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The study was designed to determine the calciuretic effect of furosemide and its impact upon calcium balance during chronic (25 days) furosemide administration to growing rats. Experiments were performed on 18 six-wk-old rats. Nine animals received furosemide, and 9 served as controls. The administration of furosemide in a dose of 40 mg resulted in a significant increase in calcium excretion in the treated group; urinary calcium excretion almost doubled that of the controls during the first 24-hr collection (3.74 +/- 0.44 mg in the treated animals compared with 1.90 +/- 0.15 mg in the controls; P less than 0.05). The average daily urinary calcium excretion during each of four subsequent 6-day periods remained approximately three-fold higher in animals which received furosemide compared with controls (P less than 0.001 for each 6-day period). The furosemide-induced increase in urinary calcium excretion did not diminish with time. Sodium excretion did not significantly increase either acutely or chronically in response to furosemide. Daily urinary volume increased approximately 40 to 60% in the furosemide-treated group compared with that of the controls (P less than 0.001). The cumulative calcium balance in the control group exceeded by 7% that of the furosemide-treated animals [2696.3 +/- 20.8 mg versus 2518.6 +/- 20.1 mg (P less than .001]. The findings indicate that distal nephron compensatory mechanisms effecting sodium conservation following furosemide do not result in similar conservation of calcium. Calcium balance may be deleteriously affected.

Net absorption of calcium, calcium balance and bone mineral content were studied in 83 patients with small-bowel resections of various lengths, mainly owing to CIBD, while they were receiving a standardized diet supplying 70 g fat and 800 mg calcium. Median duration of disease was 9 years (range, 5 months to 53 years) and median length of time from resection 3 years (range, 2 months to 18 years). In the whole case material net absorption of calcium ranged from +573 to −268 mg/day; median, +65 mg/day (+56% to −26% of dietary calcium; median, +6%). A weak inverse correlation was found between net absorption of calcium and length of resected small bowel, both in patients with ileostomy (no. = 32, r = −0.43, p < 0.01) and in patients with part of or the whole colon in function (no. = 51, r=−0.34, p < 0.01). Net absorption of calcium and urinary calcium correlated only weakly (no. = 78, r = 0.39, p < 0.001). In all patients studied the median calcium balance was −49 mg/day (range. +447 to −339 mg/day). No diff...

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Prostaglandins (PGs) are known to have various effects on bone metabolism. The supplementation of essential fatty acids (EFAs), the precursors of PGs, leads to increased intestinal calcium absorption and calcium balance. It is, however, not known whether increased calcium absorption and calcium balance will enhance the calcium content in bone. Male Sprague-Dawley rats (n = 40) aged 5-12 weeks were supplemented with EFAs. The main dietary EFAs, linoleic acid (LA) and alpha-linolenic acid (ALA) were administered in a ratio of 3:1 as a control group. The conversion of LA to ALA to the PG precursors is slow, with the first step, delta-6-desaturation being rate limiting. Fatty acids beyond this rate-limiting step, gamma-linolenic acid (GLA, n-6) and eicoapentaenioc acid (EPA, n-3), were administered to different groups in the ratios 3:1, 1:1 and 1:3 to explore the impact of different ratios of n-6 and n-3 EFAs. Intestinal calcium absorption (mg/24 h) increased by 41.5% in the 3:1 supplemented group, compared with the control group. The decrease in urinary calcium (mg/24 h) correlated with the increase in n-3 level. The calcium balance (mg/24 h) and bone calcium (mg/g bone ash) increased significantly in the 3:1 (41.5% and 24.7%) group, compared with the control. The increase in bone calcium might be attributed to an EFA-induced increase in circulating PGs. An increased synthesis of PGs acting on target bone cells, as well as changes in membrane fluidity, may underlie these observations.

One serious difficulty with calcium balance studies is the unpredictable fecal excretion of calcium which follows ir-regular bowel habits. The calcium balance is often impossible to evaluate because of the error introduced by inadequate demarcation of feces. The significance of the demarcation error can be evaluated in the course of a balance study by a simple, continuous registration of the cumulative calcium balance expressed in mg./day. A calcium balance study should not be discontinued before the cumulative balance has attained a plateau for at least 3–4 periods. The length of the study will thus be dependent on the bowel habits of the subject studied. At a large calcium intake the plateau is generally obtained later than at a low one.

The effects of menatetrenone (2-methyl-3-tetraprenyl-1,4-naphthoquinone, MK-4) on calcium balance were studied in male Sprague-Dawley rats. Experiment 1: Rats in metabolic cages that were fed a vitamin K-deficient diet and injected daily with latamoxef (100 mg/kg, i.p.) were either treated or untreated with MK-4 for 7 days. Daily food intake, urine volume and feces weight were determined, and calcium concentration in these samples was measured. Calcium balance was calculated as the difference between calcium intake and urinary and fecal calcium excretion. Cumulative calcium balance in the vitamin K-deficient group treated with latamoxef was lower than that in normal rats; this balance was significantly improved by MK-4 (1 and 10 mg/kg, s.c.) administered for 7 days. Experiment 2: Rats were fed a vitamin K-deficient diet containing 4.6% sodium chloride for 6 weeks. MK-4 was administered as a dietary supplement. Forty-eight-hour calcium balance, determined once a week, was significantly reduced compared with that of normal rats after 3 and 5 weeks; the balance was restored dose-dependently by MK-4 administration (1 and 10 mg/kg). Experiment 3: Rats were subjected to the same experimental conditions as experiment 2 for 6 weeks, and intestinal calcium transport was determined using an everted gut-sac technique. Calcium transport was reduced by the high sodium, vitamin K-deficient diet, and this reduction was restored by MK-4 administration (10 mg/kg). These results suggest that MK-4 improves the reduced calcium balance by increasing intestinal calcium absorption in these rats.

