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PubMed1998

[Alpha-hemolytic streptococci and root canal irrigants. An evaluation of the bactericidal efficacy of sodium hypochlorite and chlorhexidine gluconate plus cetrimide].

BACKGROUND AND AIMS: The main bacterial species present in pulpal and periapical microbic flora is alpha-hemolytic streptococci. They are regarded as facultative anaerobes which prefer to grow in anaerobiosis. Canal irrigation plays an important role in the success of endodontic treatment given that, on the one hand, it encourages the gradual elimination of the smear layer, and on the other it neutralises microbic flora in the root canal. The aim of this study was to test the microbiological efficacy of sodium hypochlorite 1% and s new generation irrigant based on chlorhexidine 0.2% and cetrimide 0.2%. METHODS: The test was performed on the following alpha-hemolytic streptococci bacteria (Dasit, Cornaredo, Italy): Streptococcus mitis ATCC 9811; Streptococcus mutans ATCC 35668; Streptococcus salivarius ATCC 13419; Streptococcus sanguis ATCC 10556. The working concentration (CFU/ml) was defined as 0.5 Mc Farland which corresponds to a concentration of microorganisms of approximately 1.5 x 10(8) bacteria. The following canal irrigants were used: 1) cetrimide 0.2% + chlorhexidine 0.2% (Cetrexidin Vebas, S. Giuliano Milanese, Italy); 2) NaOCl 1% (Ogna, Milan, Italy). Each individual substance remained in contact with the bacterial species used in the test for 10'-20'-30'. RESULTS: The results obtained show the bactericidal efficacy of both the irrigants used, even after a short period of contact. CONCLUSIONS: This does not mean that all irrigants are equal and/or promise the same results. This was a microbiological study, but it is nonetheless important to take other variables into account, such as contact time. Moreover, in order to increase the probabilities for the success of endodontic treatment, canal irrigants must also present other characteristics, namely: biocompatibility, scarce toxicity, high proteolytic power.

Anti-Bacterial Agents↗
PubMed1997

Multi-Ion mechanism for ion permeation and block in the cystic fibrosis transmembrane conductance regulator chloride channel.

The mechanism of Cl ion permeation through single cystic fibrosis transmembrane conductance regulator (CFTR) channels was studied using the channel-blocking ion gluconate. High concentrations of intracellular gluconate ions cause a rapid, voltage-dependent block of CFTR Cl channels by binding to a site approximately 40% of the way through the transmembrane electric field. The affinity of gluconate block was influenced by both intracellular and extracellular Cl concentration. Increasing extracellular Cl concentration reduced intracellular gluconate affinity, suggesting that a repulsive interaction occurs between Cl and gluconate ions within the channel pore, an effect that would require the pore to be capable of holding more than one ion simultaneously. This effect of extracellular Cl is not shared by extracellular gluconate ions, suggesting that gluconate is unable to enter the pore from the outside. Increasing the intracellular Cl concentration also reduced the affinity of intracellular gluconate block, consistent with competition between intracellular Cl and gluconate ions for a common binding site in the pore. Based on this evidence that CFTR is a multi-ion pore, we have analyzed Cl permeation and gluconate block using discrete-state models with multiple occupancy. Both two- and three-site models were able to reproduce all of the experimental data with similar accuracy, including the dependence of blocker affinity on external Cl (but not gluconate) ions and the dependence of channel conductance on Cl concentration. The three-site model was also able to predict block by internal and external thiocyanate (SCN) ions and anomalous mole fraction behavior seen in Cl/SCN mixtures.

Animals↗
PubMed1981

Kinetic analysis of the inhibition of anion transport in sarcoplasmic reticulum vesicles by a disulfonic stilbene derivative. Measurement of the change in chloride-diffusion potential by using a fluorescent cyanine dye.

