthritis, Rheumatoid/pathology , Cell Culture Techniques , Cell Division/drug effects , Dose-Response Relationship, Drug , Gene Expression/drug effects , Humans , Inflammation Mediators/antagonists & inhibitors , Interleukin-1/pharmacology , Interleukin-6/biosynthesis , Interleukin-6/genetics , Knee Joint/pathology , RNA, Messenger/biosynthesis , Synovial Fluid/metabolism , Tumor Necrosis Factor-alpha/pharmacology
10.
Biochem Biophys Res Commun ; 261(3): 917-22, 1999 Aug 11.
Article in English | MEDLINE | ID: mdl-10441525

ABSTRACT

It has been known that many immediately early genes are expressed during ischemia/reperfusion (I/R) injury. Here, employing a model of hepatic I/R, we show that inducible nitric oxide synthase (iNOS) is induced via the activation of nuclear factor kappaB (NF-kappaB) after I/R in rat liver. When liver was subjected to ischemia followed by reperfusion, but not ischemia alone, an NF-kappaB complex composed of p50/p65 heterodimer and p50 homodimer was rapidly activated within 1 h and remained elevated for up to 3 h, and then tended to decline after 5 h of reperfusion. Also, the expression of iNOS mRNA was initiated after 1 h and continued to increase after 5 h of reperfusion during the time course studied. This upregulated iNOS mRNA expression coincides with increased iNOS enzyme activity and NF-kappaB binding activity after hepatic I/R. Administration of N-acetylcysteine (NAC, 20 mg/kg i.v. 10 min before reperfusion), an antioxidant, not only significantly inhibited the expression of iNOS mRNA but also blocked upregulated NF-kappaB binding activity after reperfused liver. These results suggest that NF-kappaB is activated by oxidative stress during hepatic I/R and may play a significant role in the induction of the iNOS gene.


Subject(s)
Gene Expression , Ischemia/enzymology , Liver/blood supply , NF-kappa B/metabolism , Nitric Oxide Synthase/genetics , Reperfusion , Acetylcysteine/pharmacology , Animals , Antioxidants/pharmacology , Dimerization , Gene Expression/drug effects , Kinetics , Nitric Oxide Synthase/metabolism , Nitric Oxide Synthase Type II , Oxidative Stress , RNA, Messenger/metabolism , Rats , Rats, Sprague-Dawley
11.
Biochem Mol Biol Int ; 47(2): 251-4, 1999 Feb.
Article in English | MEDLINE | ID: mdl-10205670

ABSTRACT

The change of blood pressure and the induction of Na, K-ATPase alpha 1-subunit mRNA have been investigated in the renal cortex of aldosterone-treated hypertensive rat. The increase of blood pressure by aldosterone-treatment for 25 days was decreased by the treatment of amiloride or spironolactone. The level of Na, K-ATPase alpha 1-subunit mRNA of the renal cortex in aldosterone-treated rat was increased than that in the control, and its increase was repressed by treatment of spironolactone, but not altered by the treatment of amiloride. This result suggests that the increase of Na, K-ATPase alpha 1-subunit mRNA in the renal cortex of aldosterone-treated hypertensive rat may be related with the direct induction of Na, K-ATPase mRNA without the increase of Na-traffic through Na-channel.


Subject(s)
Aldosterone/pharmacology , Hypertension/chemically induced , Kidney/drug effects , RNA, Messenger/biosynthesis , Sodium-Potassium-Exchanging ATPase/genetics , Amiloride/pharmacology , Animals , Blood Pressure/drug effects , Gene Expression Regulation, Enzymologic/drug effects , Rats , Rats, Inbred Strains , Sodium Channels/metabolism , Sodium-Potassium-Exchanging ATPase/chemistry , Spironolactone/pharmacology , Time Factors
12.
Biochem Mol Biol Int ; 46(4): 667-72, 1998 Nov.
Article in English | MEDLINE | ID: mdl-9844726

ABSTRACT

The changes of Na,K-ATPase activity and its regulation have been investigated in the renal cortex of 1-clip-1-kidney hypertensive rat. Ouabain-sensitive Na,K-ATPase activity (Emax) and [3H]ouabain-binding site (Bmax) in the hypertensive rat were slightly increased than those in the control. The levels of Na,K-ATPase alpha 1- and beta 1-subunit mRNA of the renal cortex in hypertensive rat were more increased than those in the control. Their increases were repressed by actinomycin-D, but not altered or more increased by cycloheximide. These results suggest that the increase of Na,K-ATPase activities and ouabain binding sites in 1-clip-1-kidney hypertensive rat may be correlated with the increases of gene expression in transcription level and/or of mRNA stability of Na,K-ATPase.


Subject(s)
Hypertension, Renovascular/enzymology , Isoenzymes/metabolism , Kidney Cortex/enzymology , Sodium-Potassium-Exchanging ATPase/metabolism , Animals , Basement Membrane/enzymology , Isoenzymes/genetics , Ouabain/metabolism , RNA, Messenger/biosynthesis , RNA, Messenger/genetics , Rats , Sodium-Potassium-Exchanging ATPase/genetics
13.
Biochem Mol Biol Int ; 45(5): 879-85, 1998 Aug.
Article in English | MEDLINE | ID: mdl-9739452

ABSTRACT

The changes of Na,K-ATPase activity and its regulation have been investigated in the renal cortex and its basolateral membrane of aldosterone-induced hypertensive rat. Ouabain-sensitive Na,K-ATPase activity and [3H]ouabain-binding site (Bmax) in the hypertensive rat were significantly increased than those in the control. The levels of Na,K-ATPase alpha 1- and beta 1-subunit mRNA of the renal cortex in hypertensive rat were more increased than those in the control, and their increases were repressed by actinomycin-D. These results suggest that the increase of Na,K-ATPase activities and ouabain binding sites in aldosterone-induced hypertensive rat may be correlated with transcriptional regulation of Na,K-ATPase gene expression.


