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PubMed1985

Size distribution of casein micelles during milk coagulation.

Electron microscopy was employed to study the size distribution and the surface to volume ratios of casein micelles in coagulum from raw milk, heated milk and milk enriched with calcium chloride before the heating process. The particles size distribution of milk protein was changed by heating resulting in an increase in the free subunits of smaller size and the surface to volume ratios. On the other hand the clotting time was prolonged. Depression in the clotting time and surface to volume ratios was occurred by adding calcium chloride to the milk before the heating process to retard the formation of complex between the whey protein and milk casein.

Animals↗
PubMed1995

Calcium-activated chloride fluxes in cultured NCL-SG3 sweat gland cells.

The dependence of chloride permeability of the human sweat gland cell line NCL-SG3 cell line on cytosolic free calcium ([Ca2+]i) was investigated. X-ray microanalysis, fura-2 fluorescence and patch clamp methodology were used. Carbachol and A23187 decreased cellular Cl and K for cells grown on permeable supports, but carbachol had no effect on cells grown on impermeable supports. In perforated patch experiments with impermeable supports, ATP and calcium ionophores increased the inward current (ic) whereas carbachol had no effect. ic was unaffected by cation channel blockers or removal of extracellular Na+ but was blocked by chloride channel blockers. Lowering bath Ca2+ decreased ic. On raising bath Ca2+ ic and [Ca2+]i responded with a transient rise which was not blocked by La3+ or D-600. La3+, but not D-600, blocked the entry of Mn2+. K(+)-depolarization and Bay-K-8644 had little effect on [Ca2+]i. The rise in [Ca2+]i may be mediated primarily via depletion operated Ca(2+)-channels. Irrespective of substrate NCL-SG3 cells have a chloride permeability which depends on [Ca2+]i.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1994

Quantitation of in vitro coronary artery calcium using ultrafast computed tomography.

Ultrafast computed tomography (UFCT) has the potential to quantify coronary hydroxyapatite (HAP). However, no definitive studies validating this technique are available. We constructed a human chest phantom model with coronary arteries represented by cylindrical holes containing: (1) calcium chloride solutions, (2) a block of HAP immersed in paraffin (without partial volume effect), and (3) HAP granules embedded in a gelatin matrix (with partial volume effect). We scanned this model to determine the relationship between measured CT number per voxel and density of the calcium per voxel. The relationships between CT number and concentration of calcium chloride was linear (r = 0.992 to 0.999). Using a commercially available standard bone mineral phantom, we were able to estimate the concentration of HAP to an accuracy from 94 to 97% when partial volume effects were absent. However, when partial volume effects were present, two methods of estimating HAP produced significant errors (1 to 384%, and 17 to 52%). We conclude that significant partial voluming errors degrade the accuracy of HAP quantitation and that further evaluation and corrections are needed before such quantitation is clinically applied.

Calcium Chloride↗
PubMed2003

Reciprocal interactions between calcium and chloride in rod photoreceptors.

This study used imaging and electrophysiological techniques in salamander retinal slices to correlate Ca2+ and Cl- levels in rods and thus test the hypothesis of a feedback interaction between Ca2+- and Ca2+-activated Cl- channels whereby Cl- efflux through Cl- channels can inhibit Ca2+ channels. Increasing [K+]o levels produced a concentration-dependent depolarization of rods accompanied by increases in [Ca2+]i measured with Fura-2. The voltage dependence of increases in [Ca2+]i was compared with the voltage dependence of the calcium current (ICa). [Cl-]i was measured with the dye, MEQ. Depolarization with high K+ to membrane potentials below -20 mV reduced [Cl-]i; larger depolarizations increased [Cl-]i. The Na/K/Cl cotransport inhibitor, bumetanide, shifted the apparent Cl- equilibrium potential (ECl) to more negative potentials, suggesting that this cotransporter helps establish a relatively depolarized ECl. MEQ fluorescence changes evoked by high K+ were inhibited by niflumic acid (0.1 mM), NPPB (2 microM), or replacement of Ca2+ with Ba2+, suggesting that depolarization-evoked Cl- changes result partly from stimulation of Ca2+-activated Cl- channels. Replacing >/=12 mM [Cl-]o with CH3SO4- produced a significant reduction in [Cl-]i. [Ca2+]i increases evoked by 20 or 50 mM K+ were also significantly inhibited by replacing >/=12 mM [Cl-]o with CH3SO4-. Thus modest depolarization can evoke increases in [Ca2+]i that lead to reductions in [Cl-]i, and conversely, reductions in [Cl-]i inhibit depolarization-evoked [Ca2+]i increases. These findings support the hypothesis that feedback interactions between Ca2+- and Ca2+-activated Cl- channels may contribute to the regulation of presynaptic Ca2+ currents involved in synaptic transmission from rod photoreceptors.

