Characterization of percutaneous absorption of calcium, magnesium, and potentially toxic elements in two tailored sulfurous therapeutic peloids: a comprehensive in vitro pilot study.

Pelotherapy treatments in thermal spas, which utilize peloids composed of clay minerals mixed with saltwater or mineral-medicinal water, can have various effects on spa users, ranging from therapeutic to potential adverse reactions. Despite the widespread use of peloids, comprehensive information on the penetration and permeation of essential and potentially toxic elements into deeper layers of the skin during pelotherapy is limited. Understanding the concentrations of these elements is crucial for evaluating therapeutic benefits and ensuring safety. This study investigates the in vitro availability and absorption of calcium, magnesium, and potentially toxic elements in two peloids, considering their formulation matrix. To replicate the pelotherapy methodology, an in vitro permeation experiment was conducted using a vertical diffusion chamber (Franz cells) and a biological system with human skin membranes from five Caucasian women, age range between 25 and 51 years. The experiment involved heating the peloids to 45℃. The results emphasize the possible transport properties of chemical elements in peloids, providing valuable information related to potential therapeutic efficacy and safety considerations. Despite no apparent differences between peloids' chemical composition, the method identified permeation variations among chemical elements. The methodology employed in this study adheres to the guidelines outlined by OECD for analyzing skin absorption through an in vitro approach. Furthermore, it aligns with the associated OECD guidance document for conducting skin absorption studies. The replicability of this methodology not only facilitates the analysis of peloids pre-formulation but also provides a robust means to evaluate the effectiveness of therapeutic elements during topical administration, particularly those with potential toxicity concerns.

Angiopep-2-modified calcium arsenite-loaded liposomes for targeted and pH-responsive delivery for anti-glioma therapy.

The blood-brain barrier (BBB) is the most critical obstacle in the treatment of central nervous system disorders, such as glioma, the most typical type of brain tumor. To overcome the BBB and enhance drug-penetration abilities, we used angiopep-2-modified liposomes to deliver arsenic trioxide (ATO) across the BBB, targeting the glioma. Angiopep-2-modified calcium arsenite-loaded liposomes (A2-PEG-LP@CaAs), with uniformly distributed hydrodynamic diameter (96.75 ± 0.57 nm), were prepared using the acetate gradient method with high drug-loading capacity (7.13 ± 0.72%) and entrapment efficiency (54.30 ± 9.81%). In the acid tumor microenvironment, arsenic was responsively released, thereby exerting an anti-glioma effect. The anti-glioma effect of A2-PEG-LP@CaAs was investigated both in vitro and in vivo. As a result, A2-PEG-LP@CaAs exhibited a potent, targeted anti-glioma effect mediated by the lipoprotein receptor-related (LRP) receptor, which is overexpressed in both the BBB and glioma. Therefore, A2-PEG-LP@CaAs could dramatically promote the anti-glioma effect of ATO, as a promising strategy for glioma therapy.

Role of mitochondria in the differential action of sodium deoxycholate and ursodeoxycholic acid on rat duodenum.

Sodium deoxycholate (NaDOC) inhibits the intestinal Ca2+ absorption and ursodeoxycholic acid (UDCA) stimulates it. The aim of this study was to determine whether NaDOC and UDCA produce differential effects on the redox state of duodenal mitochondria altering the Krebs cycle and the electron transport chain (ETC) functioning, which could lead to perturbations in the mitochondrial dynamics and biogenesis. Rat intestinal mitochondria were isolated from untreated and treated animals with either NaDOC, UDCA, or both. Krebs cycle enzymes, ETC components, ATP synthase, and mitochondrial dynamics and biogenesis markers were determined. NaDOC decreased isocitrate dehydrogenase (ICDH) and malate dehydrogenase activities affecting the ETC and ATP synthesis. NaDOC also induced oxidative stress and increased the superoxide dismutase activity and impaired the mitochondrial biogenesis and functionality. UDCA increased the activities of ICDH and complex II of ETC. The combination of both bile acids conserved the functional activities of Krebs cycle enzymes, ETC components, oxidative phosphorylation, and mitochondrial biogenesis. In conclusion, the inhibitory effect of NaDOC on intestinal Ca2+ absorption is mediated by mitochondrial dysfunction, which is avoided by UDCA. The stimulatory effect of UDCA alone is associated with amelioration of mitochondrial functioning. This knowledge could improve treatment of diseases that affect the intestinal Ca2+ absorption.

