Early vs late initiation of sodium glycerophosphate: Impact on hypophosphatemia in preterm infants <32 weeks.

BACKGROUND & AIMS: Early electrolyte and mineral imbalances have emerged as a conspicuous problem in very preterm babies since the revision of nutrition guidelines and the eventual implementation of early aggressive parenteral nutrition (PN). We opted to carry out a study with the introduction of phosphorus as sodium glycerophosphate in PN from the first day onward to reveal the impact on serum phosphorus and calcium levels following the surge in the incidence of hypercalcemia and hypophosphatemia. METHODS: In this single-center, prospective, observational cohort study, inborn babies <32 gestational weeks and <1500 g between August 2017 and July 2018 were enrolled consecutively. Infants born in the first 6-month of this period were initiated PN (Early phosphorus group) containing phosphorus (1 mmol P as sodium glycerophosphate/100 ml PN) immediately after birth, and in the latter six-months, mineral-free standard PN (Control group) was commenced up until 48 h of life. Parenteral nutritional prescriptions of both groups were similar in terms of macro and micronutrient intakes except for early phosphorus, calcium, and sodium. Serum mineral and electrolyte levels were measured on Days 1-3-7 and compared between the groups. The primary outcome was the presence of hypophosphatemia in the first week of life. The secondary outcome was hypercalcemia, preterm morbidity, and mortality. RESULTS: A total of 261 infants were included in this study. There were 130 babies in Early phosphorus group and 131 in control group. Gestational ages (28.79 ± 2.1 vs 28.46 ± 2.2 weeks, respectively) and birth weights (1138 ± 273 vs 1090 ± 274 g, respectively) were similar in the groups. Mean serum phosphorus levels were higher on all days in Early phosphorus group (p < 0.001). Early phosphorus group had a lower incidence of hypophosphatemia on days 1-3 and 7 (p < 0.001). The percentage of hypercalcemic infants was significantly lower in Early phosphorus group on day 3 (p < 0.001). No difference was noted in terms of hypernatremia in the groups. CONCLUSIONS: Adding phosphorus to PN in the first hours of life reduced the frequency of hypophosphatemia and hypercalcemia without any surge in hypernatremia or morbidity. Nutrition guidelines need to be revised accordingly in terms of early mineral/electrolyte supplementation.

Growth and Bone Mineralization of Very Preterm Infants at Term Corrected Age in Relation to Different Nutritional Intakes in the Early Postnatal Period.

Preterm infants often have a reduced bone mineral content (BMC) with increased risk of metabolic bone disease. After birth it is difficult to supply calcium (Ca) and phosphorus (P) comparable to the high fetal accretion rate. It is not known whether high supplementation of minerals in the early postnatal period improves growth and bone mineralization. The aim of this study was to evaluate growth and bone mineralization at term corrected age (TCA) in very and extremely preterm infants who received different enteral Ca and P intakes during the first 10 days of life. Infants (n = 109) with birth weights below 1500 g were randomly assigned to one of three groups that differed in the nutritional protocols delivered until day 10: Group A, mother's own milk (MOM) and donor milk (unfortified); Group B, MOM (unfortified) and preterm formula; Group C, MOM (start fortification >50 mL/day) and preterm formula. Due to the earlier commencement of fortification, Group C received higher intakes of calcium and phosphorus and protein (p < 0.001) until day 10. At TCA weight, length, BMC and bone mineral density (BMD), measured by dual-X-ray absorptiometry, were not different between the groups. Nutritional intake of P was positively associated with length (ß; (95% confidence interval (CI): 0.20 (0.001; 0.393); p-value = 0.048), whereas Ca intake was negatively associated with BMC (-1.94 (-2.78; -1.09); p-value < 0.001). A small interaction between Ca and P intake was only found for BMD (0.003 (0.00002; 0.00006); p-value = 0.036). The volume of human milk per kg provided during the first 10 days was positively associated with BMC (ß; (95% CI): 0.013 (0.002; 0.023); p < 0.017). Higher intakes of Ca and P during the first 10 days, as provided in this study, did not improve bone mineralization at term corrected age.

