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There is controversy about the choice of dialysate calcium concentration (DCa), with strong arguments both in favor of and against the use of a low or high DCa, as they can both be potentially harmful. Evidence suggests that calcium mass balance is positive with a DCa 3.5 mEq/L, negative or neutral with the use of DCa 2.5 mEq/L, whereas both positive and negative balances have been observed with the use of DCa 3.0 mEq/L. Overall, the use of DCa >2.5 mEq/L is usually associated with an increase in serum calcium level and a decrease in serum PTH level and use of lower vitamin D analogue dose, with the opposite effects usually observed with the use of lower DCa. Most of the available evidence is from small-sized and crossover studies; hence, evidence should be regarded with caution and applied in a patient-specific manner. As there are a lot of significant unanswered questions regarding calcium balance and the optimal DCa in hemodialysis patients, further high-quality research is needed to clarify many still unclear aspects of calcium homeostasis and balance in these patients. In conclusion, with the existing evidence the choice of DCa needs to be individualized and contextualized in the setting of each patient's calcium balance needs and homeostatic response, taking also into account oral calcium intake (dietary and medicinal), any other relevant therapy administered, such as vitamin D analogues, the type of renal mineral bone disorder, and associated cardiovascular comorbidity.

Aim To assess the efficacy, safety and calcium balance of a membrane based regional citrate anticoagulation plasma exchange protocol. Methods This was an observational, prospective, single centre study of membrane separation plasma exchange using regional citrate anticoagulation. It was performed using a fixed dose pre-filter citrate infusion that was based on the plasma flow rate. Patients received a post filter calcium infusion that was modified during treatment based on systemic ionized calcium monitoring. Post filter ionized calcium was not assessed. Safety and efficacy were assessed by extraction of clinical events and laboratory data contemporaneously recorded in electronic health records. Results Thirty-six sessions in five patients were performed. No patients developed symptomatic hypocalcaemia, and no patient had a recorded ionized calcium below 0.81 mmol/L. Filter clotting occurred in two sessions. The mean net calcium gained was 9.6 ± 1.8 mmol per session. Conclusion Regional citrate anticoagulated membrane separation plasma exchange can be performed safely and effectively without the need for post filter ionized calcium monitoring. The algorithm employed resulted in a net calcium gain.

Purpose of Review The kidneys play a critical role in the balance between the internal milieu and external environment. Kidney failure is known to disrupt a number of homeostatic mechanisms that control serum calcium and normal bone metabolism. However, our understanding of calcium balance throughout the stages of chronic kidney disease is limited and the concept of balance itself, especially with a cation as complex as calcium, is often misunderstood. Both negative and positive calcium balance have important implications in patients with chronic kidney disease, where negative balance may increase risk of osteoporosis and fracture and positive balance may increase risk of vascular calcification and cardiovascular events. Here, we examine the state of current knowledge about calcium balance in adults throughout the stages of chronic kidney disease and discuss recommendations for clinical strategies to maintain balance as well as future research needs in this area. Recent Findings Recent calcium balance studies in adult patients with chronic kidney disease show that neutral calcium balance is achieved with calcium intake near the recommended daily allowance. Increases in calcium through diet or supplements cause high positive calcium balance, which may put patients at risk for vascular calcification. However, heterogeneity in calcium balance exists among these patients. Summary Given the available calcium balance data in this population, it appears clinically prudent to aim for recommended calcium intakes around 1000 mg/day to achieve neutral calcium balance and avoid adverse effects of either negative or positive calcium balance. Assessment of patients’ dietary calcium intake could further equip clinicians to make individualized recommendations for meeting recommended intakes.

Huntington's disease (HD) is a neurodegenerative, dominantly inherited genetic disease caused by expansion of the polyglutamine tract in the huntingtin gene. At the cellular level, HD is characterized by the accumulation of mutant huntingtin protein in brain cells, resulting in the development of the HD phenotype, which includes mental disorders, decreased cognitive abilities, and progressive motor impairments in the form of chorea. Despite numerous studies, no unambigous connection between the accumulation of mutant protein and selective death of striatal neurons has yet been established. Recent studies have shown impairments in the calcium homeostasis in striatal neurons in HD. These cells are extremely sensitive to changes in the cytoplasmic concentration of calcium and its excessive increase leads to their death. One of the possible ways to normalize the balance of calcium in striatal neurons is through the sigma 1 receptor (S1R), which act as a calcium sensor that also exhibits modulating chaperone activity upon the cell stress observed during the development of many neurodegenerative diseases. The fact that S1R is a ligand-operated protein makes it a new promising molecular target for the development of drug therapy of HD based on the agonists of this receptor.

We studied the role of calcium-regulating structures of slow- (m. soleus, SOL) and fast-twitch (m. extensor digitorum longus, EDL) skeletal muscles of rats during adaptation to exhausting physical activity and the possibility of modulating this adaptation with decaffeinated green tea extract. It was established that EDL adaptation is mainly aimed at Са2+ elimination from the sarcoplasm by Са-ATPase and its retention in the reticulum by calsequestrin. Administration of green tea extract increased endurance due to involvement of slow-twitch muscles whose adaptation is associated with enhanced expression of all the studied genes responsible for the regulation of Ca2+ balance.

Tomato fruits of high quality and yield are of interest to greenhouse growers. As potassium (K) and calcium (Ca) have been associated with fruit quality, we studied the effect of the balance between such cations and the electrical conductivity (EC) on fruit yield and quality. Plants were fertigated with K (Kext) and Ca (Caext) balances in the nutrient solution varying from 0.54–1.22 and 0.69–1.44 at ECs of 2.3 ± 0.1 dS m−1 and 2.7 ± 0.1 dS m−1, respectively. Optimum balance for fruit yield was 0.82–0.85, and it was associated with high fruit K internal (Kint) concentration (~ 200 mmol kg−1). Higher EC increased firmness when the balance was ≤ 1.00, with the optimum at 0.85; firmness was correlated with Caint when EC was 2.3 dS m−1; however, at 2.7 dS m−1, increasing Kext increased firmness and intensified the effect of Caext. Increasing a* values were associated with high lycopene and uniform maturation when that balance was 0.82 and 1.00 at low and high EC, respectively. Highest a* values were observed when Kint in the fruit was ~ 200 mmol kg−1, while 91 to 130 mmol kg−1 were associated with lower a* values. Fruits contained higher starch (+ 20%), total (+ 12%), and reducing sugars (+ 29%) at high EC. The optimum K and Ca balance, 0.82–0.85, is independent of their concentration and was associated with high yield and firmness, improved fruit color, and increased lycopene and sugar concentrations.