The use of high ultrafiltration rates in haemodiafiltration (HDF) has been suggested for improving the clearance of small and large molecules. This strategy has become economically applicable with the development of safe techniques for on-line production of sterile infusate from dialysate, which enables us to infuse large substitution fluid volumes without further increasing the cost of sessions. The effect of increasing the ultrafiltration rate in HDF on electrolyte balance has not yet been evaluated. The aim of this study was to evaluate the effects of variations of the ultrafiltration rate on calcium kinetics in HDF using three different dialysate calcium concentrations. Since the increase in ultrafiltration rate augments the convective calcium loss, variations of intrasession calcium balance could result from modifications of the ultrafiltration rate. In the present study we found no significant variations in calcium balance and serum ionized calcium (iCa) levels during on-line HDF treatment when increasing the mean ultrafiltration rate from 60 to 100 ml/min in the presence of an adequate and corresponding increase in the infusion rate (from 2.5 to 5 l/h). During the balance studies, pretreatment serum iCa was on the average 1.32 mmol/l and weight loss 3.2 kg. Mean calcium loss during treatment was 2.8 and 3.3 mmol at infusion rates of 2.5 and 5 l/h with 1.63 mmol/l of calcium in both the dialysate and infusate; calcium loss rose to 5.9 and 11.2 mmol at infusion rates of 2.5 l/h and to 5.7 and 14.2 mmol at infusion rates of 5 l/h when the dialysate and infusate calcium was reduced respectively to 1.5 and 1.25 mmol/l.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone resorption inhibitors, such as bisphosphonates, are potentially useful in treatments aimed at increasing bone mass. Among bisphosphonates, tiludronate has proven efficacious in preventing bone loss in postmenopausal women. However, it is not clearly established whether bisphosphonates are more potent when given intermittently or continuously. We investigated the effects of tiludronate on (1) retinoid-stimulated bone resorption in thyroparathyroidectomized rats, (2) calcium balance in intact rats, and (3) bone mineral density (BMD) as measured by dual-energy x-ray absorptiometry at the levels of the lumbar spine, tail, and tibia in 6-month-old rats made osteoporotic by ovariectomy (OVX), in which an intermittent cyclic schedule of treatment was compared to continuous administration. Tiludronate induced a dose-dependent decrease in retinoid-stimulated bone resorption. It increased the intestinal absorption and body retention of calcium. In OVX rats it caused a time- and dose-dependent increase in BMD at the level of the three investigated sites, the effects being maintained for at least 8 weeks after the end of therapy. Continuous and intermittent cyclic regimens appeared to induce similar increases in BMD. These results indicate that tiludronate is efficacious in decreasing bone resorption and increasing calcium balance and bone mineral density in rats.

A frequent trouble in total parenteral nutrition is the occurrence of a negative calcium balance, due to reduction of calcium tubular reabsorption in acidosis. This condition could depend on acid metabolites raise, coming from degradation of nutritional amino acid mixtures. Authors have evaluated the effect of acetates addition to amino acid solutions on calcium balance. In fact the bicarbonate excess could reduce calcium urinary excretion. Thirty surgical patients have been treated. They were randomized according to acetates presence or absence in the administered solutions. In the acetate-treated group authors noted a raise in plasma bicarbonate and pH and a reduction in urinary calcium excretion. Adding acetates to amino acidic mixtures could reduce in total parenteral nutrition the risk of hypercalciuria and its related complications.

SUMMARY. Adult Gammarus pulex lose about 42% body calcium into solution over a 2–3-day period preceding the moult. A further 54% body calcium is lost with the exuviae, leaving c. 4% in the newly moulted animal. Nearly all of the body calcium in a stage A (post moult) animal is contained in the hepatopancreas and a transient increase in the calcium content of this tissue is seen in some individuals. The haemolymph calcium compartment is heavily depleted at this stage. In stage B animals the hepatopancreas calcium level has returned to, or even fallen below, the intermoult level while the haemolymph calcium concentration remains lower than in intermoult animals. Animals switch from a strongly negative calcium balance to a state of rapid calcium uptake immediately following moult. Uptake at 10°C proceeds at a rate of between 3 and 10 μmol g−1 h−1 depending on the calcium concentration of the external medium. The lower rate is found in starved animals in 0.1 mM calcium and this concentration is probably close to a minimum for the satisfactory restoration of body calcium. Recalcification is completed in 10–14 days in 0.1 mM calcium and is apparently enhanced by the presence of food in the form of a portion of oak leaf together with the cast exuviae. In 1.0 mM calcium the recalcification period is shortened to 3–4 days. This is considerably longer than the time recorded for French populations of this species (Vincent, 1969), although reasons for this are offered.