The characterization of the anion transport system in sarcoplasmic reticulum (SR) vesicles was performed by kinetic analysis of the reversible inhibition of gluconate efflux by a disulfonic stilbene derivative; 4-acetamido-4'-isothiocyano-stilbene-2,2'-disulfonate (SITS). The gluconate efflux in SR vesicles was measured by following the change in Cl- ion-diffusion potential due to the mutual diffusion of Cl- and gluconate- using a potential probe; 3,3'-dipropylthiadicarbocyanine iodide (diS-C3-(5)). The main results are as follows. (1) Gluconate efflux was increased by intravesicular gluconate- and was decreased by both extravesicular gluconate- and extravesicular Cl-. (2) Gluconate efflux was depressed when membrane potential became inside-negative. (3) SITS reacted with the site of the anion transport system from the outside of the vesicles and one molecule of SITS inhibited each transport unit. (4) Extravesicular Cl- competed with SITS at the common site of the anion transport system. The dissociation constants for Cl- and SITS are 70 mM and 0.048 microM, respectively. (5) The inhibition of gluconate efflux by SITS was noncompetitive with both intravesicular gluconate and extravesicular gluconate. These results suggest that the anion transport system in SR vesicles can be described by a carrier-mediated transport model in which anions are transported by a mobile transport site accompanied by a net negative charge.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗
PubMed1973

Glucolysis in Pseudomonas putida: physiological role of alternative routes from the analysis of defective mutants.

A number of mutants in which glucolysis is impaired have been isolated from Pseudomonas putida. The study of their behavior shows that this organism possesses a single glucolytic pathway with physiological significance. The first step of the pathway consists in the oxidation of glucose into gluconate. Two proteins with glucose dehydrogenase activity appear to exist in P. putida but the reasons for this duplicity are not clear. The process continues with the formation of 2-ketogluconate which is in turn converted into gluconate-6-phosphate. This is proved by the fact that mutants unable to form gluconate-6-phosphate from 2-ketogluconate show extremely slow growth on glucose or gluconate (generation times are increased more than 100 times). Other possible routes for the conversion of glucose into gluconate-6-phosphate, the glucose-6-phosphate pathway, or the direct phosphorylation of the gluconate formed by glucose oxidation are only minor shunts in P. putida. The Entner-Doudoroff enzymes, which catalyze the conversion of gluconate-6-phosphate into pyruvate and triosephosphate, appear to be essential to grow on glucose and also on gluconate and 2-ketogluconate. A significative role of the pentose route in the catabolism of these substrates is not apparent from this study. In contrast, P. putida strains showing no activity of the Entner-Doudoroff enzymes grow readily on fructose, although there is evidence that this hexose is at least partially catabolized via gluconate-6-phosphate.

Culture Media↗
PubMed1975

Effect of temperature on the activity and synthesis of glucose-catabolizing enzymes in Pseudomonas fluorescens.

The activity of the enzymes of the oxidative non-phosphorylated pathway, glucose and gluconate dehydrogenases, were not significantly affected by changes in the assay temperature. Both enzymes demonstrated only a threefold difference in activity when compared at assay temperatures of 30 degrees C and 5 degrees C. In contrast, the enzymes involved in the direct phosphorylation and catabolism of glucose or its oxidation products, gluconate and 2-ketogluconate, exhibited a more pronounced response to decreasing assay temperatures. At least one enzyme in each pathway, involved in the direct phosphorylation and catabolism of glucose or 2-ketogluconate (2KG), demonstrated an eightfold decrease in activity with a decrease in assay temperature from 30 degrees C to 5 degrees C. A similar decrease in assay temperature resulted in a fivefold decrease in activity of the enzymes involved in the direct phosphorylation and catabolism of gluconate. The observed differential effect of temperature on the activity of the enzymes of glucose catabolism and on the accumulation of direct oxidation products during growth with glucose in P. fluorescens E-20 is discussed. Growth with glucose at 5 or 20 degrees C resulted in high induced levels of all glucose-catabolizing enzymes examined when compared with the levels of these same enzymes in pyruvate-grown cells. However, only low levels of glucose dehydrogenase were detected during growth at 30 degrees C with glucose, gluconate, or 2-KG. Similarly, only low levels of gluconate dehydrogenase were detected during growth with glucose at 30 degrees C, although a weak induction was observed during growth with gluconate or 2-KG at 30 degrees C. The levels of 2-KG kinase plus KPG reductase during growth at 30 degrees C were undetectable with glucose, weakly induced with gluconate, and fully induced with 2-KG. High induced levels of glucose dehydrogenase, gluconate dehydrogenase, and 2-KG kinase plus KPG reductase were present during growth at 20 degrees C with glucose or 2-KG. The low levels of glucose and gluconate dehydrogenases present at a growth temperature of 30 degrees C was not due to heat lability of the enzymes at this temperature. The low amounts of these two enzymes during growth with glucose at 30 degrees C probably prevented sufficient inducer(s) formation from glucose to allow induction of enzymes of 2-KG catabolism. The results demonstrated that temperature may regulate the pathways of glucose dissimilation by regulating, either directly or indirectly, the activity and synthesis of the enzymes involved in these pathways.

