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26 records – page 1 of 3.

Activation of skinned muscle fibres from the Norway lobster Nephrops norvegicus L. by manganese ions.

https://arctichealth.org/en/permalink/ahliterature46326
Source
J Muscle Res Cell Motil. 1998 Jun;19(5):537-48
Publication Type
Article
Date
Jun-1998
Author
J M Holmes
K. Hilber
S. Galler
D M Neil
Author Affiliation
Division of Environmental and Evolutionary Biology, University of Glasgow, UK.
Source
J Muscle Res Cell Motil. 1998 Jun;19(5):537-48
Date
Jun-1998
Language
English
Publication Type
Article
Keywords
Adenosine Triphosphate - pharmacology
Animals
Calcium - pharmacology
Comparative Study
Manganese - pharmacokinetics - pharmacology
Muscle Contraction - drug effects
Muscle Fibers, Slow-Twitch - drug effects - physiology
Nephropidae
Research Support, Non-U.S. Gov't
Abstract
Effects of Mn2+ and Ca2+ on the mechanical properties of glycerinated myofibrillar bundles originating from slow S1 type muscle fibres of superficial flexor muscles of the lobster Nephrops norvegicus were investigated. Mn2+ (5-20 microM) activated the preparations in a dose-dependent manner. The sensitivity of myofibrillar force generation for Mn2+ was around 30 times lower than that for Ca2+. The maximal tension produced under Mn2+ activation was about 75% of that under Ca2+ activation. At higher free Mn2+ concentrations (>2 mM), the steady-state force decreased; it was completely abolished at 30 mM free Mn2+. These high Mn2+ solutions were accompanied by changed in MgATP and MnATP concentrations, and in the ionic strength. Control experiments have shown that none of these parameters seemed fo account fully for the observed force depression in high Mn2+ solutions. It is likely that direct effects of Mn2+ such as a change of the myofilament surface charges are responsible. The maximal unloaded shortening velocity of the myofibrillar preparations was shown to be similar under maximal Mn2+ and Ca2+ activation. Conversely, the kinetics of stretch-induced delayed force increase were about two to three times faster under Mn2+ activation. These results suggest that certain steps of the cross-bridge cycle depend on the ion species bound to the regulatory proteins.
PubMed ID
9682140 View in PubMed
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[An increased sensitivity of the mitochondrial permeability transition pore to calcium in the heart of rats with chronic deficiency of nigrostriatal dopamine]

https://arctichealth.org/en/permalink/ahliterature98284
Source
Fiziol Zh. 2009;55(5):3-8
Publication Type
Article
Date
2009
Author
S A Talanov
S V Timoshchuk
O V Rudyk
V F Sahach
Source
Fiziol Zh. 2009;55(5):3-8
Date
2009
Language
Ukrainian
Publication Type
Article
Keywords
Animals
Calcium - pharmacology - physiology
Chronic Disease
Corpus Striatum - metabolism
Dopamine - deficiency
Dose-Response Relationship, Drug
Heart - drug effects - physiology
Heart Conduction System - drug effects - physiology
Male
Melatonin - pharmacology
Mitochondria, Heart - drug effects - metabolism - physiology
Mitochondrial Membrane Transport Proteins - metabolism
Mitochondrial Swelling - drug effects
Parkinsonian Disorders - metabolism
Rats
Rats, Wistar
Substantia Nigra - metabolism
Abstract
We studied the sensitivity of mitochondrial permeability transition pore (MPTP) opening to natural inductors--Ca2+ ions in the rat heart mitochondria with chronic deficiency of nigrostriatal dopamine caused by an injection of selective neurotoxin 6-hydroxidofamine in an ascending lateral bundle of the forebrain. MPTP-opening was determined specrophotometrically (lamda=520 nm) by a decrease in an optical density resulting from mitochondrial swelling. It has been shown that the rat heart mitochondria with chronic deficiency of nigrostriatal dopamine are more sensitive to Ca2+ in its physiological concentration (10(-7) mol/l) and overload (10(-6) - 10(-4) mol/l) in comparison to control animals. Thus, obtained results lead to a conclusion that an increased sensitivity of the mitochondrial permeability transition pore to calcium and mitochondrial membrane permeability may be one of the causes previously reported of disturbance in contractile function of the rat heart with chronic deficiency of nigrostriatal dopamine.
PubMed ID
20095378 View in PubMed
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[ATPase activity and fluorescence of myometrial actomyosin in experimental uterine inertia]

