scholarly journals Regional Imaging of Brain Tissue Calcium Ions Using Aequorin

1992 ◽  
Vol 12 (2) ◽  
pp. 306-310 ◽  
Author(s):  
Kenji Hashimoto ◽  
Haruhiko Kikuchi ◽  
Masatsune Ishikawa ◽  
Shuichi Kobayashi
Keyword(s):  
Linear Relationship ◽  
Spatial Resolution ◽  
Calcium Ions ◽  
Calcium Ion ◽  
High Spatial Resolution ◽  
Ion Concentration ◽  
Ion Distribution ◽  
Ion Concentrations ◽  
Tissue Calcium ◽  
Calcium Ion Concentration

To investigate regional changes in calcium ion concentrations, we developed a new histochemical method using aequorin, a calcium ion-sensitive photoprotein. In this method, reagent film containing aequorin was made and an unfixed slice of frozen brain 16 μm thick was placed on it. Tissue calcium ions permeated the reagent layer and the bioluminescence of aequorin-calcium ions was recorded photographically with high spatial resolution. There was a close linear relationship ( r = 0.903) between the optical density of the bioluminescent images and the logarithmic values of the tissue calcium ion concentration. Using this method, we could visualize the regional tissue calcium ion distribution in pathological states in rat brains.

Effect of Minerals on Casein Micelle Stability of Cows' Milk

2007 ◽  
Vol 74 (2) ◽  
pp. 167-173 ◽  
Author(s):  
Alexandros Tsioulpas ◽  
Michael J Lewis ◽  
Alistair S Grandison
Keyword(s):  
Linear Relationship ◽  
Calcium Ions ◽  
Calcium Ion ◽  
Ion Concentration ◽  
Free Calcium ◽  
Casein Micelle ◽  
Clotting Time ◽  
Rennet Coagulation ◽  
Calcium Ion Concentration ◽  
Ethanol Stability

The effects of minerals on casein micelle stability of individual cows' milk, throughout a complete lactation, were investigated. Calcium and calcium ions, magnesium, phosphorus, sodium, potassium and citrate contents were analysed, together with the following physical properties of milk; pH, ethanol stability, rennet clotting time and coagulum firmness. There was an inverse non-linear relationship between free calcium ion concentration and ethanol stability (ES; r=0·84). Rennet coagulation time showed a weaker relationship with free calcium ion concentration (r=0·44) but a stronger relationship with pH (r=0·66). In addition, samples containing higher amounts of free calcium ions produced a firmer gel. Citrate in natural samples acts as a stabilizing factor, as it slightly improves milk stability. Potassium, on the other hand, exhibited a negative correlation, but only with rennet clotting time (r=−0·52). Throughout lactation the average values were; free Ca2+ concentration 1·88 mM, pH 6·63, ES 83·2% and clotting time 13·6 min. The equilibrium relationship between pH and free Ca2+ concentration was investigated by adjusting milk pH from 5·9 to 7·1, using acid and alkali. There was a good inverse linear relationship between pH and log (free Ca2+) for individual milk samples, with a gradient of −0·62 and a standard deviation of 0·042.

scholarly journals ADENOSINE TRIPHOSPHATE-LINKED CONCENTRATION OF CALCIUM IONS IN A PARTICULATE FRACTION OF RABBIT MUSCLE

1962 ◽  
Vol 14 (3) ◽  
pp. 389-400 ◽  
Author(s):  
Setsuro Ebashi ◽  
Fritz Lipmann
Keyword(s):  
Skeletal Muscle ◽  
Endoplasmic Reticulum ◽  
Electron Micrographs ◽  
Calcium Ions ◽  
Calcium Ion ◽  
Membrane Fraction ◽  
Ion Concentration ◽  
Rabbit Muscle ◽  
Differential Centrifugation ◽  
Calcium Ion Concentration

ATPase and ATP-dependent calcium ion concentration was studied with a membrane fraction isolated from homogenized rabbit skeletal muscle by differential centrifugation. Electron micrographs of the fraction indicate that it consists mainly of resealed tubules and vesicles of the endoplasmic reticulum. The up-to-1400-fold concentration of calcium in this fraction might be explained by proposing the existence of an energy-requiring system for the transport of calcium ions into the tubules or vesicles.