Alcohol Oxidoreductases↗
PubMed1991

Pathways for metabolism of ketoaldonic acids in an Erwinia sp.

The pathways involved in the metabolism of ketoaldonic acids by Erwinia sp. strain ATCC 39140 have been investigated by use of a combination of enzyme assays and isolation of bacterial mutants. The catabolism of 2,5-diketo-D-gluconate (2,5-DKG) to gluconate can proceed by two separate NAD(P)H-dependent pathways. The first pathway involves the direct reduction of 2,5-DKG to 5-keto-D-gluconate, which is then reduced to gluconate. The second pathway involves the consecutive reduction of 2,5-DKG to 2-keto-L-gulonate and L-idonic acid, which is then oxidized to 5-keto-D-gluconate, which is then reduced to gluconate. Gluconate, which can also be produced by the NAD(P)H-dependent reduction of 2-keto-D-gluconate, is phosphorylated to 6-phosphogluconate and further metabolized through the pentose phosphate pathway. No evidence was found for the existence of the Entner-Doudoroff pathway in this strain.

Erwinia↗
PubMed1985

Effects of anions on cellular volume and transepithelial Na+ transport across toad urinary bladder.

The effects of complete substitution of gluconate for mucosal and/or serosal medium Cl- on transepithelial Na+ transport have been studied using toad urinary bladder. With mucosal gluconate, transepithelial potential difference (VT) decreased rapidly, transepithelial resistance (RT) increased, and calculated short-circuit current (Isc) decreased. Calculated ENa was unaffected, indicating that the inhibition of Na+ transport was a consequence of a decreased apical membrane Na+ conductance. This conclusion was supported by the finding that a higher amiloride concentration was required to inhibit the residual transport. With serosal gluconate VT decreased, RT increased and Isc fell to a new steady-state value following an initial and variable transient increase in transport. Epithelial cells were shrunken markedly as judged histologically. Calculated ENa fell substantially (from 130 to 68 mV on average). Ba2+ (3 mM) reduced calculated ENa in Cl- Ringer's but not in gluconate Ringer's. With replacement of serosal Cl- by acetate, transepithelial transport was stimulated, the decrease in cellular volume was prevented and ENa did not fall. Replacement of serosal isosmotic Cl- medium by a hypo-osmotic gluconate medium (one-half normal) also prevented cell shrinkage and did not result in inhibition of Na+ transport. Thus the inhibition of Na+ transport can be correlated with changes in cell volume rather than with the change in Cl-per se. Nystatin virtually abolished the resistance of the apical plasma membrane as judged by measurement of tissue capacitance. With K+ gluconate mucosa, Na+ gluconate serosa, calculated basolateral membrane resistance was much greater, estimated basolateral emf was much lower, and the Na+/K+ basolateral permeability ratio was much higher than with acetate media. It is concluded the decrease in cellular volume associated with substitution of serosal gluconate for Cl results in a loss of highly specific Ba2+-sensitive K+ conductance channels from the basolateral plasma membrane. It is possible that the number of Na+ pump sites in this membrane is also decreased.

Animals↗
PubMed1997

An evaluation of five protocols for surgical handwashing in relation to skin condition and microbial counts.