Methods for the measurement of calcium in the diet, urine and faeces for the performance of a calcium balance study are described, along with experiments on analytical procedures including recovery values. A means of calculating the inherent “technical error” in such a balance is given, and a method for determining the significance of any change in a patient's balance is described. These are illustrated by worked examples of data from a patient suffering from Paget's disease and one with osteoporosis before and after treatment with calcitonin.

The effect of low protein intake from plant sources on calcium excretions and calcium balance of seven young adults was investigated. The diets (four combinations of egg, groundnut and soyabean nitrogen) furnished 43 g protein (0.58 g protein/kg) and 550 mg calcium daily.

Calcium balance performance was evaluated in 130 normal perimenopausal women ages 35 to 50, studied on their usual, self-selected dietary calcium intakes. Two distinct balance methods were used, one based on customary intake and output measurements, and the other based on absorption and clearance of two simultaneously administered calcium isotopes. Both methods yielded essentially identical results. Under study conditions as closely approximating normal living as possible, these women averaged -24 and -31 mg Ca/day by the two balance methods (exclusive of unmeasured dermal losses). More significantly, there was a positive correlation between intake and balance, with women on higher self-selected intakes exhibiting more positive balance than women selecting lower intakes. The calcium intake predicted from our data which would be required to produce an average balance of zero was 1.241 g/day. This is significantly in excess of the current recommended dietary allowance for calcium. The implications and significance of this discrepancy are explored in detail.

The impact of estrogen deficiency on bone has been extensively studied in the female; however, the effects of androgen deficiency on calcium fluxes in males have been less well characterized. We investigated the effect of short-term, severe androgen deficiency on measures of calcium absorption and kinetics as well as on markers of bone turnover in males. To accomplish this, 11 healthy male volunteers were recruited (mean age 23.3 +/- 0.5 years [SEM], body mass index 25.3 +/- 0.8 kg/m2). They consumed a weight maintenance diet for at least 3 days prior to admission to our Research Unit, with a calcium intake of approximately 1200 mg/day. At baseline (D1), subjects received 42Ca intravenously as well as 44Ca PO mixed with milk or juice. A 29-h urine collection was begun and blood samples collected at frequent intervals for the measurement of the isotopic enrichment of 42Ca and 44Ca using thermal ionization mass spectrometry. Twice daily urine samples were collected for 5 days after the administration of the isotopes. A gonadotropin-releasing hormone agonist (Lupron) was given after D1, again 3 weeks later, and studies repeated identically 4 weeks (D2, n = 6) and 10 weeks from baseline (D3, n = 7) (two subjects completed three studies). Testosterone concentrations were markedly suppressed on both D2 and D3 (-95%, p < 0.006), whereas there were no detectable changes in growth hormone and insulin-like growth factor-1 concentrations. Urinary calcium excretion increased significantly after 4 weeks (43%, p = 0.0007) and 10 weeks (73%, p = 0.003) of sustained hypogonadism. Using a multicompartmental kinetic model, the contribution of oral calcium to the urinary losses was decreased by D3 (-41%, p = 0.01), yet the contribution of bone calcium to urine losses increased by 10 weeks (+11%, p = 0.01). There was a 21% decrease in bone calcium deposition (Vo+) by D3 (p < 0.05) with no significant change in bone resorption rates (Vo-). There was a significant correlation between the decrease in testosterone concentration and the increase in urinary calcium excretion, especially at 10 weeks (R2 = 0.84, p = 0.004). These kinetic changes were accompanied by a decrease in osteocalcin concentrations on D2, with improvements by D3. Urinary N telopeptide, a measure of bone resorption, also increased during the studies. In summary, profound hypogonadism in young males is associated with marked increases in urinary calcium losses, with a greater contribution of bone calcium to those losses and decreased kinetic markers of bone calcium deposition. We conclude that even short-term, severe deficiency in gonadal steroids can have profound negative effects on calcium and bone metabolism in males.