https://arctichealth.org/en/permalink/ahliterature66134
Source
Ukr Biokhim Zh. 1977 Mar-Apr;49(2):83-7
Publication Type
Article
Author
V L Zima
L A Sushko
G K Stepankovskaia
M D Kurskii
Source
Ukr Biokhim Zh. 1977 Mar-Apr;49(2):83-7
Language
Ukrainian
Publication Type
Article
Keywords
Actomyosin - metabolism
Adenosinetriphosphatase - metabolism
Animals
Calcium - pharmacology
English Abstract
Female
Histocytochemistry
Hydrogen-Ion Concentration
Magnesium - pharmacology
Myometrium - metabolism
Pregnancy
Rabbits
Spectrophotometry, Ultraviolet
Temperature
Uterine Inertia - enzymology - metabolism
Uterus - metabolism
Abstract
A comparative study was performed for actomyosin complexes of the female rabbit myometrium in the state of labour (actomyosin of the control) and secondary uterine inertia (actomyosin of the model). Under the secondary uterine inertia the activity of actomyosin Ca2+- and Mg2+-ATPase decreases. When pH of the medium changes, ATPase of control actomyosin has two peaks of the activity: at rH 6.0 and pH 9.0, that of the model at pH 6.0. Actomyosin of the model and control differs by a degree and rate of superprecipitation, thermal stability and structure. It is supposed that the structural changes in actomyosin under the secondary uterine inertia occur due to accumulation of the metabolism products, the level of which with this pathology is beyond the limits of the adaptation potentialities of the organism.
PubMed ID
17209 View in PubMed
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Calcium addition at the Hubbard Brook Experimental Forest increases sugar storage, antioxidant activity and cold tolerance in native red spruce (Picea rubens).

https://arctichealth.org/en/permalink/ahliterature93373
Source
Tree Physiol. 2008 Jun;28(6):855-62
Publication Type
Article
Date
Jun-2008
Author
Halman Joshua M
Schaberg Paul G
Hawley Gary J
Eagar Christopher
Author Affiliation
Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, VT 05405, USA. jhalman@uvm.edu
Source
Tree Physiol. 2008 Jun;28(6):855-62
Date
Jun-2008
Language
English
Publication Type
Article
Keywords
Antioxidants - metabolism
Calcium - pharmacology
Carbohydrates - physiology
Cold Climate
Cold Temperature
Fertilizers
Picea - drug effects - physiology
Plant Leaves - drug effects - physiology
Seasons
Abstract
In fall (November 2005) and winter (February 2006), we collected current-year foliage of native red spruce (Picea rubens Sarg.) growing in a reference watershed and in a watershed treated in 1999 with wollastonite (CaSiO(3), a slow-release calcium source) to simulate preindustrial soil calcium concentrations (Ca-addition watershed) at the Hubbard Brook Experimental Forest (Thornton, NH). We analyzed nutrition, soluble sugar concentrations, ascorbate peroxidase (APX) activity and cold tolerance, to evaluate the basis of recent (2003) differences between watersheds in red spruce foliar winter injury. Foliar Ca and total sugar concentrations were significantly higher in trees in the Ca-addition watershed than in trees in the reference watershed during both fall (P=0.037 and 0.035, respectively) and winter (P=0.055 and 0.036, respectively). The Ca-addition treatment significantly increased foliar fructose and glucose concentrations in November (P=0.013 and 0.007, respectively) and foliar sucrose concentrations in winter (P=0.040). Foliar APX activity was similar in trees in both watersheds during fall (P=0.28), but higher in trees in the Ca-addition watershed during winter (P=0.063). Cold tolerance of foliage was significantly greater in trees in the Ca-addition watershed than in trees in the reference watershed (P
PubMed ID
18381266 View in PubMed
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Calcium-calmodulin kinase II is the common factor in calcium-dependent cardiac expression and secretion of A- and B-type natriuretic peptides.