Five protocols for surgical handwashing (scrubbing) were evaluated for their efficiency of removal of micro-organisms and their drying effect on the skin. The scrubbing protocols tested were: (1) an initial scrub of 5 min and consecutive scrubs of 3.5 min with chlorhexidine gluconate 4% (CHG-5); (2) an initial scrub of 3 min and consecutive scrubs of 2.5 min with chlorhexidine gluconate 4% (CHG-3); (3) an initial scrub of 3 min and consecutive scrubs of 2.5 min with povidone iodine 5% and triclosan 1% (PI-3); (4) an initial scrub of 2 min with chlorhexidine gluconate 4% followed by a 30 s application of isopropanol 70% and chlorhexidine gluconate 0.5%, and a 30 s application of isopropanol 70% and chlorhexidine gluconate 0.5% for consecutive scrubs (IPA); and (5) an initial scrub of 2 min with chlorhexidine gluconate 4% followed by a 30 s application of ethanol 70% and chlorhexidine gluconate 0.5%, and a 30 s application of ethanol 70% and chlorhexidine gluconate 0.5% for consecutive scrubs (EA). A convenience sample of 23 operating theatre nurses completed each scrub protocol for one week in a randomized order. A week of normal work activities intervened between each protocol. Subjects were assessed before commencing and after completing the week of each protocol to determine changes in the microbial counts and skin condition of the hands. Specimens for microbial analysis were collected before, immediately after and 2 h after an initial scrub, and 2 h after a consecutive scrub. The CHG-5, CHG-3 and PI-3 protocols, which used detergent-based antiseptics only, were compared with protocols incorporating an alcohol-based antiseptic (IPA and EA). The protocols incorporating alcohol-based antiseptics and the CHG-5 protocol were generally associated with the lowest post-scrub numbers of colony forming units (cfu). No difference between the CHG-5 protocol and the alcohol-based antiseptics was found at the beginning of the test week, but after exclusive use of the respective protocols for a week, the alcohol-based antiseptics were associated with significantly lower cfu numbers in two out of the three post-scrub samples (P = 0.003, P = 0.035). Although virtually no statistically significant differences in skin condition were found, many subjects reported the alcohol-based antiseptic protocols to be less drying on the skin. The findings of this study support the proposition that a scrub protocol using alcohol-based antiseptics is as effective and no more damaging to skin than more time-consuming, conventional methods using detergent-based antiseptics.

1-Propanol↗
PubMed1982

Production of 2-Keto-l-Gulonic Acid from d-Glucose by Two-Stage Fermentation.

A practical method for the production of calcium 2-keto-l-gulonate (an intermediate in the Reichstein synthesis of l-ascorbic acid) from d-glucose has been established by using a two-stage fermentation system. d-Glucose was first converted to calcium 2,5-diketo-d-gluconate by a mutant strain of Erwinia sp. in a medium containing d-glucose, corn steep liquor, (NH(4))(2)HPO(4), and CaCO(3). After a 26-h cultivation, 328.6 mg of calcium 2,5-diketo-d-gluconate per ml was obtained, with a 94.5% yield from d-glucose. This broth was used directly for the next conversion without removal of cells by treatment with sodium dodecyl sulfate. The stereospecific reduction of calcium 2,5-diketo-d-gluconate to calcium 2-keto-l-gulonate was performed with a mutant strain of Corynebacterium sp. When the cell growth reached a maximum (about 16 h) in a medium containing d-glucose, corn steep liquor, NaNO(3), KH(2)PO(4), and trace elements, NaNO(3) was added to the culture, and then the calcium 2,5-diketo-d-gluconate broth was fed over a period of about 50 h. Since the mutant strain requires a hydrogen donor for reduction, the calcium 2,5-diketo-d-gluconate broth was mixed with d-glucose before being fed. The results of four two-stage fermentations in 10-m conventional fermentors showed that an average of 106.3 mg of calcium 2-keto-l-gulonate per ml was obtained, with a 84.6% yield from d-glucose, the starting material of calcium 2,5-diketo-d-gluconate production. Calcium 2-keto-l-gulonate was stable in the broth. Neither 2-keto-d-gluconic acid nor 5-keto-d-gluconic acid was detected in the final broth.

Journal Article↗
PubMed2002

New developments in oxidative fermentation.