Calcium (Ca) supplements may be used to normalize Ca-balance changes but little is known about the effect of Ca supplements on Ca balance during hypokinesia (decreased kilometers per day). The aim of this study was to evaluate the effect of daily intakes of Ca supplements on Ca balance during hypokinesia (HK). Studies were done during 30 d of a pre-HK period and during 364 d of a HK period. Forty male athletes aged 23-26 yr were chosen as subjects. They were divided equally into four groups: unsupplemented ambulatory control subjects (UACS), unsupplemented hypokinetic subjects (UHKS), supplemented hypokinetic subjects (SHKS), and supplemented ambulatory control subjects (SACS). The SHKS and UHKS groups were kept under an average running distance of 0.7 km/d. In the SHKS and SACS groups supplemented with 35.0 mg Ca lactate/kg body weight. Fecal Ca loss, urinary excretion of Ca and phosphate (P), serum concentrations of ionized calcium (CaI) total Ca, P, and Ca balance, intact parathyroid hormone (iPTH) and 1,25 dihydroxyvitamin D (1,25(OH)2D), anthropometric characteristics and peak oxygen uptake were measured. Fecal Ca excretion, urinary Ca and P excretion, serum CaI, total Ca, and P concentration, and negative Ca balanced increased significantly (por = 0.01) in the SHKS and UHKS groups when compared with the SACS and UACS groups. Serum, urinary, and fecal Ca changes were much greater and appeared much faster in the SHKS group than in the UHKS group. Serum iPTH and 1,25 (OH)2 D, body weight, and peak oxygen uptake decreased significantly (por = 0.01) in the SHKS and UHKS groups when compared with the SACS and UACS groups. In contrast, the corresponding parameters remained stable in the SACS and UACS groups when compared with the baseline control values. It was concluded that during prolonged HK, urinary and fecal Ca excretion and serum Ca concentration increased significantly despite the presence of a negative Ca balance; thus, Ca supplements cannot be used to normalize negative Ca balance during prolonged HK.

The influence of the destruxin E, cyclodepsipeptidic mycotoxin produced by the filamentous entomopathogenic fungus Metarhizium anisopliae, on calcium fluxes and protein phosphorylation of in vitro cultivated lepidopteran cell lines have been studied. The use of the fluorescent calcium indicator Fura 2 AM did not show a fast increase in the level of cytosolic calcium in lepidopteran and human cell lines treated with dtx E. In contrast, 45Ca+2 assays detected a late but significant calcium influx in insect cells exposed to dtx E and A for at least 30 min. This effect was not inhibited by calcium channel blockers with the exception of nifedipine 25 microM. A viral treatment potentiated the effect of dtx E on calcium balance. Dtx E also induced a strong, fast (10 min), transient phosphorylation of high molecular weight (250 kDa) cellular proteins. The activation of phosphorylation was only partially inhibited by EDTA. This study provides the first direct evidence of dtx E influence on calcium fluxes and protein phosphorylation.

Abstract. Inulin, a dietary fibre found in the roots of many plants, has positive effects on health. It is particularly noteworthy due to its positive impact on calcium metabolism. Inulin has significant functions, such as improving calcium absorption through passive diffusion, bolstering calcium absorption via ion exchange and expanding the absorption surface of the colon by stimulating cell growth. In addition, inulin boosts calcium absorption by increasing calcium solubility, stimulating levels of calcium-binding protein expression and increasing useful microorganisms. It increases calbindin levels and stimulates transcellular active calcium transport. An inulin intake of least 8–10 g/day supports calcium absorption and total body bone mineral content/density in adolescents through its known mechanisms of action. It also significantly enhances calcium absorption and improves bone health in postmenopausal women and adult men. Sustained and sufficient inulin supplementation in adults has a positive effect on calcium metabolism and bone mineral density.

Two groups of Single Comb White Leghorn pullets, 4 months of age, were fed 1·85 and 2·70% calcium in the diet, respectively, for twelve consecutive periods, each consisting of 4 weeks.Records of egg production and egg weight were kept throughout the entire experiment for each hen. Calcium balance and egg-shell quality studies were conducted with 16 pullets for 5 consecutive days out of each 28-day period.A highly significant difference between the lots favouring the high-calcium birds was found in egg production, shell weight, and calcium retention. There were no significant differences between the lots in percentage calcium retention, food consumption, and body weight. The high-calcium group was shown to retain more calcium from the feed and excrete more calcium through eggs. Calcium retention and percentage calcium retention increased upon commencement of egg production to reach a maximum at the second period of production. Both remained fairly constant thereafter.The hens went into negative balance early in production and returned to positive balance during the later part of the first laying year. The return to positive balance could be explained by an increase in calcium retention and a decrease in egg production. There was no reduction in shell weight, or shell weight per unit surface area during the period covered by this trial.

Although receptors for somatostatin are found in bone cells, the effect of somatostatin analogs on calcium metabolism is unknown. The authors studied, in a metabolic ward, the effect of octreotide (a long-acting somatostatin analog) and a placebo in two 6-day calcium balance periods in 8 children with Duchenne muscular dystrophy. As expected, octreotide (2 μg/kg, subcutaneously, every 8 hours) reduced serum growth hormone and somatomedin (IGF-1) to levels found in growth hormone deflciency. Octreotide enhanced calcium retention by 30% (96 mg daily [P < 0.04]) in 7 boys for whom complete data (diet, urine, and fecal calcium) were available. In 6 children with urinary calcium excretion (UCa) greater than 50 mg daily, octreotide markedly lowered UCa, from 114 ± 23 mg daily to 61 ± 9 mg daily (P < 0.03). Calcium retention occurred in patients with or without initial hypercalciuria, but the higher the basal UCa, the greater was the inhibition by octreotide (r = 0.79; P < 0.03). Inactive, nonambulatory patients had a more pronounced response of UCa to octreotide (P < 0.02). Octreotide caused a mild, nonsignificant reduction in fecal calcium, with no major changes in serum calcium, phosphorus, parathyroid hormone, urinary excretion of sodium and potassium, or in creatinine clearance. Based on the current observations and the presence of receptors for somatostatin in bone cells, this hormone may have, at least on a short-term basis, an anabolic effect on calcium, perhaps favoring its deposition in bone.