Relationship of the mobile forms of calcium and strontium in soils with their accumulation in meadow plants in the area of Kashin-Beck endemia.

This study was aimed at assessment of strontium and calcium mobility in soils and their accumulation with plants in the areas endemic for Kashin-Beck disease in Eastern Transbaikalia. The strontium and calcium mobility levels were determined using the method of sequential chemical extraction for 7 samples of meadow soils collected from the endemic region and 7 soil samples taken from conditionally control sites. To measure the Ca and Sr levels in the soil and plant samples, XRF analysis and AAS were used. The increased strontium level in the meadow soils of the endemic areas is accompanied by the element's higher mobility. The highest strontium yield was observed in the course of soil extraction using 1 M ammonium acetate, while the soils taken from the control sites gave lower amounts of the trace element. Furthermore, there is a positive correlation between the amount of the strontium extracted and its content in plants (r = + 0.86 - 0.98). At the sequential chemical extraction of calcium from the soils using the above method, the calcium yield was maximal in the ammonium acetate fraction (background sites) and in ammonium acetate and 6 M HCl fractions (endemic areas). The correlation between the amount of the calcium extracted in 1 M ammonium acetate and the macroelement levels found in plants was + 0.968. In addition, a peculiarly high accumulation of strontium in various willow species as compared to other meadow plants was revealed for the first time ever. Thus, the work introduces new data into the trace element biogeochemistry and environmental monitoring.

Effect of Adding a Galacto-Oligosaccharides/Fructo-Oligosaccharides (GOS/FOS®) Mixture to a Normal and Low Calcium Diet, on Calcium Absorption and Bone Health in Ovariectomy-Induced Osteopenic Rats.

Menopause is associated with bone loss. Prebiotics increase Ca, inorganic phosphorus (Pi), and Mg absorption, improving bone health. These increases would supply an extra amount of minerals, decreasing bone resorption and possibly reversing ovariectomy-induced bone loss. The present experimental study sought to evaluate the effect of adding a prebiotic GOS/FOS® mixture to a normal or a low Ca diet on Ca, Pi, and Mg absorption, in osteopenic rats. Four groups of n = 8 rats each were OVX, and 8 rats were SHAM operated. All rats were fed a commercial diet for 45 days. They were then fed one of the following diet for 45 days: C-0.5%: SHAM fed AIN 93 M containing 0.5%Ca; O-0.5% and O-0.3%: OVX rats fed AIN 93 M, containing 0.5% or 0.3%Ca, respectively; GF-0.5% and GF-0.3%: OVX rats fed AIN 93 M, containing 0.5% or 0.3%Ca+ 2.5% GOS/FOS®, respectively. At the end of the experimental time point, Ca, P, and MgAbs% was significantly higher in GF-0.5% and GF-0.3% as compared to the remaining groups (p < 0.01). Irrespective of diet Ca content, CTX decreased whereas femur Ca and P content, tibia BV/TV and GPC.Th, lumbar spine and proximal tibia BMD, bone strength, bone stiffness, and elastic modulus increased in the GF-0.5% and GF-0.3% groups as compared to O-0.5% and O-0.3%, respectively (p < 0.05). This prebiotic mixture would be a useful tool to prevent the increase in bone loss associated with menopause and aging.

Functional characterisation of naturally occurring mutations in human melanopsin.