Can babies oral wipes with fluoride and/or calcium glycerophosphate prevent cariogenic demineralization? An in-vitro study.

BACKGROUND: The difficulties in reaching a good level of oral hygiene in young babies can be partly overcome with the use of baby oral wipes, which have been shown to effectively remove plaque from deciduous teeth. The presence of fluoride and calcium in these wipes could also prevent further demineralization of the teeth, as well as promote remineralization. The aim of this study is, therefore, was to analyze the preventive effect of OW containing F and CaGP on cariogenic demineralization in vitro. METHODS: For this, seventy enamel samples were treated with OW soaked in solutions containing different F concentrations (250 ppm; 500 ppm and 1500 ppm) with or not with 0.13% CaGP and distilled water for the control group. The samples were submitted to an 8-day cariogenic pH cycling. The experimental solutions were applied twice per cycle, by immersing a dry inert oral tissue into 4 mL of the solution and rubbing it over the enamel surface. Enamel microhardness was measured initially and after the experimental cycles. Environmental scanning electron microscope was taken to visualize and quantify elements on the enamel surface. RESULTS: No significant difference was observed (P=0.694), but when the groups containing CaGP were compared to the negative control solution, a significant difference was found. CONCLUSIONS: The presence of 0.13% CaGP and fluoride in concentrations greater than 500 ppm were able to provide protection of dental enamel against demineralization.

Does Adding Intravenous Phosphorus to Parenteral Nutrition Has Any Effects on Calcium and Phosphorus Metabolism and Bone Mineral Content in Preterm Neonates?

The use of parenteral nutritional supplementation of phosphorus may lead to exhibit higher plasma phosphate concentrations and less radiological features in premature neonates susceptible to osteopenia. The present study aimed to assess the beneficial effects of adding intravenous phosphorus to total parenteral nutrition (TPN) on calcium and phosphorus metabolism in preterm neonates by measuring bone mineral content. This open-labeled randomized clinical trial was conducted on premature neonates who were hospitalized at NICU. The neonates were randomly assigned to two groups received TPN with intravenous sodium glycerophosphate or Glycophos (1.5 mmol/kg/day) or TPN without sodium glycerophosphate. At the end of the four weeks of treatment, the presence of osteopenia was examined using DEXA Scan. After completing treatment protocols, the group received TPN with intravenous Glycophos had significantly lower serum alkaline phosphatase (360±60 versus 762±71, P<0.001), as well as higher serum calcium to creatinine ratio (1.6±0.3 versus 0.44±0.13, P<0.001) compared to the control group received TPN without Glycophos. Those who received TPN with intravenous Glycophos experienced more increase in bone mineral density than those in control group (0.13±0.01 versus 0.10±0.02, P<0.001). There was no significant difference in serum calcium and serum vitamin D between the case and control groups. Adding intravenous sodium glycerophosphate to TPN in premature neonates can compensate the lack of bone mineral content and help to prevent osteopenia.

Effects of Gingko biloba extract (EGb 761) on vascular smooth muscle cell calcification induced by ß-glycerophosphate.

OBJECTIVE: To investigate the effects of Gingko biloba extract (EGb 761) on calcification induced by ß-glycerophosphate in rat aortic vascular smooth muscle cells. METHODS: Rat aortic vascular smooth muscle cells were cultured with various concentrations of EGb 761 and ß-glycerophosphate for 7 days. Calcium content in the cells, alkaline phosphatase activity, cell protein content, NF-κB activation, and reactive oxygen species production were assayed, respectively. RESULTS: The calcium depositions of vascular smooth muscle cells of the ß-glycerophosphate group were significantly higher than those of the control group (p < 0.01), and were inhibited by EGb 761 in a concentration-dependent manner (p < 0.05). Data showed ß-glycerophosphate induced the enhanced expression of alkaline phosphatase, up-regulated the NF-κB activity and increased reactive oxygen species production of vascular smooth muscle cells while these decreased when administrated with EGb 761(p < 0.05). CONCLUSIONS: EGb 761 significantly reduced deposition of calcium induced by ß-glycerophosphate in rat aortic vascular smooth muscle cells. It not only reduced the deposition of calcium, but also inhibited osteogenic transdifferentiation, which may be associated with decreasing expression of alkaline phosphatase, down-regulating the NF-κB activity, and reducing reactive oxygen species production of vascular smooth muscle cells, and may have the potential to serve as a role for vascular calcification in clinical situations.

