Calcium level

Mild exposure to HF via inhalation can irritate the nose, throat, and respiratory system. The onset of symptoms may be delayed for several hours. Severe exposure via inhalation can cause nose and throat bums, lung inflammation, and pulmonary edema, and can also result in other systemic effects including hypocalcemia (depletion of body calcium levels), which if not promptly treated can be fatal. Permissible air concentrations are (42) OSHA PEL, 3 ppm (2.0 mg/m ) as E OSHA STEL, 6 ppm (5.2 mg/m ) as E and ACGIH TLV, 3 ppm (2.6 mg/m ) as E. Ingestion can cause severe mouth, throat, and stomach bums, and maybe fatal. Hypocalcemia is possible even if exposure consists of small amounts or dilute solutions of HE. 

Calcitonin is secreted when abnormally high calcium levels occur in plasma. Although plasma concentrations are normally minute (<100 pg/mL), they increase two- to threefold after calcium infusion. Calcitonin has a short plasma half-life (ca 10 min). Certain thyroid tumors are the result of CT concentrations 50—500 times normal. The mechanism of action is a direct inhibition of bone resorption. Calcitonin is used clinically in various diseases in which hypercalcemia is present, eg, Paget s disease (46). 

Hydroxy vitamin D pools ia the blood and is transported on DBF to the kidney, where further hydroxylation takes place at C-1 or C-24 ia response to calcium levels. l-Hydroxylation occurs primarily ia the kidney mitochondria and is cataly2ed by a mixed-function monooxygenase with a specific cytochrome P-450 (52,179,180). 1 a- and 24-Hydroxylation of 25-hydroxycholecalciferol has also been shown to take place ia the placenta of pregnant mammals and ia bone cells, as well as ia the epidermis. Low phosphate levels also stimulate 1,25-dihydtoxycholecalciferol production, which ia turn stimulates intestinal calcium as well as phosphoms absorption. It also mobilizes these minerals from bone and decreases their kidney excretion. Together with PTH, calcitriol also stimulates renal reabsorption of the calcium and phosphoms by the proximal tubules (51,141,181—183). 

Although it is being found that vitamin D metaboUtes play a role ia many different biological functions, metaboHsm primarily occurs to maintain the calcium homeostasis of the body. When calcium semm levels fall below the normal range, 1 a,25-dihydroxy-vitainin is made when calcium levels are at or above this level, 24,25-dihydroxycholecalciferol is made, and 1 a-hydroxylase activity is discontiaued. The calcium homeostasis mechanism iavolves a hypocalcemic stimulus, which iaduces the secretion of parathyroid hormone. This causes phosphate diuresis ia the kidney, which stimulates the 1 a-hydroxylase activity and causes the hydroxylation of 25-hydroxy-vitamin D to 1 a,25-dihydroxycholecalciferol. Parathyroid hormone and 1,25-dihydroxycholecalciferol act at the bone site cooperatively to stimulate calcium mobilization from the bone (see Hormones). Calcium blood levels are also iafluenced by the effects of the metaboUte on intestinal absorption and renal resorption. 

Sodium C rbon te. Sodium carbonate softens water by forming insoluble calcium carbonate with calcium ions in hard water. Carbonate can also reduce calcium levels by ion pairing, although the benefit to detergency is questionable. Buildup of calcium carbonate on machine and fabrics, which can occur with time, is undesirable. Sodium carbonate [497-19-8] does not provide any suspending action. It does, however, provide alkalinity to the wash hquor and is an effective alkah. 

White phosphorus. This element burns in air and can produce severe thermal and chemical burns. It may reignite on drying. After washing, rapid but brief treatment with copper sulphate (to avoid systemic absorption and copper poisoning) is used to convert the phosphorus to copper phosphide which is then removed Hydrogen fluoride. This can form painful but delayed necrosis. Treat with calcium gluconate locally and monitoring of serum calcium levels, with administration of calcium where necessary... 

The behavior of calcium in the cells can be considered as a metabolic process. There is uptake, distribution, and excretion of calcium in the cells. The uptake of calcium occurs via activation of calcium channels. The end result is elevation of intracellular calcium levels and subsequent activation. Be-... 

A small excess of soda ash, of 0.57 kg/m (0.2 Ib/bbl), should be maintained to ensure the calcium level remains below 80 mg/1 and to improve the efficiency of the extender. This level of soda ash will produce the required pH in most cases. 

Gilroy, S., Hughes, W. A., and Trewavas, A. J. (1989). A comparison between Quin-2 and aequorin as indicators of cytoplasmic calcium levels in higher plant cell protoplasts. Plant Physiol. 90 482—491. 

The steroid hormone 1,25-dihydroxy vitamin D3 (calcitriol) slowly increases both intestinal calcium absorption and bone resorption, and is also stimulated through low calcium levels. In contrast, calcitonin rapidly inhibits osteoclast activity and thus decreases serum calcium levels. Calcitonin is secreted by the clear cells of the thyroid and inhibits osteoclast activity by increasing the intracellular cyclic AMP content via binding to a specific cell surface receptor, thus causing a contraction of the resorbing cell membrane. The biological relevance of calcitonin in human calcium homeostasis is not well established. 