Physiochemical Properties of Thermomycolase, the Thermostable, Extracellular, Serine Protease of the Fungus Malbranchea pulchella

1974 ◽  
Vol 52 (11) ◽  
pp. 981-990 ◽  
Author(s):  
Gerrit Voordouw ◽  
G. Maurice Gaucher ◽  
Rodney S. Roche
Keyword(s):  
Molecular Weight ◽  
Calcium Ion ◽  
Sodium Dodecyl ◽  
Sedimentation Coefficient ◽  
Ion Concentration ◽  
Sedimentation Equilibrium ◽  
Globular Structure ◽  
Ion Concentrations ◽  
Malbranchea Pulchella ◽  
Calcium Ion Concentration

The physicochemical properties of the extracellular protease of the fungus Malbranchea pulchella, for which we have adopted the name thermomycolase, were investigated. The molecular weight of diisopropylphosphorylthermomycolase was found to be 32 000–33 000 by sedimentation equilibrium and sodium dodecyl sulfate (SDS) gel electrophoresis. Its sedimentation coefficient (s020, w = 2.97 S), intrinsic viscosity ([η] = 3.0 cc/g), and frictional ratio (f/f0 = 1.09) characterize the enzyme as a typical globular protein. The circular dichroism spectrum of the protein is also consistent with its globular structure. Active thermomycolase autolyzes extensively, especially at low calcium ion concentrations, producing low molecular weight peptide material. In the presence of SDS, a different autolytic degradation is observed, resulting in much higher molecular weight polypeptide products (16 500, 12 500,11 000, 8 500). The results indicate that, in the presence of SDS, thermomycolase has three sites that are highly susceptible to autolysis. At calcium ion concentrations of 10−3 M and 10−2 M the enzyme undergoes a sharp thermal denaturation with transition temperatures at 69 °C and 75 °C, respectively, and with complete loss of enzyme activity. At 70 °C the enzyme appeared to be maximally thermostable at a calcium ion concentration of 10−2 M.

scholarly journals The membrane potential of human platelets

Blood ◽  
1983 ◽  
Vol 61 (1) ◽  
pp. 180-185
Author(s):  
LT Friedhoff ◽  
M Sonenberg
Keyword(s):  
Membrane Potential ◽  
Calcium Ion ◽  
Human Platelet ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
Ion Concentration ◽  
Extracellular Potassium ◽  
Ion Concentrations ◽  
Calcium Ion Concentration ◽  
Extracellular Sodium

The membrane potential of the human platelet was investigated using the membrane potential probes 3,3′-dipropyl-2,2′-thiadicarbocyanine iodide and tritiated triphenylmethylphosphonium bromide. The membrane potential in physiologic buffer was estimated to be 52–60 mV inside negative. The membrane was depolarized when extracellular potassium or hydrogen ion concentrations were increased. Changes in extracellular sodium, chloride, or calcium ion concentration had no measurable effect on membrane potential. Elevated extracellular potassium has been shown to increase platelet sensitivity to the aggregating agent, adenosine diphosphate. Our results show that changes in extracellular ion concentrations that depolarize platelets increase platelet sensitivity to aggregating agents. These results suggest that membrane potential changes may play a role in modulating the response of platelets to aggregating agents.

scholarly journals The membrane potential of human platelets

Blood ◽  
1983 ◽  
Vol 61 (1) ◽  
pp. 180-185 ◽  
Author(s):  
LT Friedhoff ◽  
M Sonenberg
Keyword(s):  
Membrane Potential ◽  
Calcium Ion ◽  
Human Platelet ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
Ion Concentration ◽  
Extracellular Potassium ◽  
Ion Concentrations ◽  
Calcium Ion Concentration ◽  
Extracellular Sodium

Abstract The membrane potential of the human platelet was investigated using the membrane potential probes 3,3′-dipropyl-2,2′-thiadicarbocyanine iodide and tritiated triphenylmethylphosphonium bromide. The membrane potential in physiologic buffer was estimated to be 52–60 mV inside negative. The membrane was depolarized when extracellular potassium or hydrogen ion concentrations were increased. Changes in extracellular sodium, chloride, or calcium ion concentration had no measurable effect on membrane potential. Elevated extracellular potassium has been shown to increase platelet sensitivity to the aggregating agent, adenosine diphosphate. Our results show that changes in extracellular ion concentrations that depolarize platelets increase platelet sensitivity to aggregating agents. These results suggest that membrane potential changes may play a role in modulating the response of platelets to aggregating agents.