In situ evaluation of low-fluoride toothpastes associated to calcium glycerophosphate on enamel remineralization.

OBJECTIVES: This study aimed to evaluate the effect of low-fluoride toothpastes with calcium glycerophosphate (CaGP) on enamel remineralization in situ. METHODS: Volunteers (n=10) wore palatal devices holding four bovine enamel blocks. The treatments involved 5 experimental phases of 3 days each according to the following toothpastes: placebo, 500 ppm F (500 NaF), 500 ppm F with 0.25% CaGP (500 NaF CaGP), 500 ppm F with 0.25% CaGP (500 MFP CaGP) and 1100 ppm F (1100; positive control). After this experimental period, the fluoride, calcium, and phosphorus ion concentrations from enamel were determined. Surface and cross-sectional hardness were also performed. Data were analysed by 1-way ANOVA, Student-Newman-Keuls' test and by Pearson's correlation. RESULTS: The addition of 0.25% CaGP improved the remineralization potential of low-fluoride toothpastes and the NaF as source of fluoride yielded the best results (p<0.001) as evidenced by the hardness analysis. The 1100 ppm F toothpaste provided higher presence of fluoride in the enamel after remineralization (p<0.001). The addition of CaGP to the NaF and MFP toothpastes led to similar calcium concentration in the enamel as the observed with the positive control (p=0.054). CONCLUSIONS: Toothpastes with 500 ppm F (NaF or MFP) and CaGP showed similar remineralization potential than 1100 ppm F toothpaste. CLINICAL SIGNIFICANCE: Toothpastes containing 500 ppm F associated to CaGP, with both fluoride source (NaF or MFP), showed a potential of remineralization similar to commercial toothpaste. Although there is a need for confirmation in the clinical setting, these results point to an alternative for improving the risk-benefit relationship between fluorosis and dental caries in small children.

Effect of low-fluoride dentifrices supplemented with calcium glycerophosphate on enamel demineralization in situ.

PURPOSE: To evaluate whether a low-fluoride dentifrice with calcium glycerophosphate (CaGP) reduced the demineralization process in situ. METHODS: A cross-over design with four treatment phases of 7 days each was used. Ten volunteers wore palatal devices containing four blocks of bovine dental enamel. The enamel was treated (ex-vivo) with a placebo, 500 microg-F/g (500), 500 microg-F/g with 0.25%CaGP (500 CaGP), and 1,100 microg-F/g (1,100) dentifrices (twice a day/1 minute) under cariogenic challenge from sucrose solution. To evaluate mineral loss, surface and cross-sectional hardness were performed. The fluoride, calcium, and phosphorus ion concentrations from enamel and dental plaque were determined. The insoluble extracellular polysaccharide (EPS) concentrations were also analyzed. The data were submitted to ANOVA (1-way) followed by the Student-Newman-Keuls test (P < 0.05). RESULTS: The mineral loss and EPS concentration were lowest in the 500 CaGP and 1,100 dentifrice groups. The use of the 500 CaGP and 1,100 dentifrices resulted in similar fluoride, calcium, and phosphorus concentrations in the enamel and in dental plaque (P > 0.05). The ionic activities of calcium phosphate phases for the 500 CaGP and 1,100 dentifrices were similar (P > or = 0.492). The low-fluoride dentifrice with 0.25%CaGP demonstrated efficacy similar to that of the positive control (1,100 dentifrice) with respect to in situ demineralization.

Novel synthetic (poly)glycerolphosphate-based antistaphylococcal conjugate vaccine.

