Abstract  The Na(+)/H(+) exchanger has been the only unequivocally demonstrated H(+)-transport mechanism in the synaptosomal preparation. We had previously suggested that a Cl(-)-H(+) symporter (in its acidifying mode) is involved in cytosolic pH regulation in the synaptosomal preparation. Supporting this suggestion, we now show that: (1) when synaptosomes are transferred from PSS to either gluconate or sulfate solutions, the Fura-2 ratio remains stable instead of increasing as it does in 50 mM K solution. This indicates that these anions do not promote a plasma membrane depolarization. (2) Based in the recovery rate from the cytosolic alkalinization, the anionic selectivity of the Cl(-)-H(+) symporter is NO(3)(-) > Br(-) > Cl(-) > I(-) = isethionate = sulfate = methanesulfonate = gluconate. (3) PCMB 10 muM inhibits the gluconate-dependent alkalinization by 30 +/- 6%. (4) Neither Niflumic acid, 9AC, Bumetanide nor CCCP inhibits the recovery from the cytosolic alkalinization.

Abstract  1. Although calcium gluconate (CG) is recommended in the treatment of hydrofluoric acid (HF) eye burn its efficacy seems to be controversial, and controlled human or animal studies are limited. The study's objective is to compare the efficacy of 1% CG and normal saline irrigation for the treatment of HF eye injury in animals. 2. 0.05 ml 2% HF was instilled to anesthetized rabbit's eyes. One minute later, four treatment groups were studies: (1) irrigation with normal saline followed by topical antibiotics, corticosteroids and cycloplegics for 48 h (n = 10); (2) irrigation with 1% CG followed by the same topical treatment (n = 9); (3) as group 1 and 1% CG drops over 48 h (n = 10); (4) as group 3, and injection of 1% CG subconjunctivally after irrigation (n = 9). 3. Corneal erosion area, corneal haziness, conjunctival status, vascularization (pannus) and acidity were assessed before injury, immediately after initial treatment and 1, 2, 7 and 14 days thereafter by slit lamp aided by fluorescein staining. 4. Conjunctival pH dropped from 6.0-6.5 to 2.5-3 after injury and increased to 6-6.5 after irrigation. Corneal erosion: smaller in groups 2, 3, significantly so at 2 days, but not different at 14 days. Corneal haziness: more severe in group 4, at 14 days, insignificant. Conjunctival damage: significantly worse in group 4 at 2, 7 and 14 days. Pannus appeared in 2-4 eyes in each group. 5. It seems that for HF injury 1% CG did not have any significant advantage over saline irrigation and topical treatment only. It might have some initial and temporary effect on healing process especially that involving erosion. Given subconjunctivally, 1% CG may be toxic and worsens clinical outcome.