The Sensitivity Shift Due to Light Adaptation Depending on the Extracellular Calcium Ion Concentration in Limulus Ventral Nerve Photoreceptor

1984 ◽  
Vol 39 (6) ◽  
pp. 662-679 ◽  
Author(s):  
H. Stieve ◽  
M. Bruns ◽  
H. Gaube
Keyword(s):  
Calcium Ion ◽  
Light Adaptation ◽  
Light Response ◽  
Ion Concentration ◽  
Ion Concentrations ◽  
Intracellular Ca ◽  
Calcium Effect ◽  
Calcium Ion Concentration ◽  
Additional Reduction ◽  
Ventral Nerve Photoreceptor

Receptor potentials of Limulus ventral photoreceptors were recorded in two defined states of moderate light- and considerable dark adaptation (LA, DA) by a repeated stimulus sequence consisting of a conditioning 2 s illumination (white light, response saturating intensity) followed by two 10 ms test flashes at fixed intervals evoking LA and DA responses (intensity varied from threshold to saturation of response amplitude). The half saturating intensity I50 was determined from response height vs log stimulus intensity curves for LA and DA, while the photoreceptor was superfused either by reference saline (physiological ion concentrations, including 10 mmol/l Ca2+) or by test salines in which the [Ca2+] was varied between 40 μmol/l and 100 mmol/l. The sensitivity of the dark-adapted receptor does not significantly depend on the [Ca2+]ex, but the sensitivity shift due to LA (measured by /50) is reduced when the [Ca2+]ex is lowered, and augmented when the [Ca2+]ex is increased. Additional reduction of the [Na2+]ex from 463 mmol/l to 46 mmol/l or increase of the [Mg2+]ex from 50 mmol/l to 100 mmol/l does not counteract the effect of lowered [Ca2+]ex on LA. The results confirm the assumption that a transient increase of the intracellular [Ca2+] supplied from extracellular sources during the light response is the main cause for LA This calcium effect on light adaptation is neither characterized by a calcium/sodium antagonism, nor mimicked by magnesium, in contrast to the calcium effect on the gating of the light-activated ion channels.

THE EFFECT OF INTRAVENOUSLY INJECTED CITRATE ON THE SERUM IONIZED CALCIUM IN THE RABBIT

1951 ◽  
Vol 29 (5) ◽  
pp. 245-254
Author(s):  
Murray Saffran ◽  
Orville F. Denstedt
Keyword(s):  
Calcium Ions ◽  
Calcium Ion ◽  
Complete Recovery ◽  
The Body ◽  
Ion Concentration ◽  
Frog Heart ◽  
Heart Preparation ◽  
Serum Ionized Calcium ◽  
Concentrated Solution ◽  
Calcium Ion Concentration

The effect of intravenously injected citrate solution, in various amounts and at different rates of administration, on the calcium ion concentration of the plasma was studied in the rabbit. The concentration of calcium ions was measured by means of the frog heart preparation. The rabbit is capable of rapidly clearing and disposing of large amounts of citrate. No effect on the calcium ion concentration of the blood could be demonstrated except when a concentrated solution of citrate was injected sufficiently rapidly to produce convulsions. Even under these conditions the calcium ion concentration in the blood was rapidly restored and usually a complete recovery was made within five minutes. Citrate is readily utilizable in the body.