Melanopsin is a blue light-sensitive opsin photopigment involved in a range of non-image forming behaviours, including circadian photoentrainment and the pupil light response. Many naturally occurring genetic variants exist within the human melanopsin gene (OPN4), yet it remains unclear how these variants affect melanopsin protein function and downstream physiological responses to light. Here, we have used bioinformatic analysis and in vitro expression systems to determine the functional phenotypes of missense human OPN4 variants. From 1242 human OPN4 variants collated in the NCBI Short Genetic Variation database (dbSNP), we identified 96 that lead to non-synonymous amino acid substitutions. These 96 missense mutations were screened using sequence alignment and comparative approaches to select 16 potentially deleterious variants for functional characterisation using calcium imaging of melanopsin-driven light responses in HEK293T cells. We identify several previously uncharacterised OPN4 mutations with altered functional properties, including attenuated or abolished light responses, as well as variants demonstrating abnormal response kinetics. These data provide valuable insight into the structure-function relationships of human melanopsin, including several key functional residues of the melanopsin protein. The identification of melanopsin variants with significantly altered function may serve to detect individuals with disrupted melanopsin-based light perception, and potentially highlight those at increased risk of sleep disturbance, circadian dysfunction, and visual abnormalities.

Solving the calcium gluconate shortage in real-time: Mistakes made and lessons learned.

PURPOSE: During a national shortage of calcium gluconate, we switched to calcium chloride for routine supplementation for peripheral blood stem cell (PBSC) collections. Subsequently, we analyzed the postprocedure ionized calcium level, as we aimed for an equivalent result compared to before the shortage. METHODS: Pharmacy representatives helped us to find an "equivalent" substitute for calcium gluconate at 46.5 mEq in 500 mL normal saline, infused at 100 mL/hour. After instituting a presumably comparable protocol using calcium chloride (40.8 mEq in 250 mL normal saline at a rate of 100 mL/hour), we reviewed ionized calcium results post-PBSC procedures to compare with those obtained with calcium gluconate. Having noticed a difference in the mean values, we adjusted the rate of calcium chloride to reach our desired outcome. RESULTS: Twenty-seven procedures were analyzed on 15 unique patients. We used the Spectra OPTIA with a whole blood: anticoagulant ratio of 13:1. Ionized calcium levels post-PBSC collection with the first calcium chloride protocol were significantly higher (P = 0.003) in nine patients treated. Subsequently, we decreased the calcium chloride infusion rate to 75 mL/hour and achieved similar mean levels to calcium gluconate (P = 0.382). CONCLUSION: Changes in replacement fluids for apheresis procedures can be complex, particularly when dealing with electrolytes that could be clinically significant at critically high or low levels. Once we recognized the need to take into account the amount of elemental calcium infused, we achieved the desired postprocedure ionized calcium results. This study can serve as a lesson for future shortages of infusions used during apheresis procedures.

Exploring the role of soil geochemistry on Mn and Ca uptake on 75-year-old mine spoils in western Massachusetts, USA.

Manganese pollution to plants, soils, and streams from Mn-rich mine spoils is a global and persistent issue. Some former mining sites can be revegetated readily while others struggle to support plants. We explored Mn in plants and soils following 75 years of soil development and reforestation of a pine-northern hardwood forest at the former Betts Mine in western Massachusetts, USA. We studied soils on four Mn-rich mine spoils and at two control sites: an undisturbed location adjacent to the mine and on a non-Mn mineral bearing rock formation to determine if soil conditions have influenced the uptake of Mn and Ca by vegetation. We collected mid-season foliage from five dominant canopy trees and four common understory plants and excavated three soil pits at each site during July 2018. We found that control sites had lower total Mn (980 ± 140 µg g-1) in their soils than on the mine spoil sites (5580 ± 2050 µg g-1). Our soil data indicated that < 1% of total Mn was strong acid extractable at mine spoil soils and control sites. Surprisingly, the canopy trees established on mine spoils at the Betts Mine had equal to or lower foliar Mn concentrations (840 ± 149 µg g-1) and lower Mn/Ca ratios (0.3 ± 0.1 mol mol-1) than at control sites (1667 ± 270 µg g-1; 1.1 ± 0.2 mol mol-1), refuting our hypothesis of mine spoils driving highest Mn uptake. Soil pH and physicochemical properties suggest Mn primarily exists within primary minerals or form insoluble oxides at the mine spoil sites. Our results suggest higher Ca availability and pH in soils likely reduced Mn uptake and promoted reforestation of the mine spoils.