Abstract  The regulation of PTH secretion by calcium is altered in patients with primary hyperparathyroidism. A similar disturbance may occur in secondary hyperparathyroidism, but direct in vivo comparisons of PTH secretion in normal subjects and those with secondary hyperparathyroidism have not been made. Thus, 13 patients with end-stage renal failure and secondary hyperparathyroidism and 20 healthy volunteers underwent dynamic tests of PTH secretion. Changes in ionized calcium were induced by 2-h iv infusions of calcium gluconate or sodium citrate on consecutive days, and the sigmoidal relationship between serum ionized calcium and PTH levels was examined. During sodium citrate infusions, serum ionized calcium levels decreased by 0.21 +/- 0.04 and 0.20 +/- 0.05 mmol/L, respectively (mean +/- SD), in normal volunteers and dialyzed patients (P = NS). Serum PTH levels rose from 27 +/- 7 to 107 +/- 33 pg/mL in controls and from 480 +/- 238 to 859 +/- 412 pg/mL in dialyzed subjects; thus, maximum PTH levels were 396% of preinfusion values in normal subjects, but only 79% greater than baseline values in dialyzed patients (P < 0.001). During the first 30 min of calcium infusions, the increase in serum ionized calcium did not differ between groups, but PTH levels fell more rapidly in normal volunteers; values were 24% of preinfusion levels in controls, but only 56% of the baseline in dialyzed patients (P < 0.01) after 30 min. Minimum PTH levels were attained after 50 min of calcium infusion in normal volunteers and after 70 min in dialyzed patients. The derived values for set-point were 1.21 +/- 0.04 and 1.24 +/- 0.06 mmol/L, respectively, in control and dialyzed subjects (P = NS). These results do not support the contention that the set-point for calcium-regulated PTH secretion is greater than normal in patients with secondary hyperparathyroidism due to end-stage renal disease.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. A multinational interlaboratory study to investigate the bovine corneal opacity and permeability (BCOP) assay is presented. The aim of this work was to determine the capability and possible limitations of this method to predict ocular irritancy of a large set of chemicals. The assays were carried out in 12 European laboratories with different types of activity. In each of these laboratories 52 substances, with a wide range of structure, physical form and irritant properties, were tested and in vitro scores were compared with those obtained from concurrent rabbit eye (Draize) tests. The technique was easily learned by workers in the participating laboratories, as shown by the fact that there were consistent responses between treated corneas within an individual laboratory. Interlaboratory variability was also very good. It was found that a given laboratory had a 96% chance of classifying irritants or non-irritants similarly to the other laboratories. In addition, it was

Abstract  Effects of several Cl(-) channel blockers on ionic currents in mouse embryos were studied using whole-cell patch-clamp and microelectrode methods. Microelectrode measurements showed that the resting membrane potential of early embryonic cells (1-cell stage) was -23 mV and that reduction of extracellular Cl(-) concentration depolarized the membrane, suggesting that Cl(-) conductance is a major contributor for establishing the resting membrane potential. Membrane currents recorded by whole-cell voltage clamp showed outward rectification and confirmed that a major component of these embryonic currents are carried by Cl(-) ions. A Cl(-) channel blocker, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), suppressed the outward rectifier current in a voltage- and concentration-dependent manner. Other Cl(-) channel blockers (5-nitro-2-[3-phenylpropyl-amino] benzoic acid and 2-[3-(trifluoromethyl)-anilino] nicotinic acid [niflumic acid]) similarly inhibited this current. Simultaneous application of niflumic acid with DIDS further suppressed the outward rectifier current. Under high osmotic condition, niflumic acid, but not DIDS, inhibited the Cl(-)current, suggesting the presence of two types of Cl(-) channels: a DIDS-sensitive (swelling-activated) channel, and a DIDS-insensitive (niflumic acid-sensitive) Cl(-) channel. Anion permeability of the DIDS-insensitive Cl(-) current differed from that of the compound Cl(-) current: Rank order of anion permeability of the DIDS-sensitive Cl(-) channels was I(-) = Br(-) > Cl(-) > gluconate(-), whereas that of the DIDS-insensitive Cl(-) channel was I(-) = Br(-) > Cl(-) > gluconate(-). These results indicate that early mouse embryos have a Cl(-) channel that is highly permeable to amino acids, which may regulate intracellular amino acid concentration.

Abstract  The pharmacokinetics of fluoride and calcium were studied after administration of a combined fluoride and calcium preparation (Tridin) (1, 2 and 3 tablets) in 9 healthy male volunteers, using a cross-over study design. The total estimation of the pharmacokinetic data was performed by a simultaneous curve fitting to all single values, using a direct search procedure based on an open two-compartment model and three-compartment model, respectively. Maximum plasma concentrations and areas under the curve are proportional to the dose administered. Inter-subject variations are comparatively small, computerized multiple dose simulation for 3 days does not show any cumulation. The data fit the two-compartment model and the three-compartment model as well. The behaviour of the calcium concentrations reflects the immediate response of calcium homeostasis: plasma calcium concentrations are not affected.

Abstract  Mutagenic test results are reported in microbial and mammalian cell systems.