Oxidative fermentations have been well established for a long time, especially in vinegar and in L-sorbose production. Recently, information on the enzyme systems involved in these oxidative fermentations has accumulated and new developments are possible based on these findings. We have recently isolated several thermotolerant acetic acid bacteria, which also seem to be useful for new developments in oxidative fermentation. Two different types of membrane-bound enzymes, quinoproteins and flavoproteins, are involved in oxidative fermentation, and sometimes work with the same substrate but produce different oxidation products. Recently, there have been new developments in two different oxidative fermentations, D-gluconate and D-sorbitol oxidations. Flavoproteins, D-gluconate dehydrogenase, and D-sorbitol dehydrogenase were isolated almost 2 decades ago, while the enzyme involved in the same oxidation reaction for D-gluconate and D-sorbitol has been recently isolated and shown to be a quinoprotein. Thus, these flavoproteins and a quinoprotein have been re-assessed for the oxidation reaction. Flavoprotein D-gluconate dehydrogenase and D-sorbitol dehydrogenase were shown to produce 2-keto- D-gluconate and D-fructose, respectively, whereas the quinoprotein was shown to produce 5-keto- D-gluconate and L-sorbose from D-gluconate and D-sorbitol, respectively. In addition to the quinoproteins described above, a new quinoprotein for quinate oxidation has been recently isolated from Gluconobacter strains. The quinate dehydrogenase is also a membrane-bound quinoprotein that produces 3-dehydroquinate. This enzyme can be useful for the production of shikimate, which is a convenient salvage synthesis system for many antibiotics, herbicides, and aromatic amino acids synthesis. In order to reduce energy costs of oxidative fermentation in industry, several thermotolerant acetic acid bacteria that can grow up to 40 degrees C have been isolated. Of such isolated strains, some thermotolerant Acetobacter species were found to be useful for vinegar fermentation at a high temperature such 38-40 degrees C, where mesophilic strains showed no growth. They oxidized higher concentrations of ethanol up to 9% without any appreciable lag time, while alcohol oxidation with mesophilic strains was delayed or became almost impossible under such conditions. Several useful Gluconobacter species of thermotolerant acetic acid bacteria are also found, especially L-erythrulose-producing strains and cyclic alcohol-oxidizing strains. Gluconobacter frateurii CHM 43 is able to rapidly oxidize meso-erythritol at 37 degrees C leading to the accumulation of L-erythrulose, which may replace dihydroxyacetone in cosmetics. G. frateuriiCHM 9 is able to oxidize cyclic alcohols to their corresponding cyclic ketones or aliphatic ketones, which are known to be useful for preparing many different physiologically active compounds such as oxidized steroids or oxidized bicyclic ketones. The enzymes involved in these meso-erythritol and cyclic alcohol oxidations have been purified and shown to be a similar type of membrane-bound quinoproteins, consisting of a high molecular weight single peptide. This is completely different from another quinoprotein, alcohol dehydrogenase of acetic acid bacteria, which consists of three subunits including hemoproteins.

Acetic Acid↗
PubMed1997

Use of low temperature and high K+ incubation media for in vitro tissue preparation for X-ray microanalysis.