Ethnopharmacological relevance Fructus Ligustri Lucidi (FLL) is an edible herb with anti-osteoporotic activity, yet whether and how the aqueous extract of this herb affect calcium metabolism in preservation of bone quality remain unclear. Aim of the study To investigate the effects of FLL aqueous extract on calcium balance and short-chain fatty acids (SCFAs) production in ovariectomized (OVX) rats. Materials and methods OVX rats were daily and orally administrated with FLL aqueous extract (3.5 g/kg) for 14 weeks. The levels of N-terminal propeptide of type I collagen (PINP) and C-terminal telopeptide of type I collagen (CTx-I) in rat serum were evaluated by ELISA assays. The concentration of calcium in serum, urine, and feces were determined by biochemical assays. Bone quality was determined by Micro-CT, a three-point bending assay, and Fourier Transform Infrared (FTIR) Spectrometry. The expressions of Calbindin D28K and Calcium-sensing receptor (CaSR) in kidney as well as the Vitamin D receptor (VDR), the transient receptor potential vanilloid receptor 6 (TRPV6), Calbindin D9k in the duodenum were measured by immunohistochemistry, western blotting, or real-time PCR. The short-chain fatty acids (SCFAs) levels in the feces of the cecum were tested by gas chromatograghy. Results The administration of FLL to OVX rats resulted in a significant improvement in bone mineral density and biomechanical strength as well as in maintaining bone microstructures and material quality. Meanwhile, the decreased levels of PINP and increased levels of CTx-I in OVX rats were restored by FLL treatment. Additionally, FLL treatment increased calcium absorption, upregulated VDR, TRPV6, Calbindin D9k expressions in the duodenum, Calbindin D28K in kidney, and down-regulated CaSR expression in the kidney, as well as enhanced SCFAs levels in the feces of OVX rats. Conclusions FLL aqueous extract may preserve bone quality through regulation of the calcium balance and intestinal SCFAs production in OVX rats. This offers translational value of FLL into osteoporosis clinical trial.

Background Online hemodiafiltration (oHDF) is increasingly used in children; we treated 28 children since 2009, adapting this technique to pediatric patients. Methods In this service evaluation audit, we assessed plasma electrolytes to evaluate the evolution of total (tCa) and ionized (iCa) during a session, as well as dialysate calcium (dCa) concentrations. Results Using a 1.25 mmol Ca/L-dialysate, both tCa and iCa decreased during the session, with iCa falling below 1.1 mmol/L in 4/5 patients. In contrast, using a 1.5 mmol Ca/L-dialysate, iCa remained normal in all patients. Major discrepancies were observed between the expected and the measured dCa: 1.25 vs. 1.01 (0.83–1.04), and 1.5 vs. 1.47 (0.85–1.75) mmol/L, respectively (results presented as median [range]). These differences were explained by the modality of reconstituting dialysate: increasing bicarbonates and/or decreasing sodium requested in the dialysate decreases calcium extraction from the acid preparation. Proof of concept was given when requesting in an “ex-vivo” setting modifications in the requested sodium and bicarbonate in dialysate directly on the Fresenius machine. Conclusion Nephrologists should be aware that “high bicarbonate and/or low sodium” requirements in oHDF decrease calcium in the dialysate.

Agnieszka Makowka, Michal Nowicki Department of Nephrology, Hypertension and Kidney Transplantation, Medical University of Lodz, Lodz, PolandCorrespondence: Michal NowickiDepartment of Nephrology, Hypertension and Kidney Transplantation, Medical University of Lodz, Central University Hospital, Pomorska Str 251, Lodz, 92-213, PolandTel +48 42 2014400Fax +48 42 2014401Email nefro@wp.plObjective: Opposite to lanthanum carbonate (LC), sevelamer hydrochloride (SH) may increase intestinal calcium absorption. The study compared the effects of LC and SH on serum and urine phosphate and calcium, and on hormones regulating mineral-bone metabolism.Patients and Methods: A prospective randomized crossover study included 34 patients with eGFR < 60 mL/min. A single oral dose of LC (1,000 mg) or SH (2,400 mg) was administered in random order 15 minutes after a standardized meal fortified with 5 g calcium carbonate. Serum calcium, phosphate, and parathormone were measured before and 3, 6, 12, and 24 hours after each medication. Bone alkaline phosphatase (BAP), sclerostin, calcitriol, and FGF-23 were measured at baseline and after 12 and 24 hours. A 24-hour calcium and phosphate excretion was measured after each drug.Results: Serum calcium increased 3 and 6 hours after SH then returned to baseline. After LC calcium was unchanged for up to 3 hours then transiently increased and eventually returned to baseline. The area under curve (AUC) of serum calcium for 12 hours after SH was larger than after LC (p=0.04). Serum phosphate decreased after each drug with a nadir 3 hours post-SH and 6 hours post-LC. AUC of serum phosphate was similar after both medications. PTH decreased transiently after both drugs. BAP did not change. FGF-23 was constant for the first 12 hours but later decreased after each drug.Conclusion: A 2,400 mg SH and 1,000 mg LC are similarly effective in lowering serum phosphate in CKD, but LC induce in less intestinal calcium absorption after a meal. The trial was registered on February 23, 2018 in the clinicaltrial.gov database – NCT03451019.Keywords: calcium, chronic kidney disease – mineral bone disorder, hyperphosphatemia, phosphate-binders, PTH