Staphylococcal infections are a major source of global morbidity and mortality. Currently there exists no antistaphylococcal vaccine in clinical use. Previous animal studies suggested a possible role for purified lipoteichoic acid as a vaccine target for eliciting protective IgG to several Gram-positive pathogens. Since the highly conserved (poly)glycerolphosphate backbone of lipoteichoic acid is a major antigenic target of the humoral immune system during staphylococcal infections, we developed a synthetic method for producing glycerol phosphoramidites to create a covalent 10-mer of (poly)glycerolphosphate for potential use in a conjugate vaccine. We initially demonstrated that intact Staphylococcus aureus elicits murine CD4(+) T cell-dependent (poly)glycerolphosphate-specific IgM and IgG responses in vivo. Naive mice immunized with a covalent conjugate of (poly)glycerolphosphate and tetanus toxoid in alum plus CpG-oligodeoxynucleotides produced high secondary titers of serum (poly)glycerolphosphate-specific IgG. Sera from immunized mice enhanced opsonophagocytic killing of live Staphylococcus aureus in vitro. Mice actively immunized with the (poly)glycerolphosphate conjugate vaccine showed rapid clearance of staphylococcal bacteremia in vivo relative to mice similarly immunized with an irrelevant conjugate vaccine. In contrast to purified, natural lipoteichoic acid, the (poly)glycerolphosphate conjugate vaccine itself exhibited no detectable inflammatory activity. These data suggest that a synthetic (poly)glycerolphosphate-based conjugate vaccine will contribute to active protection against extracellular Gram-positive pathogens expressing this highly conserved backbone structure in their membrane-associated lipoteichoic acid.

Injectable thermosensitive hydrogel based on chitosan and quaternized chitosan and the biomedical properties.

A novel injectable thermosensitive hydrogel (CS-HTCC/alpha beta-GP) was successfully designed and prepared using chitosan (CS), quaternized chitosan (HTCC) and alpha,beta-glycerophosphate (alpha,beta-GP) without any additional chemical stimulus. The gelation point of CS-HTCC/alpha beta-GP can be set at a temperature close to normal body temperature or other temperature above 25 degrees C. The transition process can be controlled by adjusting the weight ratio of CS to HTCC, or different final concentration of alpha,beta-GP. The optimum formulation is (CS + HTCC) (2% w/v), CS/HTCC (5/1 w/w) and alpha,beta-GP 8.33% or 9.09% (w/v), where the sol-gel transition time was 3 min at 37 degrees C. The drug released over 3 h from the CS-HTCC/alpha,beta-GP thermosensitive hydrogel in artificial saliva pH 6.8. In addition, CS-HTCC/alpha,beta-GP thermosensitive hydrogel exhibited stronger antibacterial activity towards two periodontal pathogens (Porphyromonas gingivalis, P.g and Prevotella intermedia, P.i). CS-HTCC/alpha, beta-GP thermosensitive hydrogel was a considerable candidate as a local drug delivery system for periodontal treatment.

[Efficacy of the pharmacotherapy of secondary enuresis in children].

43 children, 8-16 years old, suffering from secondary nocturnal enuresis were treated using different schemes. The most effective treatment of patients with only nocturnal enuresis was using a complex of nootropic psychostimulant medications (Fesam, B vitamins, apilak, Ca Glycerophosphat) with xanthinol nicotinat and combined treatment with the help of day-light therapy (motivating and regimen measures).

Osteogenic differentiation of rat bone marrow stromal cells cultured on Arg-Gly-Asp modified hydrogels without dexamethasone and beta-glycerol phosphate.