PTH has a dual effect on bone cells, depending on the temporal mode of administration given intermittently, PTH stimulates osteoblast activity and leads to substantial increases in bone density. In contrast, when given (or secreted) continuously, PTH stimulates osteoclast-mediated bone resorption and suppresses osteoblast activity. Further to its direct effects on bone cells, PTH also enhances renal calcium re-absorption and phosphate clearance, as well as renal synthesis of 1,25-dihydroxy vitamin D. Both PTH and 1,25-dihydroxyvitamin D act synergistically on bone to increase serum calcium levels and are closely involved in the regulation of the calcium/phosphate balance. The anabolic effects of PTH on osteoblasts are probably both direct and indirect via growth factors such as IGF-1 and TGF 3. The multiple signal transduction... 

Calcium-dependent regulation involves the calcium-calmodulin complex that activates smooth muscle MLCK, a monomer of approximately 135 kDa. Dephosphorylation is initiated by MLCP. MLCP is a complex of three proteins a 110-130 kDa myosin phosphatase targeting and regulatory subunit (MYPT1), a 37 kDa catalytic subunit (PP-1C) and a 20 kDa subunit of unknown function. In most cases, calcium-independent regulation of smooth muscle tone is achieved by inhibition of MLCP activity at constant calcium level inducing an increase in phospho-rMLC and contraction (Fig. 1). 

Determining calcium levels normally does not identify hardness breakthrough because the calcium salt simply reacts with phosphate precipitant (or similar treatment) and is lost as a sludge. It does, however, produce an immediate and noticeable reduction in alkalinity. (Calcium bicarbonate breaks down to calcium carbonate and carbonic acid.)... 

When alendronate and risedronate are administered, serum calcium levels are monitored before, during, and after therapy. 

When these drugs are given to the female patient with inoperable breast carcinoma, tire nurse evaluates the patient s current status (physical, emotional, and nutritional) carefully and records tire finding in tire patient s chart. Problem areas, such as pain, any limitation of motion, and the ability to participate in tire activities of daily living, are carefully evaluated and recorded in tiie patient s record. The nurse takes and records vital signs and weight. Baseline laboratory tests may include a complete blood count, hepatic function tests, serum electrolytes, and serum and urinary calcium levels. The nurse reviews these tests and notes any abnormalities. 

Figure 2. Muscle stimulation, a) a single nerve impulse (stimulus) causes a single contraction (a twitch). There is a small delay following the stimulus before force rises called the latent period, b) A train of stimuli at a low frequency causes an unfused tetanus. Force increases after each progressive stimulus towards a maximum, as calcium levels in the myofibrillar space increase. But there is enough time between each stimulus for calcium to be partially taken back up into the sarcoplasmic reticulum allowing partial relaxation before the next stimulus occurs, c) A train of stimuli at a higher frequency causes a fused tetanus, and force is maximum. There is not enough time for force to relax between stimuli. In the contractions shown here, the ends of the muscle are held fixed the contractions are isometric.

Calcium levels in the myofibrillar space are usually low, to prevent contraction. The calcium ions are stored in an internal membrane system called the sarcoplasmic... 

Previous studies indicate that osmotic gradients promote membrane fusion, while hyperosmotic conditions inhibit membrane fusion during exocytosis. Consistent with this idea is the observation that the release of lysosomal enzymes from rabbit neutrophils, induced by the chemotactic peptide J -formylmethionyl-leucyl-phenylalanine (FMLP), is inhibited almost 80% in a 700-mosmol/kg medium. Inhibition is immediate (within 10 s), increases with osmolality, and is independent of the osmoticant. Neutrophils loaded with the calcium indicator indo-1 exhibit an FMLP-induced calcium signal that is inhibited by hyperosmolality. Hyperosmolality (700 mosmol/kg) increases basal calcium levels and reduces the peak of the calcium signal elicited by FMLP at concentrations ranging from 10 ° to 10 M. 

Figure 2. Reporting of cytosolic free calcium levels by indo-1. Increases in cytosolic calcium, due either to entry of extracellular calcium via calcium channels or to release of intracellular calcium sequestered in organelles such as smooth endoplasmic reticulum, results in formation of the indo-l-calcium complex. Fluorescence intensity at 400 nm (excitation at 340 nm) is proportional to the concentration of this complex the dissociation constant for this complex is about 250 nff (24), making this probe useful for detecting calcium activities in the range of 25 to 2500 nJ. ...

Wasserman, R., Comar, C.L. and Papadopoulou, D. 1957 Dietary calcium levels and retention of radiostrontium in the growing rat. Science 126 1180-1182. 

Ozmen G, Elcuman A. 1998. [Combined effects of endosulfan dimethoate and carbaryl on serum calcium levels and heart muscle of rats] Turk J Biol 22 317-322. (Turkish)... 

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