Introduction: To assess the safety, efficacy, and calcium flux of an accelerated algorithm for regional citrate anticoagulation in membrane-based plasma exchange. Methods: This was an observational study in patients receiving citrate anticoagulated, membrane-based plasma exchange at the Canberra Hospital between July 2017 and May 2020. Data were collected prospectively using an electronic medical record and compared to data from our previous published algorithm. Results: There were 134 plasma exchange sessions performed during the observational period. Circuit clotting occurred in 4 sessions, and 1 session was affected by symptomatic hypocalcaemia. A systemic ionized calcium Conclusion: An accelerated algorithm for regional citrate anticoagulation achieves substantial time saving while maintaining efficacy and safety. The 4 episodes of systemic ionized calcium

1. Mean linear attenuation coefficients for trabecular bone (T) in the distal radius and total absorption coefficients (TA) in the radial mid-shafts of 22 patients with crush fracture osteoporosis were measured serially for a year by using computed tomography. After approximately 6 months, each patient was admitted to a metabolic ward for an 18-day calcium balance study. 2. The rate of change (trend) in trabecular bone (T) in the distal radius was a better predictor of calcium balance than the trend in mid-shaft cortical bone (TA). 3. The scatter in the regressions of the trends of T and TA on calcium balance could be accounted for by known methodological uncertainties.

Calcium regulation in sturgeon is of special interest because they are a representative of the ancient fishes possessing mainly cartilaginous skeletons and a supposedly low calcium demand. The present study aimed to characterize the effect of a chronic absence of dietary calcium and the effect of parathyroid hormone-related protein (PTHrPA) (1-34) ( 7 ) on calcium balance in juvenile sturgeon ( Acipenser naccarii). At rest, sturgeon juveniles are in net positive calcium balance, since whole body calcium uptake is significantly higher than efflux and calcium accumulates in the body. To study the importance of dietary calcium, the sturgeon were kept on a calcium-free diet for 8 wk. This manipulation impaired growth as measured by failure to gain weight or increase in length and indicates that dietary calcium is important for growth in sturgeon. An increased whole body calcium uptake partially compensated dietary calcium deficiency and was associated with increased gill chloride cell number in lamellae and filaments in parallel with increased gill Na+K+-ATPase activity. In addition, a single injection of piscine PTHrP(1-34) significantly increased whole body calcium uptake and decreased whole body calcium efflux. Administration of PTHrP significantly increased circulating plasma calcium 4–24 h postinjection. The increase in net calcium transport and increased plasma levels of calcium is consistent with the actions of a hypercalcemic factor. It would appear that the sturgeon rely on calcium for growth and tightly regulate calcium transport. The action in calcium balance is consistent with PTHrP acting as a hypercalcemic factor in sturgeon.

Protein and calcium metabolisms interact at multiple levels. It is well known that an increase in the protein content of the diet causes an increase of the calcium concentration in the urine. However, the exact consequences of protein intake on the calcium economy are debated. Indeed, there are two explanations for increased calciuria: increased calcium absorption or increased bone resorption. Currently, there is no clear answer; however, there is increasing evidence that protein intake is not harmful to bone. In fact, an increased protein intake would probably be beneficial for bone. This chapter reviews the different aspects of the protein–calcium interaction and discusses the proposed mechanisms. The consequences for health are also considered, especially on bone strength and kidney-stone formation.

Previous research documented that furosemide negatively impacted calcium balance for 3 days but did not determine when calcium balance returned to baseline. This study hypothesized that furosemide's impact on calcium would return to control values before 7 days post-administration. Ten mature geldings were assigned to either control (CON, n = 5) or treatment (FUR, n = 5) for the first of two 8-day total collections in crossover design. Treatment horses received one administration of furosemide (1 mg/kg, IV). A 10% sample of pooled faeces and urine from each day was kept. Calcium concentrations in hay, faeces and urine were determined by an atomic absorption spectrophotometer. Data were analysed using mixed-model-repeated measures ANOVA to determine influence of day and treatment. For urine output, FUR urinated twice as much during the 24 hr after administration than CON (p .001). Horses in FUR excreted more urinary calcium 24-hr post-administration as compared to CON (9.3 ± 1.0 and 4.2 ± 1.0 g, respectively; p .001). Calcium balance in FUR was more negative on day 1 than day 3 (p .05). Faecal calcium concentrations remained the same from day 1 to day 7 in CON (6.3 ± 1.3 and 5.5 ± 1.3 g/kg, respectively; p .10) but were lower in FUR on day 7 as compared to day 1 (4.8 ± 1.3 and 7.3 ± 1.3 g/kg, respectively; p .001), indicating a potential mechanism to restore calcium balance. These findings corroborate previous studies on furosemide and calcium balance and provide evidence for a possible mechanism to recover net calcium losses after furosemide administration. Since calcium balance returns to baseline in 3 days and previous results have examined frequent, long-term use, furosemide may not negatively impact bone mineral content even if used over long periods.

Aim. To evaluate the state of bone tissue in comparison with calcium balance, to clarify the risk for fracture development in women of different age groups. METHODS. 92 females aged 19 to 89 years were examined clinically with densitometry of lumbar spine and femoral neck and measuring the concentration of total calcium in the blood. RESULTS. In females younger than 50 years decreased bone density according to Z-score was revealed in 30% of cases, among patients with its normal values significant trend to bone rarefaction (-2.0 SD Z-score ≤-1.5 SD) was registered with the same rate. In the group of females older than 50 years osteopenia was revealed in 46.3% of cases and osteoporosis - in 42.7%, while more significant decrease in bone mineral density was found in the lumbar spine. Past medical history of fractures increased the rate of osteoporosis by 18%. In females older than 50 years compared to younger patients a significant increase of blood calcium concentration was revealed. Besides, statistically significant increase of its level was noted in cases of fractures in the past and osteoporosis. The revealed changes of bone tissue in females below 50 years of age are indicative of increased risk of osteoporosis development in the future. CONCLUSION. High prevalence of osteoporosis and osteopenia is revealed in the examined patients older than 50 years, and bone mineral density parameters were significantly inversely correlated with calcemia; hence, blood calcium level can be one of the criteria of bone tissue state and in combination with other risk factors for osteoporosis should be taken into account during periodic health examination of females older than 50 years.

Editor's Note: This paper is one of the first suggesting that idiapathic osteoporosis may be n disorder of calcium metabolism for which increased intakes calcium mas be preventative.

