Effects of solution calcium concentration and calcium sink size on the dissolution of Gafsa phosphate rock in soils

SummaryWe have investigated the effects of 1-desamino-8-D-arginine vasopressin (DDAVP) infusion on platelet count and bleeding time in 4 patients with type IIB von Willebrand’s disease (vWd). Three of four patients showed a normalization of the bleeding time within 1 h after the infusion, while bleeding time was not modified in the fourth. In accordance with the literature, thrombocytopenia was observed after DDAVP infusion, but this thrombocytopenia was due to the anticoagulants used for blood collection. In two patients (F. I., G. F.) no thrombocytopenia was observed when platelets were counted by fingerstick method but there was a 20% platelet decrease in blood samples collected in sodium citrate and a 50% decrease in samples collected in EDTA. Dramatic falls in platelet counts (70–95%) were observed in the additional two patients (C. A., D.Z.) after DDAVP infusion, when both sodium citrate or EDTA were used as anticoagulants. In the latter two patients there was also a 50% decrease in platelet count when the fingerstick method was used. The decrease in the patient’s platelet count in EDTA samples after DDAVP infusion could be prevented, in part, by the previous additions of an anti GPIb monoclonal antibody and an anti GPIIb-IIIa monoclonal antibody.Thus, the thrombocytopenia observed in the four IIB vWd patients studied after DDAVP infusion seems to be, at least partially, a pseudothrombocytopenia depending on the calcium concentration in the blood samples and the availability of GPIb and GPIIb-IIIa receptors. These findings and the normalization of the bleeding time observed in three of the four patients has led us to reconsider the possible use of DDAVP in the treatment of our IIB vWd patients.

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Hypersensitivity to Thromboxane A2 in Cholesterol-Rich Human Platelets

Thrombosis and Haemostasis ◽

10.1055/s-0038-1647364 ◽

1990 ◽

Vol 64 (04) ◽

pp. 594-599 ◽

Cited By ~ 16

Author(s):

Takuya Tomizuka ◽

Kyohei Yamamoto ◽

Aizan Hirai ◽

Yasushi Tamura ◽

Sho Yoshida

Keyword(s):

Calcium Concentration ◽

Binding Capacity ◽

Thromboxane A2 ◽

Cytosolic Calcium ◽

Cholesterol Content ◽

Human Platelets ◽

Dissociation Rate ◽

Platelet Membrane ◽

Maximal Concentration ◽

Equilibrium Dissociation

SummaryThe effect of changes in platelet membrane cholesterol content on thromboxane A2 (TXA2)-induced platelet activation was studied. Concentrations of 9,ll-epithio-ll,12-methano-TXA2 (STA2), a stable analogue of TXA2 which can cause half-maximal aggregation and release of [14C]serotonin in cholesterol-rich platelets were significantly lower than those in cholesterol-normal platelets. STA2-induced increase in cytosolic calcium concentration and [32P]phosphatidic acid formation in cholesterol-rich platelets were significantly greater than those in cholesterol-normal platelets. The maximal concentration of binding site (Bmax) for SQ29548 was significantly increased in cholesterol-rich platelets compared with cholesterol-normal platelets, while the equilibrium dissociation rate constant (Kd) for SQ29548 did not differ between cholesterol-rich and cholesterol-normal platelets. The present study suggested that sensitivity to TXA2 was increased by the incorporation of cholesterol into platelet membrane and that the cause of hypersensitivity to TXA2 in cholesterol-rich platelets may be partly explained by an increase in binding capacity for TXA2.

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The Effect of Calcium and Magnesium on Rabbit Blood Platelet Aggregation in Vitro

Thrombosis and Haemostasis ◽

10.1055/s-0038-1655584 ◽

1964 ◽

Vol 12 (01) ◽

pp. 179-200 ◽

Cited By ~ 17

Author(s):

Torstein Hovig

Keyword(s):

Platelet Aggregation ◽

Cation Exchange ◽

Calcium Concentration ◽

Blood Platelets ◽

Blood Platelet ◽

Rabbit Blood ◽

Calcium And Magnesium ◽

Induced Aggregation ◽

Blood Platelet Aggregation

SummaryThe effect of calcium and magnesium on the aggregation of rabbit blood platelets in vitro was studied, with the following results:1. Platelet aggregation induced by ADP or collagen could be prevented by EGTA or EDTA. The aggregating effect was restored by recalcification. The effect was also restored by addition of magnesium in EDTA-PRP, but not in EGTA-PRP unless a surplus of calcium was present.2. Calcium remained in concentrations of the order of 0.15–0.25 mM after dialysis or cation exchange of plasma. Aggregation of washed platelets resuspended in such plasma could not be produced with ADP or collagen, unless the calcium concentration was increased or that magnesium was added.3. The adhesiveness of blood platelets to collagen was reduced in EGTA-PRP and EDTA-PRP. Release of ADP from platelets influenced by collagen could not be demonstrated either in EGTA-PRP (presence of magnesium) or in EDTA-PRP.4. It is concluded that calcium is a necessary factor both for the reaction leading to release of ADP and for the the aggregation produced by ADP.5. Thrombin induced aggregation of washed platelets suspended in tris-buffered saline in the presence of calcium. No effect of magnesium could be observed unless small quantities of calcium were present.