Subject(s)
Aldosterone/pharmacology , Gene Expression Regulation, Enzymologic , Hypertension/enzymology , Kidney Cortex/enzymology , Sodium-Potassium-Exchanging ATPase/metabolism , Animals , Binding Sites , Dactinomycin/pharmacology , Hypertension/chemically induced , Kidney Cortex/drug effects , Ouabain/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Rats , Sodium-Potassium-Exchanging ATPase/genetics , Transcription, Genetic/drug effects
14.
Biochemistry ; 37(14): 4804-14, 1998 Apr 07.
Article in English | MEDLINE | ID: mdl-9537997

ABSTRACT

The lobster skeletal muscle Ca2+ release channel, known also as the ryanodine receptor, is composed of four polypeptides of approximately 5000 amino acids each, like its mammalian counterparts. Clones encoding the carboxy-terminal region of the lobster ryanodine receptor were isolated from a lobster skeletal muscle cDNA library. Analysis of the deduced 1513 carboxy-terminal amino acid sequence suggests a cytoplasmic Ca2+ binding domain consisting of two EF-hand Ca2+ binding motifs (amino acid residues 594-656). The Ca2+ binding properties of this domain were assessed by preparing bacterial fusion proteins with sequences from the lobster Ca2+ binding domain and the corresponding sequences of the rabbit cardiac and skeletal muscle ryanodine receptors. The lobster skeletal muscle fusion protein bound 45Ca2+ in Ca2+ overlays, and bound two Ca2+ under equilibrium binding conditions with a Hill dissociation constant (KH) of 0.9 mM and coefficient (nH) of 1.4. Rabbit skeletal and cardiac fusion proteins bound two Ca2+ with KHs of 3.7 and 3.8 mM and nHs of 1.1 and 1.3, respectively. Similar to results previously reported for the mammalian RyRs, the lobster RyR was activated by micromolar Ca2+ and inhibited by millimolar Ca2+, as determined in single-channel and [3H]ryanodine binding measurements. These results suggest that the two EF-hand Ca2+ binding domain of the lobster Ca2+ release channel as well as the corresponding regions of the mammalian channels may play a role in Ca2+ inactivation of sarcoplasmic reticulum Ca2+ release.


Subject(s)
Calcium/metabolism , Muscle, Skeletal/metabolism , Ryanodine Receptor Calcium Release Channel/metabolism , Amino Acid Sequence , Animals , Binding Sites , Cloning, Molecular , Glutathione Transferase/genetics , Molecular Sequence Data , Nephropidae , Rabbits , Recombinant Fusion Proteins/chemistry , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , Ryanodine/metabolism , Ryanodine Receptor Calcium Release Channel/chemistry , Ryanodine Receptor Calcium Release Channel/genetics , Sequence Homology, Amino Acid
15.
J Biol Chem ; 267(22): 15893-901, 1992 Aug 05.
Article in English | MEDLINE | ID: mdl-1322408

ABSTRACT

The 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (Chaps)-solubilized ryanodine receptor (RyR) of lobster skeletal muscle has been isolated by rate density centrifugation as a 30 S protein complex. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of the purified 30 S receptor revealed a single high molecular weight protein band with a mobility intermediate between those of the mammalian skeletal and cardiac M(r) 565,000 RyR polypeptides. Immunoblot analysis showed no or only minimal cross-reactivity with the rabbit skeletal and canine cardiac RyR polypeptides. By immunofluorescence the lobster RyR was localized to the junctions of the A-I bands. Following planar lipid bilayer reconstitution of the purified 30 S lobster RyR, single channel K+ and Ca2+ currents were observed which were modified by ryanodine and optimally activated by millimolar concentrations of cis (cytoplasmic) Ca2+. Vesicle-45Ca2+ flux measurements also indicated an optimal activation of the lobster Ca2+ channel by millimolar Ca2+, whereas 45Ca2+ efflux from mammalian skeletal and cardiac muscle sarcoplasmic reticulum (SR) vesicles is optimally activated by micromolar Ca2+. Further, mammalian muscle SR Ca2+ release activity is modulated by Mg2+ and ATP, whereas neither ligand appreciably affected 45Ca2+ efflux from lobster SR vesicles. These results suggested that lobster and mammalian muscle express immunologically and functionally distinct SR Ca2+ release channel protein complexes.


Subject(s)
Calcium Channels/physiology , Calcium/metabolism , Muscles/physiology , Receptors, Cholinergic/physiology , Ryanodine/pharmacology , Animals , Fluorescent Antibody Technique , Immunoblotting , Kinetics , Mammals , Membrane Potentials/drug effects , Molecular Weight , Nephropidae , Receptors, Cholinergic/isolation & purification , Receptors, Cholinergic/metabolism , Ryanodine/metabolism , Ryanodine Receptor Calcium Release Channel
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