We investigated factors affecting net transperitoneal calcium balance (Ca-BL) and the level of parathyroid hormone in relation to stepwise changes in serum calcium, by short PET (peritoneal equibrium test during 240 min: using 2000 ml of 2.5% dextrose dialysate containing 1.75 mmol/L Ca) in uremic patients undergoing stable CAPD. We calculated Ca-BL (mg/effluent/PET) of 244 effluents obtained from 90 patients receiving calcium carbonate as a phosphate binder without vitamin D supplementation. Their serum calcium level corrected with albumin (cSCa), alkaline phosphatase activity (ALP) and intact-PTH level was 9.7 +/- 0.9 mg/dl, 236 +/- 83 mIU/ml and 153.0 +/- 172.4 pg/ml, respectively. We proposed two statistic significant regression lines between Ca-BL and total drainage effluent volume (Ca-BL = 133X - 0.056: r = 0.981, P0.001), cSCa (Ca-BL = -12.9X + 123.6: r = 0.941, P0.01). Total drainage volume (TDV) and cSCa were two major factors affecting Ca-BL. A TDV level of 2430 ml/240 min-PET or more was required for positive Ca-BL in cases with 9.5-10.0 mg/dl of cSCa, using this linear regression analysis. A cSCa level of 9.6 mg/dl or more was also required for positive Ca-BL in cases with 2400-2600 ml/240min-PET. We also proposed a significant linear regression line between the intact-PTH level and cSCa (i-PTH = -90.5X + 1015.8, r = 0.973, P0.01). This line suggest that 200 pg/ml of intact PTH was obtained by 9.0 mg/dl or less of cSCa level in 90 CAPD uremic patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium is known to play an important role in the regulation of cellular processes as a secondary messenger in signal transduction to a specific response in all eucaryotic cells. Its messenger role is realized by transient changes in the Ca2+ cytosolic concentration induced by variety of external stimuli such as light, hormones and gravity. Recent findings claim the modifications in a calcium balance in plant cells in microgravity and under clinorotation reproducing partially the microgravity effect. Based on these data, the hypothesis is proposed that Ca2+ level changes can trigger the rearrangements in cell metabolism occurring in the conditions of altered gravity. However, the methods used in previous works permit only to determine the relative quantity of intracellular membrane-bound calcium and to observe the localization of free Ca2+. Therefore, it is of essential interest to measure the concentration of free calcium ions ([Ca2+]i) in plant cells under the influence of altered gravity. In this paper results from measurements of the [Ca2+]i in plant cells under clinorotation will be reviewed and discussed in an effort to examine their effectiveness, causes and consequences.

An acute effect of a single dose of 0.02 mg prolactin/100 g body weight administered intraperitoneally on distribution of absorbed calcium and the effect of daily subcutaneous injections of 0.25 mg prolactin/100 g body weight for 13 days on calcium balance were assessed in weaned, young, and mature female rats. The acute administration of prolactin failed to affect distribution of absorbed calcium at 2 h after instillation of test solution. In contrast, the daily injection of a lower dose of prolactin over 13 days significantly decreased fecal and urinary excretion of 45Ca, an index of absorbed calcium, in mature rats, while having no effect on muscle and tibial 45Ca contents. In young rats, in addition to a reduction in the urinary 45Ca excretion, prolactin decreased the gastrocnemius muscle total calcium content from 7.28 ± 0.37 to 5.58 ± 0.37 μmol/g dry weight (p

In postmenopausal osteoporotics, malabsorption of calcium is associated with reduced levels of serum 1,25-dihydroxyvitamin D. Metabolic studies have shown that calcium absorption can be normalized and calcium balance improved after administration of oral doses of synthetic 1,25-dihydroxyvitamin D3 (Rocaltrol) 0.25 micrograms twice daily. Further studies performed at two centers compared the effect of Rocaltrol 0.25 micrograms twice daily versus placebo on vertebral fracture rates in osteoporotics. A significant reduction in vertebral fracture rates was seen at the end of 1 year. Those patients who continued on Rocaltrol for a second and third year showed a progressive decrease in vertebral fractures. Rocaltrol, administered at a dose of 0.25 micrograms twice daily, seldom causes hypercalcuria or hypercalcemia in osteoporotic patients on a typical calcium intake of 700 to 800 mg/d. Careful measurements of renal function over a period of 3 years in patients treated with Rocaltrol, 0.25 micrograms twice daily, showed no deterioration in renal function. These data suggest that 1,25-dihydroxyvitamin D3 is a useful therapy in the management of patients with postmenopausal osteoporosis, particularly those who have malabsorption of calcium. We found that it improves calcium balance, reduces the vertebral fracture rate, and is safe to use provided that the dietary calcium is monitored and does not exceed 800 mg/d.