Stimulation of intestinal calcium absorption by orally administrated vitamin D3 compounds: a prospective open-label randomized trial in osteoporosis.

Intestinal fractional calcium absorption (FCA) was assessed before and after vitamin D3 treatment. Serum 1,25(OH)2D concentration was significantly increased by plain vitamin D3 and reduced by eldecalcitol. The 1α hydroxyl calcidiol and eldecalcitol treatments increased FCA, which may be induced through direct stimulation of vitamin D receptors in the intestine. INTRODUCTION: To assess the effects of vitamin D3 compounds on intestinal FCA and calcium-regulating hormones in post-menopausal osteoporosis, a randomized open-label prospective study was conducted. METHODS: Forty eligible patients were allocated randomly into four groups: eldecalcitol (ELD; 0.75 µg/day), 1α hydroxyl calcidiol (ALF; 1 µg/day), plain vitamin D3 (800 IU/day), and control. Before and after the 4-week treatment, intestinal FCA was estimated by using a double isotope method, and serum concentrations of calcium-regulating hormones and a bone turnover marker were measured. RESULTS: The baseline FCA value of the participants was 21.5 ± 7.9% (mean ± SD) and was significantly correlated with serum 1,25(OH)2D (calcitriol) concentration. After the treatment, the FCA significantly increased by 59.5% (95% CI, 41.6 to 77.4%) in the ELD group and by 45.9% (27.9 to 63.8%) in the ALF group, whereas no significant change in the plain vitamin D3 group was found. Unlike the baseline FCA, post-treatment FCA exhibited no significant correlation with serum calcitriol concentration. Parathyroid hormone levels were suppressed by ALF and plain vitamin D3 but were sustained in the ELD and control groups. Serum calcitriol tended to be suppressed by ELD, whereas plain vitamin D3 treatment increased both serum 25(OH)D and calcitriol concentrations. CONCLUSION: These findings suggest that oral administration of vitamin D3 analogues (ALF and ELD) stimulates FCA but plain vitamin D3 does not. Those effects of vitamin D3 compounds on FCA were independent of serum calcitriol concentration, suggesting that ALF and ELD may directly stimulate intestinal vitamin D receptors.

Selectivity of plasma membrane calcium ATPase (PMCA)-mediated extrusion of toxic divalent cations in vitro and in cultured cells.

In the recent years, the toxicity of certain divalent cations has been associated with the alteration of intracellular Ca2+ homeostasis. Among other mechanisms, these cations may affect the functionality of certain Ca2+-binding proteins and/or Ca2+ pumps. The plasma membrane calcium pump (PMCA) maintains Ca2+ homeostasis in eukaryotic cells by mediating the efflux of this cation in a process coupled to ATP hydrolysis. The aim of this work was to investigate both in vitro and in cultured cells if other divalent cations (Sr2+, Ba2+, Co2+, Cd2+, Pb2+ or Be2+) could be transported by PMCA. Current results indicate that both purified and intact cell PMCA transported Sr2+ with kinetic parameters close to those of Ca2+ transport. The transport of Pb2+ and Co2+ by purified PMCA was, respectively, 50 and 75% lower than that of Ca2+, but only Co2+ was extruded by intact cells and to a very low extent. In contrast, purified PMCA-but not intact cell PMCA-transported Ba2+ at low rates and only when activated by limited proteolysis or by phosphatidylserine addition. Finally, purified PMCA did not transport Cd2+ or Be2+, although minor Be2+ transport was measured in intact cells. Moreover, Cd2+ impaired the transport of Ca2+ through various mechanisms, suggesting that PMCA may be a potential target of Cd2+-mediated toxicity. The differential capacity of PMCA to transport these divalent cations may have a key role in their detoxification, limiting their noxious effects on cell homeostasis.