The aim of this study was to evaluate the effect of Fructus Ligustri Lucidi (FLL), a kidney-tonifying Chinese herbal medicine, on the biochemical markers of bone turnover, calcium metabolism and balance in osteoporotic rat model developed by ovariectomy. Four weeks after surgical operation, animals were randomly assigned to one of the four treatments for 14 weeks: sham-operated control treated with vehicle (sham, n=8), ovariectomized group treated with vehicle (OVX, n=8), OVX group treated with 17beta-estradiol (E(2), n=10, 2 microg/kg/d) and OVX group treated with FLL extracts (FLL, n=10, 550 mg/kg/d). Serum osteocalcin and urinary deoxypyridinoline levels were upregulated in rats in response to OVX, suggesting that the bone turnover rate was accelerated in these animals. Treatment of OVX rats with FLL extract could prevent OVX-induced increase in bone turnover by suppression of both serum osteocalcin (p0.05, vs. OVX) and urinary deoxypyridinoline (p0.05, vs. OVX) levels. In addition, FLL extract could prevent OVX-induced loss of calcium in rats by increasing the intestinal calcium absorption rate (p0.01, vs. OVX), suppressing urinary Ca excretion (p0.05, vs. OVX) as well as increasing bone calcium content (p0.05, vs. OVX). Our study is the first to report that FLL can modulate bone turnover and calcium balance in OVX rats and it might be a potential candidate for prevention and treatment of postmenopausal osteoporosis.

Objective: The purpose of this study was to examine the effects of vitamin K2 administration on calcium balance and bone mass in young rats fed a normal or low calcium di

Calcium supplements for prevention and treatment of mineral and bone disorders in chronic kidney disease (CKD) have been alternately praised and damned. Clinical evidence in favor of either attitude has been lacking. The calcium balance study by Spiegel and Brady in patients with late stage 3 and stage 4 CKD suggests that CKD subjects ingesting 2000mg of elemental calcium per day are in marked positive balance. Methodological limitations such as unproven steady state warrant caution and confirmatory studies.

The effect of dietary lentils on calcium balance was evaluated in nine healthy male subjects. The Control and Experimental (+ 130 g dry lentils) diets were each fed for three weeks in a cross-over design. Study diets were matched to subjects' usual calcium and energy intakes, and balanced for protein and phytate. Complete fecal collections were made for all weeks and 24-hour urine collections were made in Week 3 of each period. Calcium balance was maintained during both the Control (0.4 ± 0.8 mmol/day, mean ± SEM) and Experimental periods (− 0.6 ± 0.9 mmol/day); fecal calcium remained unchanged (28.5 ± 1.7 mmol/day, 29.7 ± 1.5 mmol/day, respectively). Urinary excretion, however, varied from Control to Experimental periods for the following: calcium decreased from 5.43 ± 0.44 to 4.53 ± 0.41 mmol/day (P

Prior to the advent of calcitriol therapy, haemodialysis (HD) patients were often in negative calcium (Ca) balance between dialyses because of severely impaired Ca absorption [1] that led to the recommendation of dialysate inlet Ca concentration (CdiCa++) 3.0–3.5 mEq/L, higher than plasma concentration [2]. Over the past 25 years since the advent of calcitriol, virtually all haemodialysis patients absorbed a substantial portion of dietary and phosphate binder calcium ingested between dialyses and yet CdiCa++ 3.0 mEq/L has continued to be widely used. The total Ca absorbed between dialyses (CaAbsT) must be removed by the dialyser (JdCaT) to achieve net zero Ca mass balance over the dialysis cycle and prevent chronic Ca overload that likely contributes to the high rate of vascular calcification in haemodialysis patients [3–5]. From this perspective, it follows that the CdiCa++ prescribed should result in neutral Ca mass balance and thus total Ca removed during dialysis (JdCa++), the sum of diffusive (JDiffCa++) and convective Ca++ (JConvCa++) removal, should equal CaAbs in accordance with

Study of morphometric parameters of podocyte foot processes showed that the increase of parathyroid hormone blood level causes dilatation of podocyte foot processes resulting from accumulation of calcium in the cells. Influence of the hormone on filtration processes in glomeruli as a result of its effect on podocytes is discussed.

A research work was undertaken to evaluate the feeding effects of di-calcium phosphate (DCP) on calcium balance and body condition score of dairy cows fed Napier grass. The trial was conducted in the village Alokdiar of Shajadpur upazilla under Sirajgonj district. Twenty crossbred lactating dairy cows of 320 ±15.5 kg live weight were used for the trial. Animals were equally and randomly allocated into four groups, T0 (Napier+concentrate), T1 (Napier+concentrate+100g DCP), T2 (Napier+concentrate+150g DCP) and T3 (Napier+concentrate+200g DCP). Total DMI did not differ significantly (p>0.05) among the groups but highly significant differences (p0.05) was found in DM in feces (%), DM in feces (kg/d) and milk production (L) among the treatment groups except urine excretion. There was a linear increase of body condition score (BCS) with DCP (T1, T2 and T3), but BCS was linearly declined in non DCP diet (T0). Diets with 150g DCP may be suggested for optimizing Calcium balance and body condition score of dairy cows fed Napier grasses.DOI: http://dx.doi.org/10.3329/bjas.v43i3.21648 Bang. J. Anim. Sci. 2014. 43 (3): 197-201

A dialysate containing a calcium concentration of 1.75 mmol/L has been the standard in CAPD for a long time. This concentration was chosen to achieve a positive calcium balance to suppress hyperparathyroidism. In the measurement of peritoneal calcium mass transfer, conflicting results have been published, with positive and negative calcium balances reported. These differences have been explained by differences in the filtration rate, and a negative correlation between the filtration rate and the peritoneal calcium mass transfer can be found. Whereas nearly all patients in this study had a negative calcium balance using a glucose solution of 3.86%, a wide variation was found for the 1.36% glucose solution. There were several patients who had a positive calcium balance despite a positive filtration rate. The explanation for this finding lay in differences in serum concentrations of calcium, and especially differences in the size of the total exchangeable calcium pool that contains the plasma calcium compartment. A negative correlation between peritoneal calcium balance and the size of the total exchangeable calcium pool could be demonstrated. This finding may explain the differences in the peritoneal calcium flux reported in the literature. As an enlargement of the exchangeable calcium pool correlates with the progression of vascular calcification, therapeutic efforts should be directed toward prevention of an enlargement of this pool.