In this study, we investigated the effect of signaling peptides incorporated into oligo(poly(ethylene glycol) fumarate) (OPF) hydrogels on in vitro differentiation and mineralization of marrow stromal cells (MSCs) cultured in media without soluble osteogenic supplements (dexamethasone and beta-glycerol phosphate). When MSCs were cultured for 16 days on OPF hydrogels modified with Arg-Gly-Asp (RGD) containing peptides, the normalized cell number was dependent on the peptide concentration between days 0 and 5 and reached comparable values at day 10 regardless of the concentration. The alkaline phosphatase (ALP) activity of MSCs on the peptide-modified OPF hydrogels was also concentration-dependent: ALP activity showed peaks on day 10 or day 13 on OPF hydrogels modified with 2.0 and 1.0 micromol peptide/g, which were significantly greater than those on the OPF hydrogels modified with 0.1 micromol peptides/g or no peptide. A characteristic marker of osteoblastic differentiation, osteopontin (OPN), was detected for all the test groups. However, OPN secretion between days 0 and 10 was significantly higher on the peptide modified hydrogels compared to that on tissue culture-treated polystyrene. Taken together, the results indicate that the presence of signaling peptide allows for a favorable microenvironment for MSCs to differentiate into osteoblasts and produce mineralized matrix, although the soluble factors may further enhance calcium deposition. These findings further support the usefulness of OPF hydrogels as scaffolds for guided bone regeneration, and represent an initial step in exploring the complex relationship between soluble and insoluble factors in osteogenic differentiation on biodegradable materials.

Calcium and phosphorus balance of extremely preterm infants with estradiol and progesterone replacement.

Infants born extremely prematurely are deprived of the placental supply of estradiol (E2) and progesterone (Prog) at an earlier developmental stage compared to an infant born at term. We hypothesized that the retention of Ca (calcium) and P (phosphorus) would be improved by an E2 and Prog replacement. Twenty female infants with a mean gestational age of 26.6 weeks (+/-1.5 SD) and a mean birth weight of 744 g (+/-156) were enrolled in a randomized controlled pilot study. One group received an E2 and Prog replacement to maintain intrauterine plasma concentrations of E2 and Prog and the other group served as control. When intake of formula was at least 100 mL/kg/d, a 3-day Ca and P balance study was performed. Ca and P intake was increased individually until both elements were excreted in the urine. The mean Ca and P retention was 4.21 (+/-1.75) mMol/kg/d (58% of intake) and 2.66 (+/-1.01) mMol/kg/d (80%) in the replaced group and 3.39 (+/-1.69) mMol/kg/d (56%) and 2.03 (+/-0.79) mMol/kg/d (71%) in the control group, respectively. In this pilot study the retention of Ca and P was not improved by an E2 and Prog replacement.

A fortifier comprising protein, vitamins, and calcium-glycerophosphate for preterm human milk.

BACKGROUND: The infant's own mother's milk, fortified with proteins, minerals, and vitamins, is considered the best food for low-birth-weight infants. This paper describes the process to obtain a liquid human milk fortifier. METHODS: The fortifier comprises a protein concentrate, calcium, phosphate, and zinc salts, as well as vitamins A and D. A powdered whey protein extracted from bovine milk was concentrated from 31.5-76.8 g/100 g using repetitive dialysis. The protein concentrate was dissolved in a 0.2 M phosphate buffer pH 7.4 and mixed with calcium-glycerophosphate and calcium-gluconate, vitamins A and D, folic acid, and zinc. Each 10 mL of this liquid fortifier has 0.78 g protein, 53 mg calcium, 36 mg phosphate, and 0.93 mg zinc. RESULTS: Repetitive dialysis did not modify the protein structure as demonstrated by electrophoresis. A total of 95% of lactose content was discarded. Enriching human milk using this human milk fortifier increased the concentration per deciliter of all added nutrients; proteins increased from 1.68-2.35 g, calcium from 26-90 mg, and phosphorus, from 15-51 mg. CONCLUSIONS: A liquid human milk fortifier was successfully manufactured using a noncomplex procedure. An intake of 180-200 mL/kg/day of the fortified human milk by the premature infant would satisfy the infant's nutritional requirements and achieve expected growth and development.

Randomized trial of calcium glycerophosphate-supplemented infant formula to prevent lead absorption.