Summary: Twenty-six low birthweight infants with no differences in the neonatal status were allocated into three groups. Group A (10 infants), Group B (8 infants), and C (8 infants) received formulae with 2.4, 1.6, and 4.1 Calcium/Phosphate (Ca/Pi) ratio respectively. Formula C was supplemented with calcium lactate 800 mg/ kg/day, which yielded 12.7 ± 0.4 mg of Ca and 0.04 ± 0.002 mg of Mg per each 100 mg of salt (mean ± S.D.). The osmolality of the C formula before its administration was 361 ± 52 mOsm/kg. Balances (mean ± S.D.) from the first feeding up to a period of 3 days were obtained. The intestinal product before any feeding contained: Ca, 1.3 ± 0.6 mg/kg; Mg, 2.9 ± 1.5 mg/kg, and Pi, 1.5 ± 2.3 mg/kg. Calcium intake (mg/kg/day) was 89.7 ± 13.8 for formula A, 71.1 ± 12.5 for formula B, and 156.8 ± 19.8 for formula C. Their net retention (mg/kg/day) was 50.8 ± 15.9, 39.3 ± 12.8 (P < 0.05), and 105.2 ± 21.9 (p < 0.001) respectively. Net retention of Pi was comparable in the three groups (A, B and C) ranging 24.7–25.7 mg/kg/day. Small variations in intake are finely compensated by parallel urinary excretion (range 6.3–12.8 mg/kg/day). Magnesium absorption did not show differences among the three formulae. The evolution of plasmatic values for magnesium was fairly normal in the three groups. Phosphatemia was significantly (P < 0.01) lower in group A (lowest Pi containing formula) on the 3rd day. Patients on formula B (smaller Ca content) showed a mean blood calcium of 7.9 mg/dl, which was significantly lower than in the other groups. In two instances, blood calcium was lower than 6.9 mg/dl (Z = 6.32; P < 0.05). Net retention of calcium correlates positively with Ca/Pi ratio (r = 0.82) and with absolute Ca intake (r = 0.84). Calcium lactate supplementation did not modify acid base equilibrium, lactatemia nor digestive tolerance. Speculation: To prevent demineralization in the early postnatal period of preterm babies, the net retention of calcium could be improved more effectively by adding a calcium supplement to the formula rather than by decreasing its Pi content, even though both procedures lead to a comparable Ca/Pi quotient.

The anabolic effect of Formebolone on the retention of nitrogen, phosphorus and calcium in adult male volunteers was evaluated over a period of 21 days. The study was divided into a pre-dosc period to establish baseline data, a period where the drug was given daily followed by a third period after treatment had ceased to investigate whether the effects were in any way prolonged. Formebolone was well tolerated and showed a positive effect on nitrogen balance and bodyweight change in all subjects. The effects on calcium and phosphorus balance were less clear-cut but indicated increased retention of both elements.

SummaryEarlier papers in this series reported discrepancies between observed rates of Ca uptake by apple fruits and the rates calculated on the basis of a simple mass-flow hypothesis. Results from three further types of experiment designed to investigate these differences are presented. Rates of Ca deposition on filter papers suspended in the orchards were not adequate to explain the greater than expected rate of fruit Ca accumulation early in the season. Analyses of Ca distribution between different tissues of fruiting spurs provided no evidence for remobilization of Ca from the woody tissues of the spur as fruits developed. Different concentrations of CaCl2 were either perfused through stem segments or allowed to equilibrate with samples of fruit cortex at different dates during the season. In each case an apparent equilibrium concentration for the perfusing solution could be determined, at which the concentration of Ca did not change with perfusion. The equilibrium concentration was of the same order a...

Making use of an in vitro model of bovine aortic endothelial cell monolayers, the cell viability and changes of intracellukar calcium concentration of the preparation were submitted to hypoxia with or without reoxygenation. It was shown that the cell viability declined under hypoxia but increased under reoxygenation when the endothelial cells were incubated in calcium-free HBSS, as compared with control HBSS incubation. It was observed that a significant reduction of intracellular calcium from 99 to 69 nmol/L during 2 h of hypoxia, which was further decreased in Ca(2+)-free HBSS medium. After 4 h hypoxia followed by 40 min reoxygenation, [Ca2+]i recovered to the nomal concentration. It is speculated that the calcium homeostasis may be an important condition for cells to carry out normal function and either decrease or increase of [Ca2+]i may injury bovine aortic endothelial cells.

BENNION and Warren (1933) and Warren and Schnepel (1940) reported that shell thickness is reduced markedly if hens are subjected to high environmental temperatures. Their experiments further suggested that the depressing effect of high temperature is accentuated by high humidity. The mechanism or mechanisms which cause poor shell quality at high air temperatures are still not definitely established. Conrad (1939) found that blood calcium levels were reduced at high environmental temperatures. From this evidence Warren and Schnepel (1940) concluded that: “The decrease in shell thickness when the birds are subjected to high temperatures is probably due to a reduction in calcium content of the blood.” Warren and Schnepel (1940) also reported that hens kept at 95°F. consumed about 26% less feed than hens kept at 60°F. It is possible that this reduction of feed intake is at least partially responsible for the poor shell quality at high air temperatures. Finally, …