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ALTERNATIVE P-FERTILISERS FOR NORTHLAND SOILS

Proceedings of the New Zealand Grassland Association ◽

10.33584/jnzg.1986.47.1734 ◽

1986 ◽

pp. 229-232

Author(s):

P.W. Shannon

Keyword(s):

Phosphate Rock ◽

Growth Responses ◽

Triple Superphosphate ◽

Rock Phosphates ◽

Distribution Costs ◽

Phosphate Retention ◽

Sechura Phosphate Rock ◽

Local Product ◽

Application Frequency ◽

Chatham Rise Phosphorite

Increasing material, processing, and distribution costs have raised superphosphate prices to a point where many farms cannot support the costs of meeting maintenance phosphate requires men& Alternatives to superphosphate, particularly those that have lower processing costs and contain more P, may offer a solution to the problem provided they are agronomically as effective. Phosphate rock may indeed be such an alternative. Preliminary results from a series of five trials in Northland show that on soils of moderate P fertility, with low phosphate retention (PR) and high pH (5.9.6.0), initial pasture growth responses to rock phosphates are smaller than those from single or triple superphosphate. On one soil of higher PR and lower pH, the differences in yield between the rock-phosphates and the super. phosphates were smaller. Of the rock phosphates tested, Sechura and North Carolina (unground and ungranulated) tended to be more effective than ground and granulated Chatham Rise phosphorite. The effect on production of applying fertilisers once every three years, as opposed to annual applications is being investigated using triple superphosphate and Sechura phosphate rock. After two years, production levels appear largely unaffected by differences in application frequency. A comparison of locally-produced superphosphate with a reference standard showed that both performed similarly, indicating that the local product was of satisfactory quality.

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ABOLITION OF MAGNESIUM-INDUCED HYPOCALCAEMIA BY ACUTE THYRO-PARATHYROIDECTOMY IN THE CAT

Acta Endocrinologica ◽

10.1530/acta.0.0640150 ◽

1970 ◽

Vol 64 (1) ◽

pp. 150-158 ◽

Cited By ~ 3

Author(s):

S. Pors Nielsen

Keyword(s):

Sodium Chloride ◽

Flow Rate ◽

Magnesium Chloride ◽

Calcium Concentration ◽

Plasma Calcium ◽

Magnesium Concentration ◽

Isotonic Sodium Chloride ◽

Plasma Calcium Concentration ◽

High Concentrations ◽

Plasma Magnesium

ABSTRACT Intravenous infusion of isotonic magnesium chloride into young cats with a resultant mean plasma magnesium concentration of 7.7 meq./100 g protein was followed by a significant lowering of the plasma calcium concentration in 90 minutes. The rate of decrease of plasma calcium is consistent with the hypothesis that calcitonin is released by magnesium in high concentrations. There was no decrease in the plasma calcium concentration in cats of the same weight thyroparathyroidectomized 60 min before an identical magnesium chloride infusion or an infusion of isotonic sodium chloride at the same flow rate. The hypercalciuric effect of magnesium could not account for the hypocalcaemic effect of magnesium. Plasma magnesium concentration during magnesium infusion into cats with an intact thyroid-parathyroid gland complex was slightly, but not significantly higher than in acutely thyroparathyroidectomized cats.

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Localization of calcium and zinc in the sperm storage tubules of chicken, quail and turkey using X-ray microanalysis

Reproduction ◽

10.1530/reprod/118.2.331 ◽

2000 ◽

pp. 331-336 ◽

Cited By ~ 9

Author(s):

L Holm ◽

H Ekwall ◽

GJ Wishart ◽

Y Ridderstrale

Keyword(s):

Calcium Concentration ◽

Sperm Storage ◽

X Ray ◽

Elemental Concentrations ◽

Low Concentrations ◽

Intracellular Content ◽

Wet Weight ◽

The Mean ◽

Sperm Storage Tubules ◽

Scanning Electron

Sperm storage tubules from the utero-vaginal junction of chickens, quails and turkeys were analysed for calcium and zinc using X-ray microanalysis of ultra-rapidly frozen tissue in a scanning electron microscope. This technique enabled the tubular fluid surrounding the stored spermatozoa and the intracellular content of the cells of the sperm storage tubules to be analysed separately and, by using standards with known concentrations, their elemental concentrations were estimated. The mean (+/- SEM) concentration of calcium in the tubular fluid from chickens, quails and turkeys was 17 +/- 3, 19 +/- 3 and 17 +/- 4 mmol kg(-1) wet weight, respectively. The intracellular calcium concentration of the cells of the tubules did not differ significantly from these values and was also similar in the mucosal epithelial cells of the utero-vaginal junction. Zinc was localized in the cells of turkey sperm storage tubules and tubular fluid, but at low concentrations. No zinc could be detected in corresponding structures from chickens and quails. The concentration of calcium in the tubular fluid is within the range known to inhibit the motility of spermatozoa, supporting this function for calcium during storage. Zinc is known to depress turkey sperm metabolism and it may also be involved in inducing quiescence of spermatozoa during storage in this species.

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