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The effect of chemical agents on the turnover of the bound phosphate associated with the sodium-and-potassium ion-stimulated adenosine triphosphatase in ox brain microsomes.

1. The effect of chemical agents on the turnover of the Na(+)-dependent bound phosphate and the simultaneous Na(+)-dependent hydrolysis of ATP by a membrane preparation from ox brain was studied at an ATP/protein ratio of 12.5pmol/mug. 2. The agents were added immediately after phosphorylation of the preparation in a medium containing 50mm-sodium chloride and 2.5mum-[gamma-(32)P]ATP. 3. Concentrations of sodium chloride above 150mm, calcium chloride to 20mm and suramin to 1.4mm inhibited both phosphorylation and dephosphorylation and concomitantly slowed ATP hydrolysis. At 125mm-sodium chloride dephosphorylation and hydrolysis were slightly slowed without affecting phosphorylation. 4. Ethanol to 1.6m concentration inhibited dephosphorylation without affecting phosphorylation; the bound phosphate was increased and ATP hydrolysis slowed. 5. Ouabain to 4mm concentration partially inhibited ATP hydrolysis and caused a transient (1-2s) rise in bound phosphate followed by a rapid fall to a lower plateau value, which eventually declined to zero by the time ATP hydrolysis was complete. 6. Of the detergents examined Lubrol W, Triton X-100 and sodium deoxycholate had no significant effect on turnover. Sodium dodecyl sulphate and sodium decyl sulphate to 3.5mm and 20mm respectively completely inhibited turnover and ATP hydrolysis and stabilized the bound phosphate.

Adenosine Triphosphatases↗

Heat resistance of Bacillus stearothermophilus spores in alginate-mushroom puree mixture.

Thermal resistance of Bacillus stearothermophilus spores has been established inoculating spores in alginate-mushroom puree mixture (ungelled) and in alginate-mushroom puree mixture set in calcium chloride (gelled). Data are compared with those obtained suspending the spores in distilled water, mushroom extract and in calcium chloride. Results indicated that, in general, D values obtained in gelled mixture were higher than D values obtained in distilled water, mushroom extract or in ungelled mixture, while the D value in the ungelled mixture was similar to that obtained in distilled water. D121 value in gelled mixture was close to that obtained in 2% (w/v) calcium chloride.

Alginates↗

Release of proteins from the surface of bovine central nervous system myelin by salts and phospholipases.

Incubation of bovine CNS myelin with phospholipase C from Bacillus cereus under conditions that lead to extensive phospholipid degradation caused 10% of the myelin protein to be released from the membrane. The myelin basic protein (MBP) was a major component of the dissolved protein. Comparable incubations with phospholipase C from Clostridium perfringens, phosphatidylinositol-specific phospholipase C from Staphylococcus aureus, or cabbage phospholipase D removed little MBP. However, concentrations of sodium chloride near 1 M and concentrations of divalent metal ions between 50 and 600 mM released typically 9-12% of the total myelin protein, with MBP again as the predominant component. Repetitive washing with calcium chloride solutions resulted in dissolution of over 90% of the MBP. When myelin was incubated in 1.0 M sodium chloride or 25 mM calcium chloride, the MBP was cleaved largely into two major peptides with apparent molecular weights near 14,000 and 12,000, but with 200 mM or higher concentrations of calcium chloride most of this protein remained intact. With appropriate manipulation of the ionic milieu, it is thus possible to remove most of this extrinsic protein from the myelin surface under relatively mild conditions. The conditions that release the protein suggest that it is held at the membrane surface by ionic interactions.

Animals↗

Iontophoretic delivery of calcium for experimental hydrofluoric acid burns.