Ambystoma↗
PubMed1994

Effect of different antibiotics on efficiency of transformation of bacteria by electroporation.

We noted large differences in the transformation efficiency of Escherichia coli when different methods were used for transformation. To analyze these observations, the ampicillin and tetracycline resistance plasmid, pBR322, was transformed into HB101 and DH5 alpha E. coli using calcium chloride or electroporation, and the clones containing the plasmids were selected under various conditions. Electroporation yielded around 5 x 10(7) transformants per microgram of plasmid DNA when ampicillin was used for selection, but only 5 x 10(5) transformants per microgram when tetracycline was used. A calcium-chloride method of transformation showed no differences between the two antibiotics. The loss of efficiency of electroporation in the presence of tetracycline was also seen with three tetracycline-related antibiotics and could be blocked by chelating agents. It was also overcome by a 3-h preincubation of the bacteria before exposure to antibiotic. D-Cycloserine showed a selective effect on electroporated bacteria, but Polymyxin-B, chloramphenicol or phosphonomycin did not. The mechanism of inhibition by tetracycline-related antibiotics is not known, but the results show that the recovery of electroporated bacteria may be significantly decreased if these antibiotics are used.

Ampicillin↗
PubMed1986

[Comparative effects of adenosine and L-N-phenylisopropyladenosine (L-PIA) on the spontaneous contraction of the isolated atrium in the guinea-pig].

It has been found that adenosine produces a concentration-dependent decrease in both the isometric contraction and the atrial rate of the isolated, spontaneously beating atria of the guinea-pig. In the present experiments, it was of interest to study the effect of adenosine on the isometric contraction and the atrial rate in the presence of aminophylline, calcium chloride and verapamil in the organ bath. It was also of interest to compare the effects of adenosine and adenosine derivative. L-PIA on the isolated guinea-pig heart atria. The dose-response curves for both adenosine and L-PIA were shifted to the right in the presence of aminophylline (13 and 32 mumol l-1). The presence of verapamil (73 nmol l-1) in the organ bath potentiated the depressive actions of the both adenosine and L-PIA. Calcium chloride (1.8 mmol l-1) completely antagonized the negative inotropic action of both substances. Our results indicate a possible antagonism between adenosine, L-PIA and calcium, on the other hand, on the isolated, spontaneously beating guinea-pig atria. Also, our results strongly suggest competitive antagonism between adenosine, L-PIA and aminophylline at adenosine receptor sites.

Adenosine↗
PubMed1980

The effect of seed crystals on calcium oxalate nucleation.

Equimolar concentrations of calcium chloride and potassium oxalate were precipitated by a rapid mixing technique. The precipitated calcium oxalate particles were repeatedly counted at 15 min with a Coulter counter until reproducible total particle count and particle distribution curves were obtained. These values were compared with those found after the addition of various seed crystals and 10 per cent urine to the system. Calcium oxalate seed crystals markedly enhanced the nucleation rate of calcium oxalate (1), although only an estimated 16 per cent acted as effective nucleators. The addition of sodium acid urate crystals resulted in a small decrease in the number of calcium oxalate particles precipitated and fewer than 0.1 per cent of the crystals acted as effective nuclei. Seeds of agglomerated hydroxyapatite crystals also produced a small decrease in the number of calcium oxalate particles and fewer than 1 per cent of the seeds functioned as nucleators. The addition of 10 per cent urine to the system greatly increased the number of calcium oxalate particles produced although we are uncertain whether the urine provided effective nuclei or prevented particle aggregation. Our data indicate that, in a rapidly mixed system, neither sodium acid urate nor hydroxyapatite crystals are effective nucleators for the precipitation of calcium oxalate. The occurrence of epitaxial growth of calcium oxalate on these substances in urinary stones is therefore called into question.

Calcium Chloride↗
PubMed1990

Enhancement and stabilization of the production of glucoamylase by immobilized cells of Aureobasidium pullulans in a fluidized-bed reactor.