Abstract  IPA COPYRIGHT: ASHP Potassium chloride, as a sugar coated tablet embedded in a wax matrix (Slow-K) and potassium gluconate solution (Kaon), were compared in 20 outpatients suffering from hypertension and receiving potassium wasting diuretics, capable of producing hypokalemia. The patients were randomly divided into 2 groups of 10 each. One group received the solution for 4 weeks (40 meq potassium/day) and was then switched to the tablet (48 meq/day) for another 4 weeks. The second group began treatment with the tablet, crossing over to the solution after 4 weeks. The patients completed a self rating questionnaire on preference and GI side effects after each 4 week period. Both medications appeared equally effective in maintaining serum levels of potassium and chloride. GI side effects were not severe with either preparation. No gross or occult blood was detected in the stools for any patient. Patient preferences favored the tablet. Ninety-five per cent of the subjects found the tablets more acceptable than the liquid, and 90% found them more convenient. Based upon these findings, the tablet appears to possess decided clinical advantage over a solution with respect to patient compliance and acceptance.

Abstract  Individual outer hair cells isolated from guinea pig cochleae were observed in vitro during the application of solutions that are known to cause hair cells to shorten. Solutions containing high potassium, which depolarizes cells, were applied in the form of potassium gluconate. The initial response was a shortening, followed by an elongation, after which the hair cells nearly resumed their original length. Solutions containing the presumed efferent neurotransmitter acetylcholine also caused an initial shortening, occasionally followed by an elongation, where a cell either returned to normal or exceeded its original length. Solutions containing cationized ferritin caused some cells to shorten and caused others to lengthen. The results indicate that the hair cell response to a chemical stimulus can be bidirectional. Moreover, the initial response of an individual cell may depend not only on the stimulus but also on the physiological state of the hair cell or the original location of the hair cell along the length of the sensory epithelium when it was in the cochlea.

Abstract  We evaluated the impact of three calcium salts on the calcium-parathyroid axis in healthy elderly volunteers. Fasting subjects were administered a standardized 1-g calcium load on three occasions, using calcium carbonate, lactate, and gluconate in random sequence with 8 oz milk or orange juice as carrier. Blood and urine were collected at baseline and for 6 h following the calcium load. Each salt rapidly increased the serum-calcium concentration and urinary-calcium excretion. Response duration was shorter with gluconate than with the other salts, but peak responses were similar for all preparations. Urinary-calcium excretion was slightly lower when orange juice replaced milk, but calcemic responses were not different. Changes in immunoreactive-parathyroid hormone and renal-phosphorus handling did not differ among calcium salts. Except for a shorter duration of effect with gluconate, all three calcium salts provided similar short-term suppression of the parathyroid axis.

Abstract  Calcium gluconate (22.4 g/day; 2 g/day as Ca) was administered orally for 8 weeks to eight hospitalized elderly patients with essential hypertension in order to confirm the hypotensive effect of oral calcium supplementation and to clarify its hypotensive mechanism by analyzing changes in hormonal factors. After 2 weeks of calcium supplementation, both systolic and diastolic pressures decreased significantly and remained decreased for the duration of the study. An elevation of plasma PGE2 correlated with blood pressure reduction was observed at 2 weeks. Plasma norepinephrine decreased significantly from 4 weeks. Plasma parathyroid hormone decreased significantly from 4 weeks, and 1,25-dihydroxyvitamin D (1,25-[OH]2D) decreased significantly at 8 weeks. The reduction of plasma 1,25-(OH)2D correlated with blood pressure decrease at 8 weeks. The present study indicates that the mechanism of its hypotensive effect is multifactorial and may be different during different phases of calcium supplementation. The suppression of plasma 1,25-(OH)2D following reduction of parathyroid hormone may be involved in the hypotensive effect in the chronic phase of calcium supplementation. Enhancement of PGE2 production in the early phase and suppression of sympathetic nervous activity in the chronic phase may also be factors in blood pressure reduction.