Effects of low phosphorus supply on the availability of calcium and phosphorus, and musculoskeletal development of growing dogs of two different breeds.

To investigate the impact of a selective reduction in dietary phosphorus (P) supply on healthy growing dogs, a total of 23 Beagles and 30 Foxhound crossbreds (FBI) were used in a feeding trial between 6 and 24 weeks of age. Sixteen Beagles and 19 FBI were fed with selectively reduced P concentrations (low phosphorus, LP). The remaining puppies received a completely balanced control diet (CON). With these diets, the P supply in the Beagles at the age of 12 weeks added up to 2.5 ± 0.6 (LP) and 9.8 ± 1.4 g P/kg DM (CON), and in the FBI 4.3 ± 0.9 (LP) and 13.0 ± 1.6 g P/kg DM (CON). Therefore, the LP Beagles received an average of 33 ± 11% of the recommended daily allowances (RDA) of P, the LP FBI 41 ± 11%. The calcium (Ca) concentration stayed unaltered and led to a Ca/P ratio above the recommended range of 1.3/1 to 2/1. The apparent digestibility (aD) of phosphorus was reduced in the LP Beagle; otherwise, the aD of both minerals was not affected by the P concentration of the diet. The renal excretion of P was reduced to zero in both LP groups while the renal calcium excretion increased significantly. Several of the puppies from both breeds showed impaired appetite, growth, skin and fur quality, and a few also clinically showed relevant signs of a disturbed musculoskeletal system after the LP feeding. A rapid loss of muscle strength and posture within hours led to severe deviation of the limb axis with hyperflexion of the joints but no radiological aberrations or signs of pain. Immediate transition of affected puppies to a balanced diet with sufficient phosphorus resulted in a complete recovery of the puppies in less than one month. The results demonstrate the importance of an adequate P supply on the healthy development of growing dogs.

Use of chicken eggshell to improve dietary calcium intake in rural sub-Saharan Africa.

Undernutrition resulting from inadequate access to high-quality, nutritious food is a widespread issue in sub-Saharan Africa impacting the health and survival of mothers and their children. Inadequate dietary intake leads to a deficiency in nutrients including calcium, required for growth and physiological functioning. This study investigated the potential of increasing dietary calcium intake by the addition of heat-treated ground eggshell to locally prepared food. A mixed methods approach of literature review, Delphi expert survey and focus group discussions with women of childbearing age in rural Tanzania, were used to assess the practicality, safety, and acceptability of consumption of ground eggshell. Chicken eggshell has high calcium content (380 mg of calcium/gram) and bioavailability comparable to calcium carbonate (~39%) with 1 g sufficient to provide one half of a sub-Saharan African adult female's dietary calcium needs. Salmonella was indicated as the most likely threat to human health through eggshell consumption. Experts agreed that eggshells boiled for 10 min when preparing hard-boiled eggs with a further 20 min cooking of crushed eggshell in staple foods would eliminate identified egg-associated pathogens. Five focus groups (n = 46) indicated eggshells were perceived as waste. However, there was an indication of general acceptance of the approach and a willingness to consider the incorporation of ground eggshells into their diets. Development of suitable communication methods are required to convey benefits and safe preparation methods. Ground eggshell could be a highly equitable method of increasing calcium intakes across rural sub-Saharan Africa where calcium intake is low and village poultry ownership common.

Chemical Composition, but Not Specific Surface Area, Affects Calcium Retention of Nanostructured Calcium Compounds in Growing Rats.