BACKGROUND: Although additional dietary calcium is recommended frequently to reduce the risk of lead poisoning, its role in preventing lead absorption has not been evaluated clinically. OBJECTIVE: The objective was to determine the safety and to estimate the size of the effect of calcium- and phosphorus-supplemented infant formula in preventing lead absorption. DESIGN: One hundred three infants aged 3.5-6 mo were randomly assigned to receive iron-fortified infant formula (465 mg Ca and 317 mg P/L) or the same formula with added calcium glycerophosphate (1800 mg Ca and 1390 mg P/L) for 9 mo. RESULTS: There was no significant difference between groups in the mean ratio of urinary calcium to creatinine, serum calcium and phosphorus, or change in iron status (serum ferritin, total iron binding capacity). At month 4, the median (+/-SD) increase from baseline in blood lead concentration for the supplemented group was 57% of the increase for the control group (0.04 +/- 0.09 compared with 0.07 +/- 0.10 micromol/L; P = 0.039). This effect was attenuated during the latter half of the trial, with an overall median increase in blood lead concentration from baseline to month 9 of 0.12 +/- 0.13 micromol/L for the control group and 0.10 +/- 0.18 micromol/L for the supplemented group (P = 0.284). CONCLUSIONS: Supplementation did not have a measurable effect on urinary calcium excretion, calcium homeostasis, or iron status. The significant effect on blood lead concentrations during the first 4 mo was in the direction expected; however, because this was not sustained throughout the 9-mo period we cannot conclude that the calcium glycerophosphate supplement prevented lead absorption in this population.

Glycero- vs glucose-phosphate in parenteral nutrition of premature infants: a comparative in vitro evaluation of calcium/phosphorus compatibility.

In total parenteral nutrition (TPN) of premature infants, glycero- and glucose-phosphate have been recommended, and clinically used, because of their considerable compatibility with calcium. However, a systematic comparative in vitro assessment of the therapeutic potential and safety of these substances has not yet been provided. We investigated the stability of TPN solutions containing calcium-gluconate and glycero- or glucose-phosphate in high concentrations. Evaluation was performed by visual inspection, absorptiometry, light microscopy, measurement of pH, and determination of calcium concentration before and after microfiltration. Even under circumstances promoting precipitation of calcium and phosphate--such as body temperature, relatively high pH, and concentrations of calcium and phosphorus exceeding those necessary to provide intrauterine accretion rates, all but one of the examined TPN admixtures remained stable. Our data suggest that the use of glycero-phosphate, and particularly glucose-phosphate, together with calcium-gluconate, is an uncomplicated and safe procedure to administer simultaneously high amounts of calcium and phosphorus in TPN of premature infants.

Calcium glycerophosphate as a source of calcium and phosphorus in total parenteral nutrition solutions.

Calcium glycerophosphate (CaGP) was tested as an alternative to calcium gluconate (CaGluc) and potassium mono- and dibasic phosphate (KPhos) as a source of Ca and P in total parenteral nutrition (TPN) solutions for piglets. Four-day-old piglets were infused for 7 days with a TPN solution that provided either 4.2 mmol Ca and 2.1 mmol P/kg/24 h as CaGluc and KPhos (the maximum quantities that can be provided using these sources), or 15.0 mmol Ca and 15.0 mmol P/kg/24 h as CaGP. Ca and P retentions were more than six times greater (p less than 0.01) in the piglets receiving CaGP (14.5 +/- 0.2 vs 2.2 +/- 0.3 mmol Ca/kg/24 h and 13.3 +/- 0.4 vs 2.4 +/- 0.1 mmol P/kg/24 h) (Mean +/- SEM). The ratio of Ca to fat-free dry weight, an indicator of bone mineralization, was significantly higher (p less than 0.05) in the humerus (174.8 +/- 2.2 vs 147.2 +/- 6.7) and femur (158.3 +/- 4.8 vs 130.1 +/- 7.8) in the CaGP group. This study showed that CaGP is efficiently used as a source of Ca and P in TPN solutions for piglets. The results suggest that the use of CaGP as the source of Ca and P in TPN solutions may prevent the development of the undermineralized bone seen in low-birth weight infants nourished intravenously.