Abstract  Using anti-human calcitonin serum and a protein A - gold technique, calcitonin was localized at the ultrastructural level in control and calcium gluconate-stimulated thyroid C cells of the rat. In control rats calcitonin was detected within a majority of the secretory granules while in experimental animals it was demonstrated also within prosecretory granules present in Golgi apparatus.

Abstract  Cardiomyocytes (CMs) undergo a rapid transition from hyperplastic to hypertrophic growth soon after birth, which is a major challenge to the development of engineered cardiac tissue for pediatric patients. Resting membrane potential (Vmem) has been shown to play an important role in cell differentiation and proliferation during development. We hypothesized that depolarization of neonatal CMs would stimulate or maintain CM proliferation in vitro. To test our hypothesis, we isolated postnatal day 3 neonatal rat CMs and subjected them to sustained depolarization via the addition of potassium gluconate or Ouabain to the culture medium. Cell density and CM percentage measurements demonstrated an increase in mitotic CMs along with a ~2 fold increase in CM numbers with depolarization. In addition, depolarization led to an increase in cells in G2 and S phase, indicating increased proliferation, as measured by flow cytometry. Surprisingly depolarization of Vmem with either treatment led to inhibition of proliferation in cardiac fibroblasts. This effect is abrogated when the study was carried out on postnatal day 7 neonatal CMs, which are less proliferative, indicating that the likely mechanism of depolarization is the maintenance of the proliferating CM population. In summary, our findings suggest that depolarization maintains postnatal CM proliferation and may be a novel approach to encourage growth of engineered tissue and cardiac regeneration in pediatric patients.

Abstract  A 6-month-old, female border collie was referred for evaluation of hypocalcemia, hyperphosphatemia, fever, and painful ventral abdominal skin. She had recently been treated intravenously and subcutaneously (SC) with a diluted 10% calcium gluconate solution. The medical evaluation supported the diagnosis of primary hypoparathyroidism, but the subsequent hospital course was complicated by severe calcinosis cutis, which caused extensive skin necrosis and marked debilitation. This patient illustrates that administration of a calcium gluconate solution SC can be associated with extensive morbidity when administered to hyperphosphatemic patients.

Abstract  BACKGROUND: Stanniocalcin (STC) is a polypeptide hormone first discovered in fish and more recently in mammals. In mammals, STC is produced in many tissues and does not normally circulate in the blood. In kidney and gut, STC regulates phosphate fluxes across the transporting epithelia, whereas in brain it protects neurons against cerebral ischemia and promotes neuronal cell differentiation. The gene is highly expressed in ovary and dramatically up-regulated during pregnancy and nursing. Gene expression also is high during mammalian embryogenesis, particularly in kidney where the hormone signals between epithelial and mesenchymal cells during nephrogenesis.

METHODS: This study examined the patterns of STC gene expression and protein distribution in the mouse kidney over the course of post-natal development. Further, because STC is a regulator of renal phosphate transport, we also examined the effects of changing levels of dietary calcium and phosphate on renal levels of STC gene expression in adult rats.

RESULTS: STC mRNA levels in the neonate kidney were found to be tenfold higher than adults. Isotopic in situ hybridization of neonate kidneys revealed that most, if not all, STC mRNA was confined to collecting duct (CD) cells, as is the case in adults. STC protein on the other hand was found in proximal tubule, thick ascending limb and distal tubules in addition to CD cells. This suggests that, as in adults, the more proximal nephron segments in neonates are targeted by CD-derived STC and sequester large amounts of hormone. The addition of 1% calcium gluconate to the drinking water significantly reduced STC mRNA levels in inner medullary CD cells of both males and females, but not those in the cortex and outer medulla. Placing animals on low phosphate diets also reduced STC mRNA levels, but uniquely in outer medullary and cortical CD cells, whereas a high phosphate diet increased transcript levels in the same regions.

CONCLUSIONS: These findings suggest that STC may be of unique importance to neonates. They also suggest that changes in dietary calcium and phosphate can alter renal levels of STC gene expression, but that these effects vary between the early and late segments of the collecting duct.