OBJECTIVE: To examine the efficacy of iontophoretic delivery of calcium to experimental hydrofluoric acid burns. DESIGN: Prospective, controlled study. SETTING: Institutional laboratory. SUBJECTS: Male nude rats. INTERVENTIONS: For the in vitro experiment, a full-thickness skin from the back was set in a vertical flow-through diffusion cell. Calcium chloride was applied to the donor chamber, and transdermal transport of calcium was examined with or without a voltage gradient of 1.5 V. Either intact skin or skin whose stratum corneum was stripped with adhesive tapes was used. For the in vivo experiment, hydrofluoric acid burns were induced by dispensing 50% hydrofluoric acid (50 microL) on the backs of the nude rats, who were under pentobarbital anesthesia. Rats were divided into four groups (n = 5 for each group): control group (burned but not treated); topical group (treated with calcium gluconate jelly); infiltration group (intradermal and subcutaneous injection of calcium gluconate); and iontophoresis group (treated with iontophoresis of calcium chloride at 1.5 V). Burn areas were measured and pathologic findings were classified microscopically into five stages at 1 wk: stage 1, epidermal burn; stage 2, superficial dermal burn; stage 3, deep dermal burn; stage 4, full-thickness burn; and stage 5, burn affecting the skeletal muscle. MEASUREMENTS AND MAIN RESULTS: In the in vitro experiment, calcium concentrations increased significantly only in stripped skins with a 1.5-V gradient. In the in vitro experiment, burn areas were reduced significantly in the iontophoresis group compared with the other three groups. Pathologic findings were significantly improved in the iontophoresis group compared with the control group. This efficacy of iontophoresis was observed when it was initiated within 30 mins after hydrofluoric acid burn. CONCLUSIONS: These results show that transdermal transport of calcium was enhanced in stripped skins by iontophoresis and that iontophoresis was more efficacious than topical or infiltration therapy for experimental hydrofluoric acid burns. Iontophoretic delivery of calcium seems to be easier than intra-arterial infusion and may be effective for the lesions where intra-arterial infusion is difficult.

Administration, Topical↗

The effects of pH, calcium and chloride ions on the binding of tolmetin to human serum albumin: circular dichroic, dialysis and fluorometric measurements.

The binding of the non-steroidal anti-inflammatory drug, tolmetin (1-methyl-5-p-toluoylpyrrole-2-acetic acid) to human serum albumin (HSA) has been shown by circular dichroism, fluorescence and equilibrium dialysis to be dependent on the N-B conformational change of the albumin. The influence of calcium and chloride ions on the interaction was also investigated using the same techniques. Experiments suggested that calcium ions increased the binding constant of tolmetin to HSA whereas chloride ions decreased it. The displacement study showed that tolmetin caused a significant increase in the affinity of diazepam to HSA whereas it decreased the binding of warfarin to HSA. Tolmetin seems to cause an allosteric change in the diazepam binding site in spite of it sharing a primary site with warfarin.

Calcium↗

Differential expression of calcium-activated chloride channels (CLCA) gene family members in the small intestine of cystic fibrosis mouse models.

Members of the family of calcium-activated chloride channels (CLCA) have been implicated as modulators of the phenotype in cystic fibrosis (CF). Here, the expression levels of the murine mCLCA1, mCLCA2, mCLCA3 and mCLCA4 were quantified by real-time RT-PCR in the small intestines of CF (cftr (tm1Cam), cftr (TgH(neoim)1Hgu)) and wild type C57BL/6, BALB/c, DBA/2 and NMRI mice. Markedly different expression levels of all four CLCA homologs were observed between the different wild type strains. Expression of mCLCA1 and mCLCA4 was similar in CF versus wild type. In contrast, mCLCA3 mRNA copy numbers were increased up to threefold in all CF models. Immunohistochemical detection of mCLCA3 and PAS reactions on consecutive tissue sections identified a similar increase in mCLCA3 expressing goblet cells, suggesting that elevated mRNA copy numbers of mCLCA3 are due to goblet cell hyperplasia rather than transcriptional regulatory events. Increased mCLCA2 mRNA copy numbers, however, were considered more likely to be due to transcriptional upregulation. Changes in mRNA copy numbers were not associated with altered cell kinetics as determined by immunohistochemistry using antibodies to phospho-histone 3 and activated caspase-3. The results suggest that both mCLCA2 and mCLCA3 may act as modifiers of the intestinal phenotype in CF.

Animals↗

Effect of dopamine receptor anatagonists on the calcium-dependent central function that reduces blood pressure in spontaneously hypertensive rats.

The effects of intracerebroventricular (i.c.v.) administration of dopamine receptor antagonists on the calcium-dependent brain function that reduces blood pressure were investigated. The systolic blood pressure of spontaneously hypertensive rats (SHR; male, 13 weeks of age) was reduced following i.c.v. administration of calcium chloride (100 microg/rat), and this effect of calcium chloride was attenuated by i.c.v. injection of eticlopride (dopamine D2 receptor antagonist, 100 microg/rat), but not by i.c.v. injection of SCH 23390 (dopamine D1 receptor antagonist, 30 microg/rat). Taking into consideration these results with our previous reports, it is suggested that calcium enhances dopamine synthesis in the brain through a calmodulin-dependent system, and that the resultant increase in dopamine levels inhibits sympathetic activity via the dopamine D2 receptor in the brain and reduces the blood pressure in SHR.

Animals↗

[Cloning and expression of the extracellular domain of calcium-activated chloride channel in mouse airway goblet cells].