https://arctichealth.org/en/permalink/ahliterature78613
Source
Endocrinology. 2007 Jun;148(6):2815-20
Publication Type
Article
Date
Jun-2007
Author
Ronkainen Jarkko J
Vuolteenaho Olli
Tavi Pasi
Author Affiliation
University of Oulu, Department of Physiology and Biocenter Oulu, University of Oulu, 90014 Oulu, Finland.
Source
Endocrinology. 2007 Jun;148(6):2815-20
Date
Jun-2007
Language
English
Publication Type
Article
Keywords
Animals
Animals, Newborn
Atrial Natriuretic Factor - genetics - metabolism - secretion
Benzylamines - pharmacology
Ca(2+)-Calmodulin Dependent Protein Kinase - genetics - metabolism - physiology
Calcium - pharmacology
Cells, Cultured
Gene Expression Regulation - drug effects
Male
Myocytes, Cardiac - drug effects - metabolism
Natriuretic Peptide, Brain - genetics - metabolism - secretion
Rats
Rats, Sprague-Dawley
Sulfonamides - pharmacology
Abstract
Peptides derived from the precursor of A- and B-type natriuretic peptides (ANP and BNP) are powerful clinical markers of cardiac hypertrophy and dysfunction. It is known that many stimuli affecting the intracellular calcium concentration also induce ANP and BNP secretion. It was our intention to study the mechanisms by which calcium regulates the secretion of ANP and BNP. The effects of pacing and calcium-calmodulin kinase II activity on natriuretic peptide secretion were studied in isolated perfused rat atria and cultured rat neonatal cardiomyocytes. In isolated rat atrium pacing induced an increase in diastolic, systolic, and averaged intracellular free calcium concentration and a frequency-dependent increase in the secretion of both ANP and BNP. The molar ratio of the secreted natriuretic peptides (ANP to BNP) remained nearly constant ( approximately 1000) at all the pacing frequencies tested (1, 3, 6, and 8 Hz). Calmodulin kinase II inhibitor KN-93 (3 mum) did not affect intracellular free calcium concentration but showed a frequency-dependent inhibitory effect on ANP and BNP secretion without a change in ANP to BNP ratio. In the neonatal cardiomyocytes, KN-93 (3 mum) suppressed the secretion and gene expression of both ANP and BNP. Overexpression of constitutively active (T286D) or nuclear (delta(B)) calcium-calmodulin kinase II induced an increase in ANP and BNP gene expression. The results indicate that the calcium-dependent secretion and gene expression of A- and B-type natriuretic peptides are similarly regulated by calmodulin kinase II-dependent mechanisms. This is a plausible mechanism contributing to exercise-induced natriuretic peptide secretion and the augmented secretion in heart dysfunction due to impaired calcium handling.
PubMed ID
17332063 View in PubMed
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Coaggregation between Actinomyces viscosus with Streptococcus pyogenes and Streptococcus agalactiae.

https://arctichealth.org/en/permalink/ahliterature236837
Source
Microbiologica. 1986 Jul;9(3):393-8
Publication Type
Article
Date
Jul-1986
Author
G. Chisari
M R Gismondo
Source
Microbiologica. 1986 Jul;9(3):393-8
Date
Jul-1986
Language
English
Publication Type
Article
Keywords
Actinomyces - physiology
Calcium - pharmacology
Culture Media
Hot Temperature
Humans
Hydrogen-Ion Concentration
Mouth - microbiology
Spectrophotometry
Streptococcus agalactiae - physiology
Streptococcus pyogenes - physiology
Abstract
Interbacterial coaggregation between Actinomyces viscosus indigenous to the human mouth and Streptococcus pyogenes and Streptococcus agalactiae was studied. Fifteen of twenty-six strains of Streptococcus pyogenes and thirteen of thirty-one Streptococcus agalactiae showed a coaggregation with Actinomyces viscosus strain. The results show that the coaggregation mechanism required calcium and was dependent on pH. Some coaggregations were inhibited by 0.06 M. lactose and by 1 M. NaCl.
PubMed ID
3528763 View in PubMed
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[Denaturation stabilization of alpha-amylase from Aspergillus oryzae]

https://arctichealth.org/en/permalink/ahliterature13264
Source
Ukr Biokhim Zh. 1975 Jul-Aug;47(4):453-7
Publication Type
Article
Author
O S Tsyperovych
I P Halych
L O Kloesnyk
H H Artyukh
Source
Ukr Biokhim Zh. 1975 Jul-Aug;47(4):453-7
Language
Ukrainian
Publication Type
Article
Keywords
Amylases - isolation & purification - metabolism
Aspergillus - enzymology
Aspergillus oryzae - enzymology
Binding Sites
Calcium - pharmacology
Drug Stability
English Abstract
Heat
Kinetics
Protein Binding
Protein Denaturation
Urea - pharmacology
Abstract
Denaturation of alpha-amylase from Aspergillus oryzae was studied under the effect of heating urea and some other denaturating agents. Inhibition in the enzyme denaturation, deviation from the first order equation and, consequently, establishment of the false equilibrium in the system are shown. The values are calculated for the reaction rate constants of alpha-amylase denaturation under the effect to heat (40 degrees C) and urea. A method is developed for isolating native amylase stabilized by heating at 40 degrees C during the period of inactivation slowing down and preservation to the 50-70% activity in the system. It is shown that in the presence of calcium ions the stability of the isolated native enzyme is 13.0 +/- 2.5% hihger on the average to heating up to 40 degrees C, 28.4 %/- 7.2% higher - to the effect of 5.5 M urea and 18.4 +/- 3.6% higher - to 18% alcohol.
PubMed ID
1209773 View in PubMed
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Development of a biotic ligand model to predict the acute toxicity of cadmium to Daphnia pulex.