The present short review describes the physiological effects of rapid transient changes in cardiac extracellular ions (electrolytes) caused by the bolus of x-ray contrast medium (CM) during coronary angiography. The underlying hypothesis is that as the molecular and osmolal toxicities of modern CM is low, cardiac side-effects result mainly from secondary and biphasic ionic changes which occur during the initial washout phase and during the later re-introduction of blood. In particular the washout pattern for sodium (Na) and calcium (Ca) has great influence on cardiac function. Thus the Na-Ca exchange system of the cardiac cell membrane plays a pivotal role in controlling intracellular Ca and contractility during very brief coronary bolus injections of both nonionic and ionic CM. The nonionic dimer iodixanol is hyposmolal without an additive. Animal experiments demonstrate the value of taking myocarcardial Na-Ca relationships into careful consideration when adding ions to iodixanol and formulating an isotonic CM like Visipaque

Recent approaches to prevent and treat secondary hyperparathyroidism in dialysis patients include decreasing dialysate Ca content from 1.75 to 1.5 mM or lower. We have recently observed that by decreasing dialysate Ca to 1.25 mM a rise in intact parathormone serum levels occurs despite adequately controlled predialysis Ca and phosphate serum levels. In that study complementary treatment with high-dose 1 alpha(OH) vitamin D3 was required to suppress the parathormone. In the present study we aimed to assess the total Ca balance as well as the modifications in parathormone induced by the dialysis session in order to understand the reasons for which the rise in parathormone was induced.Fourteen HD patients treated with haemodiafiltration three times/week gave their informed consent for the study. They were distributed in two groups with identical treatment but for the dialysate Ca content which was 1.5 and 1.25 mM respectively and for the amount of oral CaCO3 received. Total and ionized Ca, phosphate, pH, and albumin as well as parathormone were measured in serum before and after dialysis and in the spent dialysate during two dialysis sessions.Serum ionized Ca (normalized to pH 7.4) did not change during 1.25 mM dialysate Ca and significantly increased with 1.5 mM (P0.001). The end-dialysis values being 1.25 +/- 0.02 and 1.38 +/- 0.02 mM respectively. Total Ca significantly decreased with 1.25 mM dialysate Ca (P0.04) and increased with 1.5 mM (P0.003), the end-dialysis values being 2.51 +/- 0.03 and 2.75 +/- 0.04 mM respectively. In the dialysate the difference in ionized Ca concentrations, fresh minus spent dialysate was -1.78 +/- 1.12 mmol/l (NS) and 4.26 +/- 1.47 mmol/l (P0.02) respectively for 1.25 and 1.5 mM dialysate Ca. The difference in total Ca concentrations, fresh minus spent dialysate was -0.1 +/- 0.01 mmol/l (P0.05) and -0.002 +/- 0.01 mmol/l (NS) respectively. Phosphate removal was higher in 1.25 mM dialysate-Ca-treated patients (40.4 +/- 1.75 mmol/session versus 34 +/- 1.3 mmol/session respectively, P0.015). The use of 1.25 mM dialysate Ca did not result in a change in serum parathormone, while the use of 1.5 mM resulted in a decrease of 43 +/- 15% (P0.02) in patients with marked hyperparathyroidism.Our data remind us of the difficulty in assessing Ca balances and identifies the phosphate content as one of the factors influencing the amount of ionized Ca in the dialysate. Although the long-term parathormone increase we observed using 1.25 mM dialysate Ca may well not be explained only by the acute intradialytic modifications, the negative Ca balance identified here (which was missed with the analysis of ionized Ca alone), and the lack of parathormone inhibition may participate in the relapse of hyperparathyroidism.

BACKGROUND Recent approaches to prevent and treat secondary hyperparathyroidism in dialysis patients include decreasing dialysate Ca content from 1.75 to 1.5 mM or lower. We have recently observed that by decreasing dialysate Ca to 1.25 mM a rise in intact parathormone serum levels occurs despite adequately controlled predialysis Ca and phosphate serum levels. In that study complementary treatment with high-dose 1 alpha(OH) vitamin D3 was required to suppress the parathormone. In the present study we aimed to assess the total Ca balance as well as the modifications in parathormone induced by the dialysis session in order to understand the reasons for which the rise in parathormone was induced. METHODS Fourteen HD patients treated with haemodiafiltration three times/week gave their informed consent for the study. They were distributed in two groups with identical treatment but for the dialysate Ca content which was 1.5 and 1.25 mM respectively and for the amount of oral CaCO3 received. Total and ionized Ca, phosphate, pH, and albumin as well as parathormone were measured in serum before and after dialysis and in the spent dialysate during two dialysis sessions. RESULTS Serum ionized Ca (normalized to pH 7.4) did not change during 1.25 mM dialysate Ca and significantly increased with 1.5 mM (P < 0.001). The end-dialysis values being 1.25 +/- 0.02 and 1.38 +/- 0.02 mM respectively. Total Ca significantly decreased with 1.25 mM dialysate Ca (P < 0.04) and increased with 1.5 mM (P < 0.003), the end-dialysis values being 2.51 +/- 0.03 and 2.75 +/- 0.04 mM respectively. In the dialysate the difference in ionized Ca concentrations, fresh minus spent dialysate was -1.78 +/- 1.12 mmol/l (NS) and 4.26 +/- 1.47 mmol/l (P < 0.02) respectively for 1.25 and 1.5 mM dialysate Ca. The difference in total Ca concentrations, fresh minus spent dialysate was -0.1 +/- 0.01 mmol/l (P < 0.05) and -0.002 +/- 0.01 mmol/l (NS) respectively. Phosphate removal was higher in 1.25 mM dialysate-Ca-treated patients (40.4 +/- 1.75 mmol/session versus 34 +/- 1.3 mmol/session respectively, P < 0.015). The use of 1.25 mM dialysate Ca did not result in a change in serum parathormone, while the use of 1.5 mM resulted in a decrease of 43 +/- 15% (P < 0.02) in patients with marked hyperparathyroidism. CONCLUSIONS Our data remind us of the difficulty in assessing Ca balances and identifies the phosphate content as one of the factors influencing the amount of ionized Ca in the dialysate. Although the long-term parathormone increase we observed using 1.25 mM dialysate Ca may well not be explained only by the acute intradialytic modifications, the negative Ca balance identified here (which was missed with the analysis of ionized Ca alone), and the lack of parathormone inhibition may participate in the relapse of hyperparathyroidism.