AIM: To clone and express the extracellular domain of murine calcium-activated chloride channel (mCLCA3) in airway goblet cell of mouse. METHODS: According to the gene sequence of mCLCA3 the PCR primers for N-terminal, middle and C-terminal extracellular domains were designed. Using recombinant plasmid pcDNA3.1(-)/mCLCA3 as template, the DNAs coding for the three extracellular domains were amplified. And then the DNAs encoding N-terminal and C-terminal extracellular domains were inserted into expression vector pRSET-A, while the middle extracellular domain DNA was inserted into pGEX-T1. E.coli. BL21(DE3) were transformed with the three recombinant plasmids, respectively, and were induced with IPTG for expression. RESULTS: DNA sequencing showed that the cloned DNAs encoding extracellular domains were identical with those in GenBank (GenBank accession No. NM-017474 ). The 3 domains were expressed in E.coli and most of the expressed products existed in the form of inclusion body. CONCLUSION: The expression of three extracellular domains of mCLCA3 lays the foundation for further preparing anti-mCLCA3 antibody and exploring the mechanism of modulation of mCLCA3.

Animals↗

Hypersensitivity to calcium associated with an increased sarcolemmal Ca2+-ATPase activity in diabetic rat heart.

Sarcolemmal Ca2+-dependent ATPase activity and the mechanical response to calcium and verapamil were studied in myocardium from normal rats and those with diabetes induced by streptozotocin. Sarcolemmal Ca2+-ATPase activity was increased in diabetic animals, depending on the duration of the diabetes. Both the maximal velocity and the affinity were greater in hearts of diabetic rats compared with normal controls. In insulin treated diabetic hearts the affinity of the enzyme for calcium decreased but the maximal velocity was not modified. The enzyme activity was stimulated maximally by millimolar concentrations of calcium and inhibited by lanthanum chloride. Calcium induced a concentration dependent increase in dF/dt in normal and diabetic hearts, but in diabetes the dose-response curve to calcium chloride was shifted to the left. Verapamil depressed the dF/dt in a concentration dependent manner in normal and diabetic hearts; but the drug was more effective in diabetic than in normal rats. These results suggest that an increase in sarcolemmal Ca2+-ATPase activity may be of critical importance in the hypersensitivity of diabetic heart in the presence of low extracellular calcium and calcium blockade.

Animals↗

Effect of postmortem injection time and postinjection aging time on the calcium-activated tenderization process in beef.

The objectives of this study were to determine 1) the effectiveness of calcium chloride when injected later than 2 d postmortem, 2) the effect of extended postinjection aging time, and 3) the tenderness response curve in calcium chloride-treated beef. In Exp. 1, the longissimus thoracis et lumborum was injected on either d 2 or 14 postmortem with 5% by weight of a 200 mM calcium chloride solution. Samples were aged (1 degree C) either 7 or 35 d after injection. The uninjected control longissimus from the contralateral side was aged for 9, 21, 37, or 49 d. In Exp. 2, the longissimus thoracis et lumborum was injected on d 2 postmortem with 5% by weight of a 200 m x M calcium chloride solution then sampled for shear force on d 1, 2, 6, 8, 12, and 14 after injection. Calcium chloride injection, regardless of injection time or postinjection aging time, had higher (P < .05) sensory tenderness rating than control with the same total aging time (5.2, 5.5, 5.8, and 6.1 vs 4.3, 4.8, 5.1, and 5.3, respectively). Calcium chloride injection at d 14 reduced shear force (.7 kg) and increased tenderness rating (.7 units) as effectively (P > .05) as injection at d 2 (1.2 kg and .8 units, respectively). Calcium chloride-injected steaks had higher (P < .05) juiciness ratings than control steaks. Postrigor calcium chloride injection reduced (P < .05) shear force within 1 d after injection and resulted in more tender meat through 14 d after injection. Extended postinjection aging (35 d) had little effect on color display stability. Calcium activated tenderization can be applied as late as 14 d postmortem and will reduce the occurrence of tough meat if aging is limited.

Animals↗

The effect of tetraethylammonium chloride on calcium fluxes in smooth muscle from rabbit main pulmonary artery.