Calcium is an important nutrient but also contributes to the texture, taste and functionality of most dairy products. The balance between micellar and free calcium in curd and serum phase during direct acidification of bovine milk was studied by changing organic acid type, pH and acidification temperature. Concentration of free calcium increased with decreasing pH and increasing temperature. Citric acid was more efficient than lactic acid at lowering free calcium concentration, while temperature effect was larger for acidification with lactic acid. These findings are rationalized by the stronger binding of calcium to citrate compared to lactate with an almost athermal binding for citrate and an endothermal binding for lactate. Curd yield decreased by decreasing pH as solubilization of colloidal calcium phosphate causes loss of minerals into the serum phase decreasing the concentration of both calcium and phosphate left in the curd, while acidification temperature had little effect on curd yield. These results are important to improve yield and tailor the properties and functionality of dairy products, such as for example Mozzarella cheese.

BACKGROUND Low intakes of calcium are associated with an increased risk of both osteoporosis and cardiovascular disease. OBJECTIVE To provide new estimates of the average calcium requirement for men and women, we determined the dietary calcium intake required to maintain neutral calcium balance. DESIGN Calcium balance data [calcium intake -(fecal calcium + urinary calcium)] were collected from 155 subjects [women: n = 73; weight: 77.1 +/- 18.5 kg; age: 47.0 +/- 18.5 y (range: 20-75 y); men: n = 82; weight: 76.6 +/- 12.5 kg; age: 28.2 +/- 7.7 y (range: 19-64 y)] who participated in 19 feeding studies conducted in a metabolic unit. Balance data from the final 6-12 d of each dietary period (minimum length:18 d) of each study (1-9 observations per subject) were analyzed. Data were excluded if individual intakes of magnesium, copper, iron, phosphorus, or zinc fell below the estimated average requirements or exceeded the 99 th percentile of usual intakes from the 1994 Continuing Survey of Food Intakes by Individuals (for iron, above the upper limit). Daily intakes of calcium ranged between 415 and 1740 mg. The relation between intake and output was examined by fitting random coefficient models. Coefficients were included to test for sex and age differences. RESULTS The models predicted a neutral calcium balance [defined as calcium output (Y) equal to calcium intake (C)] at intakes of 741 mg/d [95% prediction interval (PI): 507, 1035; Y = 148.29 + 0.80C], 9.4 mg kg body wt(-1) d(-1) [95% PI: 6.4, 12.9; Y = 1.44 + 0.85C], or 0.28 mg kcal(-1) d(-1) [95% PI: 0.19, 0.38; Y = 0.051 + 0.816C]. Neither age nor sex affected the estimates when calcium intakes were expressed as mg/d or as mg kg body wt(-1) d(-1). CONCLUSION The findings suggest that the calcium requirement for men and women is lower than previously estimated.

Backgrounds. Calcium (Ca) and bone metabolism in continuous ambulatory peritoneal dialysis (CAPD) and hemodialysis (HD) patients show a remarkable difference depending on dialysis modalities. The levels of serum Ca and phosphate (P) in HD patients fluctuate contributing to the intermittent and rapid removal of plasma solute unlike in CAPD. Characteristics of plasma solute transport in automated peritoneal dialysis (APD) patients are resembled with that in HD. The purpose of the present study was to examine the difference of transperitoneal Ca removal between APD and CAPD anuric patients.Subjects and Methods. Twenty-three APD anuric patients were enrolled in this study. Biochemical parameters responsible for transperitoneal Ca removal in 24-hour and 4-hour peritoneal effluents were analyzed on CAPD and APD.Results. Transperitoneal Ca removal on APD was smaller compared with that on CAPD. The Ca removal was related to the ultrafiltration during short-time dwell. Decrease of the Ca removal during NPD induced by short-time dialysate dwell caused negative or small Ca removal in APD patients. The levels of intact PTH were increased at the end of PET.Conclusion. It appears that short-time dwell and frequent dialysate exchanging might suppress the transperitoneal Ca removal in anuric APD patients.

25 Pag., 5 Tabl. The definitive version is available at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1522-2624, Experiments to evaluate the effect of in-season calcium (Ca) sprays on late-season peach (Prunus persica L. Batsch cv. Calrico) were carried out for a 2-year period. Calcium formulations (0.5% and 1.0% in 2008 and only 0.5% tested in 2009) supplied either as CaCl2 or Ca propionate in combination with two or three adjuvants (0.05% of the nonionic surfactants Tween 20 and Break Thru, and 0.5% carboxymethylcellulose, CMC) were sprayed four to five times over the growing season. Peach mesocarp and endocarp Ca concentrations were determined on a 15-day basis from the beginning of May until the end of June. Further tissue analyses were performed at harvest. A decreasing trend in fruit Ca concentrations over the growing season was always observed regardless of the Ca treatments. Both in 2008 and 2009, significant tissue Ca increments associated with the application of Ca-containing sprays in combination with adjuvants were only observed in June, which may be coincident with the period of pit hardening. In 2008, both at harvest and after cold storage, the total soluble-solids concentration (° Brix) of fruits supplied with Ca propionate (0.5% and 1.0% Ca) was always lower as compared to the rest of treatments. The application of multiple Ca-containing sprays increased firmness at harvest and after cold storage, especially when CaCl2 was the active ingredient used. Supplying the adjuvants Tween 20 and CMC increased fruit acidity both at harvest and after cold storage. Evaluation of the development of physiological disorders after cold storage (2 weeks at 0°C) indicated a lower susceptibility of Ca-treated fruits to internal browning. Fruits treated with multiple CaCl2-, CMC-, and Break Thru®-containing sprays during the growing season were significantly less prone to the development of chilling injuries as compared to untreated peaches., Dr. V. Fernández is supported by a “Torres Quevedo contract” (MICINN-PTQ) co-financed by the European Social Fund. Work was financed by AGL2009-08501/AGR (Programa Nacional de Proyectos de Investigación Fundamental), and INIA (PET2007-09-C5), cofinanced by the European Social Fund.