Background: Low dietary calcium intake and bioavailability may adversely affect bone health. Reducing the size of calcium compounds increases their specific surface area (SSA, expressed as m2/g) and may increase calcium dissolution and bioavailability.Objective: We investigated the influence of SSA and chemical composition on the bioavailability of calcium and compared in vitro calcium dissolution with in vivo absorption.Methods: Calcium dissolution was measured in 0.1 M phosphoric acid, whereas color and pH changes of foods were assessed as indicators for potential sensory performance. Calcium absorption, retention, and fractional retention were measured over a 5-d balance study in growing Sprague-Dawley male rats after 21 d of feeding. Femoral and vertebral bone mineral density (BMD) and extensive tissue histology were assessed at study end. The influence of SSA on calcium bioavailability was assessed by comparing the groups fed pure calcium carbonate (CaCO3) with increasing SSAs of 3, 36, and 64 m2/g (CaCO3_3, CaCO3_36 and CaCO3_64), whereas chemical composition was assessed by comparing the smallest CaCO3_64, a 50:50 wt:wt percent solution mixture of CaCO3 and hydroxyapatite_94, and pure hydroxyapatite_100.Results: In vivo, fractional calcium retention from hydroxyapatite_100 (mean ± SEM: 54.86% ± 0.95%/5 d) was significantly greater than from CaCO3_64 (49.66% ± 1.15%/5 d) (P = 0.044). Increasing SSA of the pure CaCO3 did not significantly improve calcium retention. Across all 5 groups, there were no significant differences in BMD or tissue calcification by histology. In vitro calcium dissolution did not correlate with SSA or calcium absorption. In selected food matrixes, hydroxyapatite_100 caused less color change and/or smaller pH increase than did the other calcium compounds.Conclusions: Our findings suggest that chemical composition rather than SSA is a predictor of nanostructured calcium bioavailability and that in vitro dissolution of nanostructured calcium does not predict in vivo absorption. Although its phosphorus content may limit use in some populations, nanostructured hydroxyapatite may be a promising calcium compound for food fortification.

Calcium Bioavailability from Mineral Waters with Different Mineralization in Comparison to Milk and a Supplement.

OBJECTIVE: The aim of the present study was to compare the bioavailability of calcium from 3 mineral waters with different concentrations of minerals with that of milk and a calcium supplement. METHODS: A single-center, randomized controlled trial with a crossover design with 21 healthy men and women was conducted at the Institute of Food Science and Human Nutrition, Leibniz University Hannover. The participants consumed the 5 test products providing 300 mg of calcium each on 5 examination days with 1-week wash-out phases in between. Primary outcome variables were the area under the curve of serum calcium levels for 10-hour (AUC0-10h) and 24-hour urinary calcium excretion. RESULTS: In all groups, no significant differences in the AUC0-10h of serum calcium levels as well as in the 24-hour urinary calcium excretion were observed. Likewise, mean changes in serum phosphate and urinary phosphate, as well as serum parathormone, showed no differences between the groups. CONCLUSION: Given an equivalent bioavailability of calcium in all test products, neither a high concentration of SO42- or of HCO3 influenced the bioavailability of calcium. Accordingly, the use of mineral water with high concentrations of calcium constitutes a calorie-free calcium source that can improve calcium supply.

Prebiotics and Bone.

Recent advancements in food science have resulted in the extraction and synthesis of novel dietary fibers or prebiotics. Subsequently, great interest has emerged in developing strategies to improve metabolic conditions like osteoporosis by modulating the intestinal microbiome with fiber. Prebiotics have been shown to increase calcium absorption in the lower gut of both animals and humans as well as improve measures of bone mineral density and strength in rodent models. Fewer data are available in humans, but data from growing children and postmenopausal women suggest that prebiotics have both short- and long-term effects that beneficially affect bone turnover and mineral accretion in the skeleton. Currently, the exact mechanism by which these products elicit their effects on bone is poorly understood, but emerging data suggest that the gut microbiota may be involved in one or more direct and indirect pathways. The most well-accepted mechanism is through microbial fermentation of prebiotics which results in the production of short-chain fatty acids and a concomitant decrease in pH which increases the bioavailability of calcium in the colon. While other mechanisms may be eliciting a prebiotic effect on bone, the current data suggest that novel dietary fibers may be an affordable and effective method of maximizing mineral accretion in growing children and preventing bone loss in later years when osteoporosis is a greater risk. This chapter will discuss the dynamic role of prebiotics in bone health by discussing the current state of the art, addressing gaps in knowledge and their role in public health.