1. In the first part of this investigation we studied the experimental conditions under which the 'lanthanum method' gives valid estimations of the changes in intracellular calcium induced by either tetraethylammonium chloride (TEA) or high K in the rabbit main pulmonary artery. Subsequently, the effect of TEA on Ca movements in this blood vessel was measured. 2. The uptake of 140La by the vascular tissue is time- and concentration-dependent; it is separated into an early and a late phase. La binds to at least two classes of extracellular sites with affinities of 0.06 and 4.76 M. 3. A 1 hr exposure of the vascular strips to a 1 mM-La solution appears to be a convenient treatment for removal of Ca from the extracellular space. Under these conditions (a) 45Ca efflux from an intracellular compartment loaded with Ca during exposure to TEA or K is virtually blocked, (b) there is no major penetration of La into the smooth muscle cells as revealed by electron microscopy, and (c) there is no change in the size of the extracellular space. 4. TEA increases in a concentration-dependent manner the La-resistant 45Ca content (maximum increase 0.18 m-mole 45Ca/kg wet weight in response to 70 mM-TEA). There is a linear relationship between log concentration TEA and 45Ca influx. 5. The calcium antagonist verapamil (10(-6) and 10(-5) M) inhibits the TEA-induced 45Ca influx. 6. The increase in 45Ca influx produced by K (20 or 30 mM) is markedly enhanced by TEA. 7. The noradrenaline-induced increase in 45Ca accumulation is not influenced by TEA. 8. 45Ca efflux from the La-resistant Ca space is increased by TEA both in the presence and in the absence of non-radioactive Ca in the medium. 9. It is concluded that TEA contracts the vascular smooth muscle cells of the rabbit main pulmonary artery by an increase in the Ca permeability of the cell membrane.

Animals↗

Gene expression and immunolocalisation of a calcium-activated chloride channel during the stratification of cultivated and developing corneal epithelium.

The spatial and temporal localisation of a calcium-activated chloride channel (CLCA) and its mRNA was investigated, during the in vivo and in vitro development of stratified epithelia, by fluorescence immunohistochemistry and quantitative polymerase chain reaction in embryonic chicken corneas and the expansion of excised human corneal stem cells on amniotic membrane. Single-layered human epithelial cultures on amniotic membrane and early day embryonic chicken corneas expressed relatively little human CLCA2 or its chicken homologue. However, as the epithelium in both models matured and the number of cell-layers increased, the gene expression level and protein staining intensity increased, primarily within the basal cells of both the cultured and embryonic tissues. These results demonstrate that human CLCA2 protein and mRNA expression are elevated during epithelial stratification, suggesting that this protein plays a role in the growth of multi-layered corneal epithelia during both natural development and tissue cultivation.

Animals↗

Tissue analysis by dual-energy computed tomography.

A straightforward method of tissue analysis from dual-energy computed tomography (CT) is presented which does not rely on previous inaccurate or incorrect formulations of the X-ray attenuation coefficient. The attenuation coefficients of tissue and bone were represented by a mixture of two reference materials. For convenience, water and calcium chloride were chosen. After careful calibration of the CT scanner, a dual-energy CT scan yields the water and calcium chloride in units of kg/kg multiplied by the specific gravity of the tissue. For an error of +/- 2 HU on dual-energy scans at 140 kVp and 87 kVp on an EMI CT5005 general-purpose scanner, the error on the calcium chloride coefficients is +/- 0.004 kg/kg. Fat concentrations greater than 25% by weight may be detected when the coefficients are averaged over at least 200 pixels. Bone mineral content could be measured with a precision of 0.01 (in units of kg/kg multiplied by specific gravity) for averaging regions of 24 pixels. Iodine concentrations in tissue can be deduced if water and iodine are chosen as the reference materials. Clinical examples are presented to illustrate the technique for scans of both the head and the abdomen.

Abdominal Neoplasms↗

Dissolution of various calcium fluoride preparations in inorganic solutions and in stimulated human saliva.

The aim of the present study was to examine the dissolution of various preparations of calcium fluoride in inorganic solutions and in human saliva. Calcium fluoride was prepared by mixing either 0.25 or 0.02 mol/l calcium chloride with 0.5 or 0.04 mol/l sodium fluoride. After preparation, the salts were washed in 1 mmol/l calcium chloride solution and in distilled water. A commercial product, calcium fluoride Suprapur (Merck), was used for comparison. The solubility of the salts was examined in distilled water, in a 2-mmol/l sodium phosphate solution, and in whole human saliva, produced by chewing paraffin. It was found that the calcium fluoride ion product after suspension for 1-3 h in distilled water ranged closely around 10(-10.7) for all salts. In the phosphate solution, the commercial product dissolved slowly, the ratio between dissolved fluoride and calcium ranged from 4 to 7, in buffered solutions approaching 2. The supernatant was not saturated by the salt. Our two calcium fluoride salts dissolved quickly and made the phosphate-containing solutions supersaturated with respect to fluorapatite, leading to fluorapatite formation, and because of compensating calcium fluoride dissolution, this led to increasing fluoride concentrations in saliva of up to around 85-95 ppm. The results of this study indicate that calcium fluoride of less than Suprapur standard may dissolve quickly in saliva, unless the dissolution is retarded by a physical barrier, like a forming pellicle.

Apatites↗