Glucoamylase production by Aureobasidium pullulans A-124 was compared in free-living cells, cells immobilized in calcium alginate gel beads aerated on a rotary shaker (agitation rate 150 rpm), and immobilized cells aerated in an air bubble column reactor. Fermentation conditions in the bioreactor were established for bead concentration, substrate (starch) concentration, calcium chloride addition to the fermentation medium, and rate of aeration. Production of glucoamylase was optimized at approximately 1.5 units of enzyme activity/ml medium in the bioreactor under the following conditions: aeration rate, 2.0 vol air per working volume of the bioreactor (280 ml) per minute; gel bead concentration, 30% of the working volume; substrate (starch) concentration, at 0.3% (w/v); addition of calcium chloride to the medium at a final concentration of 0.01 M. Productivity levels were stabilized through the equivalent of ten batches of medium with the original inoculum of immobilized beads.

Alginates↗
PubMed1999

Effect of the formulation on the in-vitro release of propranolol from gellan beads.

Gellan gum beads of propranolol hydrochloride, a hydrophilic model drug, were prepared by solubilising the drug in a dispersion of gellan gum and then dropping the dispersion into calcium chloride solution. The droplets formed gelled beads instantaneously by ionotropic gelation. Major formulation and process variables which might influence the preparation of the beads and the drug release from gellan gum beads were studied. Very high entrapment efficiencies were obtained (92%) after modifying the pH of both the gellan gum dispersion and the calcium chloride solution. The beads could be stored for 3 weeks in a wet or dried state without modification of the drug release. Oven-dried beads released the drug somewhat more slowly than the wet or freeze-dried beads. The drug release from oven-dried beads was slightly affected by the pH of the dissolution medium. Gellan gum could be a useful carrier for the encapsulation of fragile drugs and provides new opportunities in the field of bioencapsulation.

Calcium Chloride↗
PubMed2005

Effect of protein concentration, pH, lactose content and pasteurization on thermal gelation of acid caprine whey protein concentrates.

The influence of pH (4.5-6.5), sodium chloride content (125-375 mM), calcium chloride content (10-30 mM), protein concentration (70-90 g/l) and lactose content on the gel hardness of goat whey protein concentrate (GWPC) in relation to the origin of the acid whey (raw or pasteurized milk) was studied using a factorial design. Gels were obtained after heat treatment (90 degrees C, 30 min). Gel hardness was measured using texture analyser. Only protein concentration and pH were found to have a statistically significant effect on the gel hardness. An increase in the protein concentration resulted in an increase in the gel hardness. GWPC containing 800g/kg protein formed gels with a hardness maximum at the pHi, whereas GWPC containing 300 g/kg protein did not form true gels. Whey from pasteurized milk formed softer gels than whey from raw milk. A high lactose content (approximately 360 g/kg) also reduced the gelation performance of GWPC.

Animals↗
PubMed2004

Studies of gelation process investigated by fast field cycling relaxometry and dynamical rheology: the case of aqueous low methoxyl pectin solution.

The Fast Field Cycling Relaxometry and the dynamical rheology were applied to study the gelation process in aqueous low methoxyl pectin solution in the presence of divalent cations from the calcium chloride. The model-free approach to the analysis of 1H NMRD data was used to separate the information on the static and dynamic behaviour of the system provided by the dispersion profiles of the systems tested. Mechanical spectroscopy was applied as a complementary method to probe the network formation. The structural changes were most pronounced for the concentration of calcium chloride between 10 and 15 mM (the static parameter beta was found to vary from 0.936 x 10(7) to 1.27 x 10(7) 1/s2) revealing the sol-gel transition on visual inspection. The presence of the gel network was confirmed by the rheological measurements. All mechanical spectra exhibited the gel like character, and the solid like response was more evident at higher concentrations of calcium cations. The mean correlation time increased with increasing salt concentration, but remained unchanged for the concentrations above 15 mM. The dynamical changes were most significant at the phase transition from the sol to the gel state.

Calcium Chloride↗
PubMedDate not supplied

GABA activity in dispersed bovine pineal cells: effect on serotonin release and calcium and chloride uptake.

The presence of gamma-aminobutyric acid (GABA) and peripheral and central benzodiazepine receptors in the mammalian pineal gland prompted the examination of GABAergic transmission in dispersed bovine pineal cells. The effect of GABA on 3H-serotonin (5HT) release was examined in bovine pineal cells. GABA, by acting through GABA B receptor subtype, decreased 5HT release and by acting through GABA B, and presumably through GABA A receptor subtypes, inhibited depolarization-induced 45Ca2+ uptake in bovine pinealocytes. GABA, by acting on GABA B as well as on GABA A receptors, prevented the 5HT2- or 5HT1C-mediated stimulatory effect of serotonergic agonists on calcium uptake in pineal cells. GABA augmented 36Cl- uptake by bovine pineal cells. These results are interpreted to indicate that, by regulating the release of 5HT, GABA may modulate the synthesis and action of melatonin.