Effect of calcium on fatty acid bioaccessibility during in vitro digestion of Cheddar-type cheeses prepared with different milk fat fractions.

Calcium plays an important role in intestinal lipid digestion by increasing the lipolysis rate, but also limits fatty acid bioaccessibility by producing insoluble Ca soaps with long-chain fatty acids at intestinal pH conditions. The aim of this study was to better understand the effect of Ca on the bioaccessibility of milk fat from Cheddar-type cheeses. Three anhydrous milk fats (AMF) with different fatty acid profiles (olein, stearin, or control AMF) were used to prepare Cheddar-type cheeses, which were then enriched or not with Ca using CaCl2 during the salting step. The cheeses were digested in vitro, and their disintegration and lipolysis rates were monitored during the process. At the end of digestion, lipids were extracted under neutral and acidic pH conditions to compare free fatty acids under intestinal conditions in relation to total fatty acids released during the digestion process. The cheeses prepared with the stearin (the AMF with the highest ratio of long-chain fatty acids) were more resistant to disintegration than the other cheeses, owing to the high melting temperature of that AMF. The Ca-enriched cheeses had faster lipolysis rates than the regular Ca cheeses. Chromatographic analysis of the digestion products showed that Ca interacted with long-chain fatty acids, producing Ca soaps, whereas no interaction with shorter fatty acids was detected. Although higher Ca levels resulted in faster lipolysis rates, driven by the depletion of reaction products as Ca soaps, such insoluble compounds are expected to reduce the bioavailability of fatty acids by hindering their absorption. These effects on lipid digestion and absorption are of interest for the design of food matrices for the controlled release of fat-soluble nutrients or bioactive molecules.

Eggshell fractions containing different particle sized affect mineral absorption but not bone mineral retention in growing rats.

The purpose of this study was to compare the calcium (Ca) bioavailability from eggshell fractions containing different particle size to purified CaCO3 in male growing rats. Mineral absorption, bone mineral concentration, and biomechanical properties were evaluated. Mean Ca absorption of rats fed with eggshell diets amounted to 56.2% of the ingested Ca, which is considered high. However, we observed lower Ca absorption in large-sized particle eggshell fraction (ES L) and small-sized particle eggshell fraction groups but similar Ca absorption in intermediate-sized particle eggshell fraction (ES M) compared with the CaCO3 group. Rats that received ES M and ES L had higher P and Mg absorption than the CaCO3 group. No changes were observed in the bone mineral deposition, weight or mechanical resistance. We conclude that eggshell Ca is well absorbed by the intestine and retained in bones of growing rats, being a low cost alternative to achieve adequate Ca ingestion.

Astrocytes and mitochondria from adrenoleukodystrophy protein (ABCD1)-deficient mice reveal that the adrenoleukodystrophy-associated very long-chain fatty acids target several cellular energy-dependent functions.