Desensitization to chemical and food sensitivities by low-dose immunotherapy ascertained by provocation neutralization is associated with reduced influx of calcium ions into lymphocytes

2017 ◽  
Vol 14 (2) ◽  
Author(s):  
Basant K. Puri ◽  
John McLaren Howard ◽  
Jean A. Monro
Keyword(s):  
Cell Signaling ◽  
Intracellular Calcium ◽  
Calcium Ions ◽  
Calcium Ion ◽  
Low Dose ◽  
Immune Cell ◽  
Ion Concentration ◽  
Gas Sensitivity ◽  
Allergen Specific Immunotherapy ◽  
Calcium Ion Concentration

AbstractBackgroundFood and chemical sensitivities have detrimental effects on health and the quality of life. The natural course of such sensitivities can potentially be altered through various types of allergen-specific immunotherapy, including low-dose immunotherapy. The molecular mechanism by which low-dose immunotherapy causes desensitization has not thus far been elucidated. While resting lymphocytes maintain a low cytosolic calcium ion concentration, antigen receptor signaling results in calcium ion influx, predominantly via store-operated calcium channels. We therefore hypothesized that desensitization by low-dose immunotherapy is associated with reduced influx of calcium ions into lymphocytes. The aim of this study was to test this hypothesis.MethodsIntracellular lymphocytic calcium ion concentrations were assayed in a total of 47 patients, following incubation with picogram amounts of the test allergens, using a cell-permeable calcium-sensing ratiometric fluorescent dye and fluorescence spectroscopy, both at baseline and following successful provocation neutralization treatment with low-dose immunotherapy.ResultsLow-dose immunotherapy was associated with a reduction in lymphocytic intracellular calcium ion concentration following treatment of: 23 % for metabisulfite sensitivity (p<0.0004); 12 % for salicylate sensitivity (p<0.01); 23 % for benzoate sensitivity (p<0.01); 30 % for formaldehyde sensitivity (p<0.0001); 16 % for sensitivity to petrol exhaust (p<0.003); 16 % for natural gas sensitivity (p<0.001); 13 % for nickel sensitivity (p<0.05); 30 % for sensitivity to organophosphates (p<0.01); and 24 % for sensitivity to nitrosamines (p<0.05).ConclusionsLow-dose immunotherapy may affect baseline levels of intracellular calcium in lymphocytes, supporting the premise that allergens affect cell signaling in immune cells and provocation neutralization immunotherapy helps to promote more normal immune cell signaling.

scholarly journals Calcium-induced reorganization of desmosomal components in cultured human keratinocytes.

1984 ◽  
Vol 99 (6) ◽  
pp. 2211-2215 ◽  
Author(s):  
F M Watt ◽  
D L Mattey ◽  
D R Garrod
Keyword(s):  
Calcium Ions ◽  
Calcium Ion ◽  
Culture Medium ◽  
Human Keratinocytes ◽  
Preliminary Evidence ◽  
Ion Concentration ◽  
Intercellular Contact ◽  
Keratin Filaments ◽  
Entire Cell ◽  
Calcium Ion Concentration

We used antibodies raised against individual desmosomal components to study calcium-induced desmosome formation in human keratinocytes. When keratinocytes are forced to grow as a monolayer by reducing the level of calcium ions in the culture medium, there is little contact between adjacent cells. Raising the level of calcium ions rapidly induces desmosome formation, and stratification occurs within 24 h. We found that before addition of calcium the 115,000- and 100,000-mol-wt core glycoproteins were distributed over the entire cell surface, whereas the plaque proteins (205,000 and 230,000 mol wt), the 82,000- and 86,000-mol-wt proteins, and the 150,000-mol-wt glycoprotein were located throughout the cytoplasm. 15 min after increasing the calcium ion concentration, all of these molecules appeared at the cell margins. The intensity of peripheral staining increased over the next 2 h and during this time the distribution of keratin filaments changed from predominantly perinuclear to extend throughout the cytoplasm. Keratinocytes could be dissociated with EDTA for up to 2 h after exposure to calcium. After 3 h of exposure to calcium the cells were no longer susceptible to EDTA dissociation and staining for desmosomal plaque antigens persisted in regions of intercellular contact. Desmosomal staining in stratified cultures became greatly reduced within 24 h of lowering the calcium ion concentration again. We have preliminary evidence that stratification occurs by breakdown of desmosomes at lateral surfaces and reformation at surfaces of contact between basal and suprabasal cells, rather than by rearrangement of existing desmosomes. Involucrin-positive cells in the monolayer appeared to contain more 205,000- and 230,000-mol-wt proteins free in the cytoplasm than involucrin-negative cells.

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