Severe selective magnesium malabsorption: tests of tolerance of oral magnesium supplements.

Since his birth, we have been monitoring a 12-year-old boy suffering from selective severe magnesium malabsorption. Our essential problem is to prepare a form of galena with acceptable taste, tolerated by the digestive tract and well absorbed; also, the carrier compound must not cause short- or long-term side effects. An additional factor is the steadily increasing need for magnesium from 1 mmol/kg.d at 1 year to 14 mmol/kg.d at present age (345 mg/kg.d). The galena forms currently on sale were, with the exception of lactate and pyrollidone carboxylate, immediately rejected since they contain insufficient Mg2+. Following short trials resulting in diarrhoea, the other two preparations were also rejected. We then constituted - and also abandoned - our own galena compounds: aspartate (bitterness), aspartate + glycerophosphate (GLP) (bitterness), glutamate + GLP ('Chinese restaurant syndrome' and fear of the long term toxic effect of the glutamate), gluconate (excessive volume: 11/1 proportion with Mg2+). A recent test featuring GLP of Mg 40 g + cocoa butter 40 g + cocoa 10 g, brought about vomiting and diarrhoea, and was not adequately absorbed. The best tolerated formula is: Mg GLP 21.33 g; saccharose 6 g; aspartam 1 g; gelatin 0.5 g; citric acid, conserving agent, fruity aroma; water: qs 100 g. Such composition yields a caramel cream absorbed in five small portions, at a daily quantity of 375 g (80 g GLP Mg, 10 g Mg2+). Vitamin B6, which promotes intestinal absorption of magnesium, must be given separately in tablet form at a dose of 1 g/d, since it causes nausea if it is included in the Mg preparation.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium homeostasis after parathyroidectomy in normal and shocked states.

The natural history of parathyroidectomy was studied for 75 weeks in two dogs. After parathyroidectomy, the dogs required intravenous and intramuscular calcium supplementation for 1 week. Despite calcium supplementation, in 2 weeks the ionized calcium (Ca++) level fell from 4.67 mg/dl to 2.39 mg/dl. The Ca++ level rose to 4.25 mg/dl by 7 weeks after which the intramuscular calcium supplement was gradually weaned so that no calcium was given after 20 weeks. The Ca++ level stabilized at 3.15 to 3.25 mg/dl after 20 weeks. Postoperative parathormone (PTH) levels remained low. The response to hemorrhagic shock in these two calcium-independent dogs was compared with that seen in two calcium-dependent dogs 4 weeks after parathyroidectomy and to that seen in two euparathyroid dogs. Shock caused a sharp decrease in Ca++ in all animals that had parathyroid ectomy. Prostaglandin E2 (PGE2) was elevated preoperatively in these dogs and fell markedly during shock. Ca++ remained normal and PGE2 increased slightly after shock in the euparathyroid dogs. Cardiac output rose with resuscitation in the euparathyroid dogs but remained constant in the calcium-dependent dogs and increased slightly in the calcium independent parathyroidectomized animals. PTH levels were low in the parathyroidectomy groups and did not react to shock. PTH increased markedly after resuscitation in the euparathyroid dogs, suggesting its role as an acute-phase hormone. All levels returned to baseline levels within 3 days after shock. Adaptation to hypocalcemia occurs in parathyroidectomized dogs and involves PGE2 as well as other factors. Hemorrhagic shock exceeds this compensatory response which in euparathyroid dogs involves active PTH release in response to hypocalcemia.

Role of organic phosphate in mineralization of bone in vitro.

Calvarial periostea were dissected from 17-day-old embryonic chicks and folded with the osteogenic cells in apposition. The folded explants were cultured for up to six d on serum and plasma clots or in serum-free hormone-supplemented completely-defined medium. Osteoid consistently formed in such cultures in both types of media, and this osteoid mineralized when appropriate levels of beta-glycerophosphate were added to each type of medium. The data presented suggest that the levels of organic phosphates as a limiting factor in the initiation of mineralization of bone in vitro.