Changes in Ca(2+) content and flux, and the development of skin chloride cells in embryos and larvae of tilapia, Oreochromis mossambicus, were studied. Tilapia embryos hatched within 96h at an ambient temperature of 26-28°C. Total body Ca(2+) content was maintained at a constant level, about 4-8 nmol per individual, during embryonic development. However, a rapid increase in body Ca(2+) level was observed after hatching, 12.8 to 575.3 nmol per individual from day 1 to day 10 after hatching. A significant influx and efflux of Ca(2+) occurred during development, with the average influx rate for Ca(2+) increasing from 5.9 pmol mg(-1) h(-1) at 48h postfertilization to 47.8 pmol mg(-1) h(-1) at 1 day posthatching. The skin was proposed as the main site for Ca(2+) influx before the development of gills, and the increased Ca(2+) influx may be ascribed to gradual differentiation of skin surface and chloride cells during embryonic development. Ca(2+) efflux was 16-56 pmol mg(-1) h(-1) in 1-day-old larvae. The resulting net influx of Ca(2+), 10-12 pmol mg(-1) h(-1), accounted for the increased Ca(2+) content after hatching. When comparing the measured and estimated ratios of efflux and influx, active transport was suggested to be involved in the uptake of Ca(2+). Chloride cells, which may be responsible for the active uptake of Ca(2+), started to differentiate in the skin of embryos 48h after fertilization, and the density of chloride cells increased following the development. A possibility of active transport for Ca(2+) in early developmental stages of tilapia is suggested.

RATIONALE AND OBJECTIVES. During coronary arteriography the blood is replaced for a short period of time with a contrast medium (CM) solution. The CM may cause a risk of arrhythmias and ventricular fibrillation (VF). Previous investigations have shown that the addition of small amounts of sodium (10-30 mmol/L) to nonionic CM may decrease the risk of VF from these media. Calcium addition to nonionic CM may reduce a negative inotropic effect. In the current investigation, the changed risk of VF from nonionic CM with 19 to 30 mmol/L NaCl was studied when the media also contained calcium or calcium and magnesium. METHODS. An isolated rabbit heart model was used. The risk of arrhythmias and VF from the nonionic monomer iohexol and the nonionic dimer iodixanol containing 19 to 30 mmol/L NaCl with 0 to 2.5 mmol/L calcium as CaCl2 was studied. In the series with iodixanol, 0 to 0.95 mmol/L MgCl2 also was added to the solutions with sodium and calcium, but the role of magnesium was not especially evaluated in the investigation. RESULTS. Nonionic CM with small amounts of NaCl (19-30 mmol/L), without calcium or with calcium at the level of 0.05 to 0.3 mmol/L, caused the lowest risk of VF. When relatively higher additions of calcium reached the physiologic concentration of 2.5 mmol/L, the CM caused a greater risk of arrhythmias and VF. CONCLUSIONS. When calcium is added to a nonionic CM, the concentration of calcium must be balanced against the NaCl concentration to minimize the risk of VF. Excessive calcium concentration will increase the risk of VF. (Less)

The use of citrate, through reversible binding of calcium, has become the preferred choice for anticoagulation in continuous renal replacement therapy in the critically ill patient. Though generally considered as very efficacious in acute kidney injury, this type of anticoagulation can cause acid–base disorders as well as citrate accumulation and overload, phenomena which have been well described. The purpose of this narrative review is to provide an overview of some other, non-anticoagulation effects of citrate chelation during its use as anticoagulant. We highlight the effects seen on the calcium balance and hormonal status, phosphate and magnesium balance, as well as oxidative stress resulting from these unapparent effects. As most of these data on these non-anticoagulation effects have been obtained in small observational studies, new and larger studies documenting both short- and long-term effects should be undertaken. Subsequent future guidelines for citrate-based continuous renal replacement therapy should take not only the metabolic but also these unapparent effects into account.