https://arctichealth.org/en/permalink/ahliterature97876
Source
Aquat Toxicol. 2010 Jun 1;98(1):1-7
Publication Type
Article
Date
Jun-1-2010
Author
Matthew Clifford
James C McGeer
Author Affiliation
Department of Biology, Wilfrid Laurier University, Waterloo, ON N2L 3C5, Canada.
Source
Aquat Toxicol. 2010 Jun 1;98(1):1-7
Date
Jun-1-2010
Language
English
Publication Type
Article
Keywords
Animals
Cadmium - toxicity
Calcium - pharmacology
Daphnia - drug effects
Lethal Dose 50
Models, Biological
Water Pollutants, Chemical - toxicity
Abstract
The goal of this study was to develop a biotic ligand model (BLM) to predict the acute toxicity of cadmium to Daphnia pulex. Organisms were cultured in moderately soft water and standard 48h acute toxicity tests were used to determine EC50s in various water chemistries where the effects of Ca(2+), Na(+), Mg(2+), Cl(-), K(+), pH, and two sources of natural organic matter (Suwannee River and Nordic Reservoir) were evaluated. Overall, toxicity responses were consistent with the free-ion activity model and the principles inherent in the BLM. Increases in Ca(2+) resulted in higher EC50s, indicating that Cd(2+) competes with Ca(2+) for uptake at the biotic ligand. Similar cation competition effects were observed when Mg(2+) was varied but with a less pronounced protective effect relative to Ca(2+). Changes in Na(+) and K(+) concentrations had no significant effect on Cd toxicity. EC50 values did not change significantly when pH was adjusted over a range from 8.0 to 6.1. Additions of natural organic matter resulted in elevated dissolved organic carbon (DOC) concentrations that significantly reduced Cd bioavailability via complexation of Cd(2+). An existing biotic ligand model (HydroQual BLM ver 2.2.3) was tested for its ability to predict acute Cd toxicity to D. pulex. Once the BLM was adjusted for the relatively sensitivity of D. pulex the protective effects of Ca and DOC could be predicted reasonably well but other test chemistries did not match with measured EC50s. Binding constants derived from the test results (logK(CaBL) of 4.1, logK(MgBL) of 3.7, logK(HBL) of 6.1 and logK(CdBL) of 7.0) were used to develop a modified BLM for the effects of Cd on D. pulex that accounted for the moderating effect of Ca and Mg on acute toxicity but overestimated the protective effect of DOC.
PubMed ID
20189256 View in PubMed
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The effect of extracellular calcium concentration on calcium-mediated cell signaling in NF1 tumor suppressor-deficient keratinocytes.

https://arctichealth.org/en/permalink/ahliterature9280
Source
Arch Dermatol Res. 2005 Apr;296(10):465-72
Publication Type
Article
Date
Apr-2005
Author
Timo Korkiamäki
Heli Ylä-Outinen
Pekka Leinonen
Jussi Koivunen
Juha Peltonen
Author Affiliation
Department of Anatomy and Cell Biology, University of Oulu, PB 5000, 90014, Finland. tkorkiam@paju.oulu.fi
Source
Arch Dermatol Res. 2005 Apr;296(10):465-72
Date
Apr-2005
Language
English
Publication Type
Article
Keywords
Adult
Calcium - pharmacology - physiology
Calcium Signaling - genetics - physiology
Cells, Cultured
Enzyme Inhibitors - pharmacology
Gap Junctions - physiology
Genes, Neurofibromatosis 1 - physiology
Heptanol - pharmacology
Humans
Keratinocytes - physiology
Middle Aged
Research Support, Non-U.S. Gov't
Thapsigargin - pharmacology
Abstract
Capacitative calcium entry and calcium wave propagation were studied in keratinocytes from healthy volunteers and patients with type 1 neurofibromatosis (NF1) in calcium-depleted and in low calcium culture medium. In previous studies, we found evidence that mutations of the NF1 tumor suppressor gene can lead to altered calcium-mediated cell signaling in keratinocytes cultured in the presence of a high extracellular calcium concentration. The present study demonstrated that the differences between normal and NF1 keratinocytes were dependent on extracellular calcium concentration. Specifically, when keratinocytes were exposed to thapsigargin under calcium-depleted culture conditions the subsequent increase in free intracellular calcium concentration was moderate in NF1 keratinocytes compared to controls. The finding indicates lowered endoplasmic calcium stores in NF1 which may also in part explain the reduced activation signal for capacitative calcium influx and the wound-induced intracellular Ca2+ transient observed in NF1 keratinocytes maintained in culture medium containing 0.05 mM calcium. The differences between control and NF1 keratinocytes were most pronounced when the cells were cultured in the presence of a high (1.8 mM) calcium concentration. Since elevated extracellular calcium levels induce keratinocytes to form cellular contacts and lead to terminal differentiation, markedly aberrant responses of NF1 keratinocytes in the presence of a high calcium concentration may help to explain previous findings on impaired formation of cellular junctions and differentiation in NF1 deficient cells.
PubMed ID
15735964 View in PubMed
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26 records – page 1 of 3.