The response of calciotropic hormones and bone turnover to exercise and immobilization was examined by the measurement of calcium balance, bone turnover indexes, levels of parathyroid hormone, nephrogenous adenosine 3',5'-cyclic monophosphate (cAMP), and 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] weekly for 6 wk in three groups of rats: control, exercise trained, and immobilized. Early in the experiment, increases were observed in excretion of urinary calcium, hydroxyproline, and in serum alkaline phosphatase after both exercise and immobilization. It was not until the latter part of the experimental period that changes were observed in nephrogenous cAMP and intestinal absorption efficiency of calcium. In the fasting state, the exercise group had a drop in serum calcium and phosphate and a rise in nephrogenous cAMP and serum 1,25(OH)2D3 compared with the control group. The exercised animals experienced an increase in bone mass, whereas the immobilized animals had a decline in bone mass. Thus exercise stimulates bone growth, resulting in an increased demand for minerals that is satisfied by an increase in serum 1,25(OH)2D3 levels and increased intestinal absorption of calcium. The increase in calcium absorption suppresses parathyroid hormone production (nephrogenous cAMP) in the exercised animal. Immobilization resulted in increased bone resorption that suppressed parathyroid hormone, nephrogenous cAMP, and the intestinal absorption of calcium.

Calcium balances performed on 519 individuals from birth to 30 years of age, derived from 34 published reports, were pooled by age group and the relationship between intake and balance for each group was compared at both extremes of the intake range. At all ages, from infancy through the young adult years, balance values tended to flatten and become constant at higher intakes, while at lower intakes balance was invariably highly correlated with intake. Threshold intakes and balances were estimated by fitting the data to a two-component, split, linear-regression model. The threshold values at which balance no longer rose with intake exceeded the US recommended dietary allowances for calcium for all the age groups concerned.

Calcium flux and mode of uptake were investigated in an underground dwelling mole-rat, Cryptomys damarensis, fed diets of varying Ca content. The amount of dietary Ca positively influenced the amounts ingested, absorbed and retained. The linear relationship between ingested and absorbed Ca was significantly (P less than 0.001) correlated, implying that this process is nonsaturable. When mole-rats were fed a diet low in Ca, apparent fractional absorption of Ca was high (85.88%). This increased still further when the diet was changed to a food of greater Ca content (96.13%, carrots; 96.97%, gemsbok cucumber). Mineral homeostasis is regulated at the intestinal level in most mammals. Regardless of dietary Ca content, uptake of 45Ca (examined via the everted gut sac technique) was passive, confirming that absorption is via a nonsaturable process. Plasma Ca concentrations were not tightly regulated, yet when fed the diet with the highest Ca content, mole-rats were not hypercalcemic. Regardless of diets, Ca apparent fractional retention was positive, and approached physiological maxima (greater than 97%). Cryptomys damarensis, in using highly efficient modes of mineral uptake and retention, is therefore capable of fully exploiting the limited food resources of their arid ecotope.

Contains fulltext : 35554.pdf ( ) (Open Access) Juvenile gilthead sea bream were exposed to diluted seawater (2.5 per thousand salinity; DSW) for 3 h or, in a second experiment, acclimated to DSW and fed a control or calcium-deficient diet for 30 days. Branchial Ca(2+) influx, drinking rate and plasma calcium levels were assessed. Sea bream plasma parathyroid hormone related protein (sPTHrP) was measured, and mRNAs of pthrp, its main receptor, pth1r, and the calcium-sensing receptor (casr) were quantified in osmoregulatory tissues and the pituitary gland. When calcium is limited in water or diet, sea bream maintain calcium balance; however, both plasma Ca(2+) and plasma sPTHrP concentrations were lower when calcium was restricted in both water and diet. Positive correlations between plasma sPTHrP and plasma Ca(2+) (R(2)=0.30, N=39, P

The nature and mechanism of calcium complexation with human serum components in the presence of silicone rubber were assessed in in vitro model experiments. Silicone rubber samples were incubated for 67 h in serum of both physiologic calcium concentrations and induced hypercalcemic levels. Physiologic calcium incubation decreased the intrinsic and nth binding site association constants by factors of 2 and 4, respectively, from initial serum values. Incubation with silicone rubber did not change the association constants. Hypercalcemia incubation lowered the intrinsic and nth binding site association constants by 39 and 61%, respectively. Polymer incubation increased the intrinsic association constant and decreased the number of binding sites by a factor of 2. With initial binding site association constants unperturbed by incubation and Hill coefficients equivalent to 1, complexation was non-cooperative and binding sites were considered to be identical and independent. Both Scatchard and Hill plots show nonlinearity for the polymer incubation case giving two distinct linear regions. This is indicative of cooperative binding for incubation with polymer; the Hill coefficient for the physiologic calcium concentration range was 0.97, while the coefficient for the hypercalcemic calcium range was 6.

To determine whether during hypokinesia (diminished movement) periodic physical exercise affects calcium (Ca(2+)) balance and Ca(2+) loss.Studies were conducted on 30 physically healthy male volunteers during the preexperimental period of 30 days and the experimental period of 364 days. They were equally divided into three groups: active control subjects (ACS), hypokinetic subjects (HKS), and periodic training subjects (PTS). The ACS group ran an average distance of 9.3+/-1.2 km/d; the HKS group walked an average distance of 1.3+/-0.2 km/d; and PTS group walked and ran average distances of 1.3+/-0.2 km/d and 9.2+/-1.2 km/d for 5 and 2 days per week, respectively.Serum Ca(2+) level, fecal and urine Ca(2+) loss, and Ca(2+) imbalance increased (P0.05) in the PTS and HKS groups compared with their preexperimental levels and the values in their respective ACS group. The serum Ca(2+) concentration, urine and fecal Ca(2+) loss, and Ca(2+) imbalance increased more (P0.05) in the PTS group than in the HKS group.During hypokinesia, Ca(2+) imbalance is more evident with than without physical exercise and Ca(2+) loss is exacerbated more with higher than lower Ca(2+) imbalance.