Analysis of Variance↗
PubMed2003

Human papillomavirus type 59 immortalized keratinocytes express late viral proteins and infectious virus after calcium stimulation.

Human papillomavirus type 59 (HPV 59) is an oncogenic type related to HPV 18. HPV 59 was recently propagated in the athymic mouse xenograft system. A continuous keratinocyte cell line infected with HPV 59 was created from a foreskin xenograft grown in an athymic mouse. Cells were cultured beyond passage 50. The cells were highly pleomorphic, containing numerous abnormally shaped nuclei and mitotic figures. HPV 59 sequences were detected in the cells by DNA in situ hybridization in a diffuse nuclear distribution. Southern blots were consistent with an episomal state of HPV 59 DNA at approximately 50 copies per cell. Analysis of the cells using a PCR/reverse blot strip assay, which amplifies a portion of the L1 open reading frame, was strongly positive. Differentiation of cells in monolayers was induced by growth in F medium containing 2 mM calcium chloride for 10 days. Cells were harvested as a single tissue-like sheet, and histologic analysis revealed a four-to-six cell-thick layer. Transcripts encoding involucrin, a cornified envelope protein, and the E1/E4 and E1/E4/L1 viral transcripts were detected after several days of growth in F medium containing 2 mM calcium chloride. The E1/E4 and L1 proteins were detected by immunohistochemical analysis, and virus particles were seen in electron micrographs in a subset of differentiated cells. An extract of differentiated cells was prepared by vigorous sonication and was used to infect foreskin fragments. These fragments were implanted into athymic mice. HPV 59 was detected in the foreskin xenografts removed 4 months later by DNA in situ hybridization and PCR/reverse blot assay. Thus, the complete viral growth cycle, including production on infectious virus, was demonstrated in the HPV 59 immortalized cells grown in a simple culture system.

Animals↗
PubMed2001

Left ventricular diastolic dysfunction during demand ischemia: rigor underlies increased stiffness without calcium-mediated tension. Amelioration by glycolytic substrate.

OBJECTIVES: The goal of this study was to determine the subcellular mechanism(s) underlying increased left ventricular (LV) diastolic chamber stiffness (DCS) during angina (demand ischemia). BACKGROUND: Increased DCS may result from increased diastolic myocyte calcium concentration and/or rigor. Therefore, we assessed the effects of direct alterations of both calcium-activated tension and high-energy phosphates on increased DCS. METHODS: Demand ischemia was reproduced in isolated, isovolumic, red-cell perfused rabbit hearts by imposing low-flow ischemia and pacing tachycardia. This resulted in increased DCS. Interventions were performed after LV end-diastolic pressure had increased approximately 7 mm Hg. Initially, to determine the effects of altered calcium concentration or myofilament calcium responsiveness, hearts received either: 1) 5 or 14 mmol/L calcium chloride; 2) 8 mmol/L egtazic acid; 3) 5 mmol/L butane-dione-monoxime (BDM); or 4) 50 mmol/L ammonium chloride (NH4Cl). Then, to assess the contribution of decreased high-energy phosphate supply, hearts received 5) glucose (25 mmol/L) and insulin (400 microU/ml). RESULTS: 1) Calcium chloride, 5 and 14 mmol/L, increased LV systolic pressure by 42% and 70%, respectively (p < 0.001), indicating increased calcium-activated tension, but did not further increase DCS, implying intact diastolic calcium resequestration. 2) Egtazic acid reduced LV systolic pressure by 30% (p < 0.001), indicating reduced intracellular calcium, but failed to reduce increased DCS. 3) Butane-dione-monoxime and NH4Cl chloride affected contractile function (i.e., a calcium-driven force) but did not alter increased DCS. 4) Glucose and insulin, which increase high-energy phosphates during ischemia, reduced increased DCS by 50% (p < 0.001). CONCLUSIONS: Increased DCS during demand ischemia was insensitive to maneuvers altering intracellular calcium concentration or myofilament calcium-responsiveness, that is, evidence against an etiology of calcium-activated tension. In contrast, increased glycolytic substrate ameliorated increased DCS, supporting a primary mechanism of rigor-bond formation.