Abstract  The effects of serum and brain calcium concentration on rat behavior were tested by maintaining animals on either distilled water (N = 60) or water containing 1% calcium gluconate (N = 60) for 3 days. Animals that were maintained on high calcium drinking water presented increased serum calcium levels (control = 10.12 +/- 0.46 vs calcium treated = 11.62 +/- 0.51 mug/dl). Increase of brain calcium levels was not statistically significant. In the behavioral experiments each rat was used for only one test. Rats that were maintained on high calcium drinking water showed increased open-field behavior of ambulation (20.68%) and rearing (64.57%). On the hole-board, calcium-supplemented animals showed increased head-dip (67%) and head-dipping (126%), suggesting increased ambulatory and exploratory behavior. The time of social interaction was normal in animals maintained on drinking water containing added calcium. Rats supplemented with calcium and submitted to elevated plus-maze tests showed a normal status of anxiety and elevated locomotor activity. We conclude that elevated levels of calcium enhance motor and exploratory behavior of rats without inducing other behavioral alterations. These data suggest the need for a more detailed analysis of several current proposals for the use of calcium therapy in humans, for example in altered blood pressure states, bone mineral metabolism disorders in the elderly, hypocalcemic states, and athletic activities.

Abstract  Changes in the extracellular calcium concentration have important effects on hormone secretion. In vitro, kidney juxtaglomerular cells have been shown to secrete renin in an inverse relationship to the extracellular calcium concentration. The effect of physiologic changes in calcium on renin secretion in humans is less clear. We therefore investigated the effects of physiologic changes in extracellular calcium levels on renin and aldosterone secretion in 7 healthy men. Serum ionized calcium, ACTH, plasma renin activity (PRA), and aldosterone levels were serially measured during 90-min infusions of dextrose, disodium edetate (EDTA) and calcium gluconate, and the latter two infusions were repeated with dexamethasone pre-treatment. ACTH levels decreased during the 5% dextrose in water and the EDTA infusions but increased during the calcium infusion. Similarly, PRA and aldosterone levels fell during the D5W and EDTA infusions but this decrease was absent with increments in calcium levels. Dexamethasone administration suppressed ACTH and the aldosterone response to calcium but did not affect the PRA response to the calcium infusion. Our data indicate that increases in calcium within the physiological range blunt the diurnal decline in both PRA and aldosterone. This appears to be a direct effect of calcium on PRA but mediated through ACTH in the case of aldosterone.

Abstract  The present study was conducted to follow up on apparent differences in growth, relative organ sizes, cellular stress and immune function in Atlantic salmon fed feed containing GM Bacillus thuringiensis maize compared with feed containing the non-modified parental maize line. Gene expression profiling on the distal intestinal segment and liver was performed by microarray, and selected genes were followed up by quantitative PCR (qPCR). In the liver, qPCR revealed some differentially regulated genes, including up-regulation of gelsolin precursor, down-regulation of ferritin heavy subunit and a tendency towards down-regulation of metallothionein (MT)-B. This, combined with the up-regulation of anti-apoptotic protein NR13 and similar tendencies for ferritin heavy chain and MT-A and -B in the distal intestine, suggests changes in cellular stress/antioxidant status. This corresponds well with and strengthens previous findings in these fish. To exclude possible confounding factors, the maize ingredients were analysed for mycotoxins and metabolites. The GM maize contained 90 μg/kg of deoxynivalenol (DON), while the non-GM maize was below the detection limit. Differences were also observed in the metabolite profiles of the two maize varieties, some of which seemed connected to the mycotoxin level. The effects on salmon observed in the present and previous studies correspond relatively well with the effects of DON as reported in the literature for other production animals, but knowledge regarding effects and harmful dose levels in fish is scarce. Thus, it is difficult to conclude whether the observed effects are caused by the DON level or by some other aspect of the GM maize ingredient.