Background: Additional calcium is required during lactation, and several calcium regulatory factors are involved in calcium balance. In lactating rural women who have marginal nutrition and consume a high-fiber diet, negative calcium balance may be expected. Objective: We evaluated calcium balance and its association with potential calcium regulatory factors in lactating, rural Mexican women who had marginal nutrition and consumed a high-fiber diet. Design: This cross-sectional study included women at 1, 3, 6, and 12 mo of lactation (L1, L3, L6, and L12 groups) and women who had weaned their infants (W group). Age-matched, nonlactating women (NL group) were also included. Calcium balance and concentrations of calcium regulatory factors were determined. Correlation analysis was performed by using data from all of the lactating women. Results: Calcium balance in the L1, L3, and L6 groups was negative and was significantly different (P < 0.05) from that in the W and NL groups. Serum parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D [1,25-(OH) 2 D] concentrations were significantly higher (P < 0.05) in the W group than in the L and NL groups. Calcium balance was positively associated with serum estradiol concentrations (r = 0.58, P < 0.05) and negatively associated with serum 1,25-(OH) 2 D concentrations (r = -0.52, P < 0.05). Breast-milk calcium concentrations correlated positively with serum PTH-related peptide (PTHrP) concentrations (r = 0.51, P < 0.05) and negatively with serum estradiol concentrations (r = -0.57, P < 0.05). Conclusions: Negative calcium balance was observed during lactation in rural Mexican women who consumed a high-fiber diet. Furthermore, the data suggest that the hormones estradiol and PTHrP are involved in the regulation of calcium balance and of the calcium content of milk during lactation.

The dietary acid load created by the typical Western diet may adversely impact the skeleton by disrupting calcium metabolism. Whether neutralizing dietary acid with alkaline potassium salts results in sustained improvements in calcium balance remains controversial. In this randomized, double-blind, placebo-controlled study, 52 men and women (mean age 65.2 ± 6.2 years) were randomly assigned to potassium citrate 60 mmol/d, 90 mmol/d, or placebo daily with measurements of bone turnover markers, net acid excretion, and calcium metabolism, including intestinal fractional calcium absorption and calcium balance, obtained at baseline and at 6 months. At 6 months, net acid excretion was significantly lower in both treatment groups compared to placebo and it was negative, meaning subjects' dietary acid was completely neutralized (-11.3 mmol/d on 60 mmol/d; -29.5 mmol/d on 90 mmol/d, p < 0.001 compared to placebo). At 6 months, 24-hour urine calcium was significantly reduced in persons taking potassium citrate 60 mmol/d (-46 ± 15.9 mg/d) and 90 mmol/d (-59 ± 31.6 mg/d) compared with placebo (p < 0.01). Fractional calcium absorption was not changed by potassium citrate supplementation. Net calcium balance was significantly improved in participants taking potassium citrate 90 mmol/d compared to placebo (142 ± 80 mg/d on 90 mmol/d versus -80 ± 54 mg/d on placebo; p = 0.02). Calcium balance was also improved on potassium citrate 60 mmol/d, but this did not reach statistical significance (p = 0.18). Serum C-telopeptide decreased significantly in both potassium citrate groups compared to placebo (-34.6 ± 39.1 ng/L on 90 mmol/d, p = 0.05; -71.6 ± 40.7 ng/L on 60 mmol/d, p = 0.02) whereas bone-specific alkaline phosphatase did not change. Intact parathyroid hormone was significantly decreased in the 90 mmol/d group (p = 0.01). Readily available, safe, and easily administered in an oral form, potassium citrate has the potential to improve skeletal health. Longer-term trials with definitive outcomes such as bone density and fracture are needed.

This chapter discusses the role of calcium balance in aging. Calcium balance is the resultant of several interacting forces, including nutrition, hormonal status, disuse, and general involution. Minimization of the structural impact of a negative calcium balance (that is, a depleted skeleton) requires a multifaceted approach, including, but not limited to, an adequate calcium intake. Because calcium utilization is inefficient even during growth; and becomes more so with age; calcium intake requirements are high, and rise with age. Intakes of calcium for healthy elderly persons should be in the range of 1400–1600 mg/day, and patients with osteoporosis being treated with bone active agents may need substantially more to realize the full benefit of their antiosteoporosis therapies. The goal of a high calcium intake in the elderly is both to make certain that inadequate calcium is not compounding the other negative factors influencing the aging skeleton. and to support any bone-building potential that may reside in current and future antiosteoporosis therapies.

Calcium balance in chronic kidney disease is poorly understood as calcium deficiency is a stimulus for secondary hyperparathyroidism and consequent bone loss while calcium excess promotes extraosseous calcifications. To help resolve this, we evaluated calcium balance in normal individuals and in patients with chronic kidney disease (CKD) on daily diets containing 800 and 2000 mg elemental calcium. Both normal individuals and patients with late stage 3 and stage 4 CKD were in slightly negative to neutral calcium balance on the 800-mg calcium diet. Normal individuals were in modest positive calcium balance on the 2000-mg diet, while patients with CKD on the same diet were in marked positive calcium balance at least over the 9 days of study; and significantly greater than the normal individuals. Increased calcium intake significantly decreased 1,25-dihydroxy-vitamin D and intact parathyroid hormone levels but did not alter the serum calcium concentration. Thus, our findings have important implications for both preventing calcium deficiency and loading in individuals with late stage 3 and stage 4 CKD.

The acid-ash hypothesis posits that protein and grain foods, with a low potassium intake, produce a diet acid load, net acid excretion (NAE), increased urine calcium, and release of calcium from the skeleton, leading to osteoporosis. The objectives of this meta-analysis were to assess the effect of changes in NAE, by manipulation of healthy adult subjects' acid-base intakes, on urine calcium, calcium balance, and a marker of bone metabolism, N-telopeptides. This meta-analysis was limited to studies that used superior methodological quality for the study of calcium metabolism. We systematically searched the literature and included studies if subjects were randomized to the interventions and followed the recommendations of the Institute of Medicine's Panel on Calcium and Related Nutrients for calcium studies. Five of 16 studies met the inclusion criteria. The studies altered the amount and/or type of protein. Despite a significant linear relationship between an increase in NAE and urinary calcium (p < 0.0001), there was no relationship between a change of NAE and a change of calcium balance (p = 0.38; power = 94%). There was no relationship between a change of NAE and a change in the marker of bone metabolism, N-telopeptides (p = 0.95). In conclusion, this meta-analysis does not support the concept that the calciuria associated with higher NAE reflects a net loss of whole body calcium. There is no evidence from superior quality balance studies that increasing the diet acid load promotes skeletal bone mineral loss or osteoporosis. Changes of urine calcium do not accurately represent calcium balance. Promotion of the "alkaline diet" to prevent calcium loss is not justified.