X-linked adrenoleukodystrophy (X-ALD) is a severe neurodegenerative disorder resulting from defective ABCD1 transport protein. ABCD1 mediates peroxisomal uptake of free very-long-chain fatty acids (VLCFA) as well as their CoA-esters. Consequently, VLCFA accumulate in patients' plasma and tissues, which is considered as pathogenic X-ALD triggering factor. Clinical symptoms are mostly manifested in neural tissues and adrenal gland. Here, we investigate astrocytes from wild-type control and a genetic X-ALD mouse model (Abcd1-knockout), exposed to supraphysiological VLCFA (C22:0, C24:0 and C26:0) concentrations. They exhibit multiple impairments of energy metabolism. Furthermore, brain mitochondria from Abcd1(-/-) mice and wild-type control respond similarly to VLCFA with increased ROS generation, impaired oxidative ATP synthesis and diminished Ca(2+) uptake capacity, suggesting that a defective ABCD1 exerts no adaptive pressure on mitochondria. In contrast, astrocytes from Abcd1(-/-) mice respond more sensitively to VLCFA than wild-type control astrocytes. Moreover, long-term application of VLCFA induces high ROS generation, and strong in situ depolarization of mitochondria, and, in Abcd1(-/-) astrocytes, severely diminishes the capability to revert oxidized pyridine nucleotides to NAD(P)H. In addition, observed differences in responses of mitochondria and astrocytes to the hydrocarbon chain length of VLCFA suggest that detrimental VLCFA activities in astrocytes involve defective cellular functions other than mitochondria. In summary, we clearly demonstrate that VLCFA increase the vulnerability of Abcd1(-/-) astrocytes.

The Effect Of NO Donor on Calcium Uptake and Reactive Nitrogen Species Production in Mitochondria.

BACKGROUND/AIMS: NO and reactive nitrogen species (RNS) are thought to be physiologically important effectors of mitochondrial calcium transport, but this issue was not studied in a living organism. According to literature, the modulation of Ca2+ uptake could influence RNS production via the action on mitochondrial NO synthase (mtNOS). The aim of this work was to study the effect of in vivo administration of NO donor nitroglycerine (NG) on matrix Ca2+ accumulation, RNS production and mtNOS activity. METHODS: Ca2+ uptake was studied spectrophotometrically with arsenazo-III. The amounts of stable RNS (nitrite, nitrate and nitrosothiols) and L-citrulline, the product of enzymatic NOS activity, were determined analytically. RESULTS: NG administration resulted in dose-dependent short-term increase in Ca2+-uptake accompanied by essential rise in L-citrulline and RNS content in mitochondria. In parallel, dose-dependent elevation of hydroperoxide production was detected. Ca2+-uniporter activity was not affected, but mitochondrial permeability transition pore (MPTP) was effectively blocked by NO. CONCLUSION: Our results indicate that MPTP blockage by NO was the primary cause for the increase in calcium uptake which eventually resulted in the activation of mtNOS and RNS production. Improved Ca2+ accumulation in mitochondria, together with MPTP blockage, may contribute to well-known cardioprotective effects of pharmacological donors of nitric oxide.

Extracellular calcium influx promotes antibacterial autophagy in Escherichia coli infected murine macrophages via CaMKKß dependent activation of ERK1/2, AMPK and FoxO1.

Autophagy induction has been found as an alternative mechanism for ultimate elimination of invaded bacteria in innate immune cells. However, underlying mechanisms for the regulation of antibacterial autophagy require further elucidation. The present study mainly explores calcium dependent regulation of autophagy and its contribution to bactericidal activity in Escherichia coli (E. coli) infected murine macrophages. In this study, E. coli was shown to increase cellular calcium levels by triggering extracellular calcium influx in murine bone marrow derived macrophages. The elevated calcium was required for autophagy and bactericidal activity against E. coli, as extracellular calcium depletion or inhibition of calcium influx suppressed E. coli induced Beclin1 and LC3B expression, dampened LC3B puncta or LC3I to LC3II conversion and impaired intracellular E. coli degradation. Then CaMKKß was identified as activated by E. coli induced calcium influx and chemical inhibition or RNAi knockdown of CaMKKß abolished calcium mediated antibacterial autophagy. CaMKKß was demonstrated to activate signaling pathways involving ERK, AMPK and FoxO1 and RNAi knockdown of these molecules also dampened the antibacterial autophagy against E. coli. In summary, we demonstrate a new mechanism of calcium dependent antibacterial strategy in E. coli infected macrophages, which requires autophagy enhancement mediated by activation of CaMKKß, ERK, AMPK and FoxO1.