Angina Pectoris↗
PubMed1990

Effects of calcium channel modulators on the proliferation of mouse spleen lymphocytes in vitro.

The effects of nimodipine (voltage-dependent calcium channel blocker), CGP 28392 and BAY K 8644 (novel dihydropyridine derivatives that are considered as calcium entry stimulators) on the spontaneous proliferation of mouse spleen lymphocytes were studied in vitro. [3H]-thymidine incorporation into DNA of lymphocytes was used as an sensitive index of the cell proliferation. It has been found that nimodipine (10(-4) M-10(-6) M) significantly inhibited the [3H]-thymidine uptake in a dose dependent fashion with ED50 value of 2.4 x 10(-5) M. Unexpectedly, CGP 28392 (10(-4) M-10(-7) M) acts as a calcium entry blocker and produces a strong inhibitory effect on lymphocyte proliferation (ED50-2 x 10(-5) M). BAY K 8644 at a high concentration (10(-4) M) also has an inhibitory effect but at a lower concentration (10(-6) M-10(-10) M) significantly increased [3H]-thymidine uptake and abolished the inhibitory effect of nimodipine. This effect of nimodipine was also reversed by 5 x 10(-3) M calcium chloride. These findings indicate that calcium channel modulators can regulate the proliferation of mouse spleen lymphocytes in vitro.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed2005

Cross-linking of dried paracetamol alginate granules Part 1. The effect of the cross-linking process variables.

This paper reports on the cross-linking of dried (<5% moisture) paracetamol alginate granules with calcium chloride solutions. The effect of calcium concentration, temperature of the treatment solution, stirring speed and time used during cross-linking of granules on water uptake by the granules during cross-linking and physical properties of the cross-linked and dried granules were studied. A full factorial study of these factors each at two levels was used (CaCl2.2H2O: 20, 100 mg/ml; temperature: 25, 45 degrees C; stirrer speed: 25, 240 rpm; time: 1.5 and 5.5 min) to treat dried stock granules (size: 0.8-1.0 mm) containing the model drug paracetamol and sodium alginate powder (1:1) which were prepared using conventional aqueous granulation under low shear. In addition to SEM and photomicrography, the physical properties studied were water uptake during cross-linking, yield, aggregation behaviour, moisture content, drug content, early stage drug release [over 10 s (R10) and the next 50 s (R50)] and calcium and sodium content of the unwashed cross-linked granules. Dry granules were successfully cross-linked. The treatment factors significantly affected most of the response variables. The variables most affected were water uptake (78-254%), drug entrapment (58-86%), early release (R10: 1.2-6.4% and R50: 3.0-12.2%), granule aggregation (0-70%), calcium (6.02-12.4%) and sodium content (1.2-6.44%). SEM photographs suggest that low calcium treated granules were less porous in nature compared to high calcium treated granules. Low shear drug alginate granules can be cross-linked in dried state. The properties of the cross-linked granules can be modified by altering the treatment process.

Acetaminophen↗
PubMed1976

Effects of acetylsalicylic acid, dipyridamole, and hydrocortisone on epinephrine-induced myocardial injury in dogs.

A reproducible model for producing diffuse myocardial injury (epinephrine infusion) has been developed to study the cardioprotective effects of agents or maneuvers which might alter the evolution of acute myocardial infarction. Infusions of epinephrine (4 mug per kilogram per minute for 6 hours) increased radiocalcium uptakes into intact myocardium and each of its subcellular components with the mitochondrial fraction showing the most consistent changes when compared to saline-infused control animals (4,957 vs. 827 counts per minute per gram of dried tissue or fraction). Myocardial concentrations of calcium also increased significantly (12.0 vs. 5.0 mg.per 100 Gm. of fat-free dry weight). Infusions of calcium chloride sufficient to raise serum calcium concentrations 2 mEq. per liter failed to increase calcium influx into the myocardial cell. Mitochondrial radiocalcium uptakes were significantly decreased in animals pretreated with acetylsalicylic acid or dipyridamole or when hydrocortisone was added to the epinephrine infusion (2,682,2,803, and 3,424 counts per minute per gram of dried fraction, respectively). Myocardial calcium concentrations also were decreased (11.2, 8.3, and 8.9 mg. per 100 Gm. of fat-free dry weight, respectively) in the three treatment groups, being significantly decreased only in the last two. Evidence of microscopic damage was graded as less severe in the three treatment groups. Acetylsalicylic acid, dipyridamole, and hydrocortisone all appear to have cardioprotective effects when tested in this model.

Acute Disease↗