The debate on the most adequate dialysate calcium concentration for intermittent haemodialysis therapy is ongoing. There is probably no one optimal concentration. In general, one would like to maintain a neutral calcium balance in adult haemodialysis patients. However, a slightly negative balance may be preferable to avoid soft-tissue calcium accumulation in face of net calcium loss from the bone with ageing. The problem with measurements of calcium balance is that they are generally imprecise, as are estimations of total body calcium and its distribution in various compartments, unless done with labour-intensive methods and great care. The choice of the dialysate calcium will depend on several factors, including parathyroid and vitamin D status, type and severity of concomitant bone disease, presence or absence of arterial calcification, dietary habits, drug treatment and dialysis modality. Ideally the dialysate calcium would be adapted to each patient's needs. This is not feasible, however, in most dialysis settings and neither is it cost-effective. From a practical point of view, a relatively high dialysate calcium concentration in the range of of 1.50-1.75 mmol/L (3.0-3.5 mEq/L) should probably be preferred in haemodialysis patients with high serum PTH levels who are not prescribed calcium-based phosphate binders or high doses of active vitamin D sterols, and in those who are receiving a calcimimetic. In those who are treated with high doses of calcium-based binders and/or active vitamin D derivatives or who have a very low serum PTH level, the optimal dialysate calcium concentration is probably lower, in the range of 1.25-1.50 mmol/L (2.50-3.0 mEq/L). In the present pro/con debate about the optimal dialysate calcium concentration used for the haemodialysis session, we have accepted to defend the viewpoint that a low calcium concentration may do more harm than benefit in many patients. This viewpoint is opposite to that taken by Gotch [1]. He argues that since calcitriol and other active vitamin D derivatives have become available virtually all haemodialysis patients are in positive calcium balance. We would like to take issue with this statement and warn against the indiscriminate use of a low calcium dialysate in all patients receiving haemodialysis therapy.

45Ca kinetics and calcium balance studies allow for the simultaneous determination of calcium movement in the intestines, kidneys and bones. Since the flow of minerals in each of these organs depends on those in other organs, it is important to evaluate calcium movement as a whole throughout the entire body. Morphological methods can be used to evaluate local bone formation and resorption microscopically within defined windows. However, bone remodeling does not proceed equally in every part of the skeleton, and local events tend to be misread as general phenomena. Although variables such as bone formation and resorption obtained in 45Ca kinetics and calcium balance studies tell nothing about the location of these events, and the concept of compartments can be somewhat difficult to understand, this method is still useful for obtaining quite reliable results compared to those obtained by other methods. Our review describes the concept of the compartment model and explains the pertinent methods in comparison with other methods.

Objective: Fructus ligustri lucidi (FLL) is a widely used herb in China that is classically included in antiaging formulas for the treatment of age-related symptoms. Our laboratory previously showed that FLL could regulate calcium balance in young ovariectomized (OVX) rats. In the present study, we aimed to determine whether FLL could regulate calcium balance in aged OVX rats and to study the potential mechanisms that mediate its action in vivo. Design: Aged OVX rats were orally administered an ethanol extract of FLL and its vehicle and fed with diets containing different levels of calcium [low calcium diet (LCD), 0.1% Ca; medium calcium diet (MCD), 0.6% Ca; and high calcium diet (HCD), 1.2% Ca] for 12 weeks. Results: Significant reductions in urinary and fecal calcium excretion were found in the FLL-treated animals, resulting in a significant induction of calcium retention in rats fed with the MCD and HCD. FLL treatment significantly increased the serum 1,25-dihydroxyvitamin D 3 level and slightly decreased the serum parathyroid hormone level in OVX rats fed with the MCD and HCD. When OVX rats were challenged by LCD, the inductions of serum parathyroid hormone and 1,25-dihydroxyvitamin D 3 were decreased by FLL administration. FLL treatment significantly up-regulated duodenal vitamin D receptor and calcium transport protein 1 mRNA expression in rats fed with the HCD. FLL treatment reduced the expression of renal vitamin D receptor and 25-hydroxyvitamin D-24-hydroxylase mRNA in OVX rats fed with the LCD and MCD. Conclusions: Twelve weeks of FLL treatment could reduce calcium loss, modulate the parathyroid hormone-vitamin D axis, and increase vitamin D-dependent calcium transport in aged OVX rats, suggesting that FLL might be useful as an alternative medicine for improving calcium balance in postmenopausal women.

Few calcium balance data are available from young children on which to base dietary recommendations.The objective of the study was to evaluate the relation between calcium intake and balance in healthy children aged 1-4 y consuming typical American diets.Subjects were assigned to a diet with nutrient intakes similar to those of their usual diet. Calcium absorption was assessed by using a dual-tracer stable-isotope technique. Endogenous fecal excretion was measured in a subset of children, and net calcium balance was calculated.Mean calcium intake was 551 mg/d (range: 124-983 mg/d), and mean (+/-SEM) calcium retention was 161 +/- 17 mg/d. Both linear and nonlinear modeling of balance data showed that a calcium intake of approximately 470 mg/d led to calcium retention of 140 mg/d, which is the amount that meets expected bone growth needs in children of this age. No evidence was found that calcium intakes of 800 to 900 mg/d reached the threshold intake beyond which no additional increase in calcium retention would occur.Bone growth needs in 1-4-y-old children following American diets are met by a daily calcium intake of approximately 470 mg/d, which suggests that the current Adequate Intake of 500 mg/d is close to the actual Estimated Average Requirement. The benefits and risks of higher calcium intakes consistent with threshold values should be evaluated in a controlled trial before those intakes could be used as a basis for dietary recommendations.