Incubation of tissue slices in physiological buffers gives rise to significant changes in the intracellular ion concentrations, which may disturb subsequent X-ray microanalysis. In the present study it was attempted to design incubation conditions that retain the in vivo conditions better. The following variables were investigated: (1) exchange of Na+ in the incubation medium for K+, and exchange of Cl- for the less permeable gluconate anion; (2) incubation at 4 degrees C rather than at 37 degrees C; and (3) addition of dextran to the incubation medium. Brief exposure (a few seconds) of liver slices to a buffer causes changes in the intracellular Na, Cl and K concentrations, depending on the ionic composition of the buffer. Incubation in a normal physiological (high NaCl) buffer at 37 degrees C results in a further increase of Na and Cl and a further decrease in K in liver cells. The changes reach a maximum at 30 min and the concentrations then remain stable throughout a 2-h incubation. Incubation in sodium gluconate medium or addition of dextran to the physiological buffer somewhat reduces the changes in the intracellular ion composition (compared to the standard physiological incubation medium). Incubation in potassium gluconate medium results in a decrease in cellular Na and an increase in K. Quantitative morphological studies show that tissue oedema is observed to the same extent in hepatocytes incubated in sodium gluconate, potassium gluconate and physiological buffer containing 10% dextran. However, these buffers cause significantly less cell oedema than the physiological (high NaCl) buffer. Incubation of liver, cerebral cortex or submandibular gland slices in physiological (high NaCl) solutions at 4 degrees C for 4 h caused a more extensive increase in Na+ and decrease in K+ than incubation at 37 degrees C for 2 h. This suggests inhibition of the Na+, K(+)-ATPase under these conditions. As compared to incubation at 37 degrees C for 2 h, tissues incubated in potassium gluconate buffer at 4 degrees C for 4 h have a cellular K concentration closer to the in situ value. Cholinergic stimulation of tissue slices from cerebral cortex and submandibular gland at room temperature for 1 min shows the best physiological response in tissue slices preincubated at 4 degrees for 4 h in high KCl, potassium gluconate and high NaCl, in this order. The response can, however, only be seen, when cholinergic stimulation is carried out in a standard physiological buffer with a high NaCl concentration. It is concluded that in vitro storage of tissue for X-ray microanalysis is best carried out at 4 degrees C in a solution with a high K+ concentration.

Absorption↗
PubMed2005

Parenteral iron treatment induces MCP-1 accumulation in plasma, normal kidneys, and in experimental nephropathy.

INTRODUCTION: Monocyte chemoattractant protein-1 (MCP-1) promotes renal inflammation, thereby contributing to acute and chronic nephropathies. Its production is stimulated by oxidative stress. Thus, this study tested whether pro-oxidant iron/carbohydrate complexes, used to treat iron deficiency, induce MCP-1 in renal/extrarenal tissues, in plasma, and in the setting of experimental nephropathy. METHODS: CD-1 mice received 2 mg of intravenous iron [complexed with dextran (iron dextran), sucrose (iron sucrose), or gluconate (iron gluconate)]. Renal MCP-1 and/or its mRNA were measured 3 hours to 7 days post-iron injection. Iron effects on liver, lung, spleen, and heart MCP-1 mRNA, and on peritoneal lavage fluid MCP-1 concentrations were assessed. Iron pretreatment effects on MCP-1 levels in unilaterally obstructed kidneys vs. contralateral kidneys were determined. Finally, iron gluconate's influence on proximal tubule [human kidney-2 (HK-2)] cell MCP-1 levels was assessed. RESULTS: Iron sucrose (the primary test agent) markedly increased plasma and renal MCP-1 levels. It also induced multiorgan MCP-1 mRNA increments (liver > spleen > kidney > lung > heart). Iron gluconate was more potent than iron sucrose; conversely, iron dextran had no discernible effect. The iron dextran and iron sucrose-induced renal MCP-1 mRNA increments ( approximately 4x) were persistent, lasting for at least 3 to 7 days. Iron gluconate raised MCP-1 levels in peritoneal lavage fluid. It also doubled MCP-1 in unilaterally obstructed kidneys (ureteral ligation) without altering contralateral (control kidney) MCP-1 content. Iron gluconate raised HK-2 cell MCP-1, implying a direct proximal tubule effect. CONCLUSION: Iron sucrose and iron gluconate (but not iron dextran) can induce MCP-1 generation in renal and extrarenal tissues, possibly via transcriptional events. This may dramatically impact renal disease-induced MCP-1 increments. Finally, iron can increase peritoneal lavage fluid MCP-1 levels. Whether the above changes have implications for renal disease progression, and/or for peritoneal inflammation/peritoneal dialysis efficiency, are issues which may need to be addressed.

Acute Disease↗
PubMed1975

The specificity of oxidase and kinase preparations from Pseudomonas fluorescens towards deoxyfluoromonosaccharides.

With partially purified enzyme preparations from cell-free extracts of Pseudomonas fluorescens, 3-deoxy-3-fluoro-D-glucose and 3-deoxy-3-fluoro-D-gluconic acid are substrates for glucose oxidase (EC 1.1.3.4.) and gluconate dehydrogenase (EC 1.1.99.3), with K-m values 18.2 mM and 11.8 mM, respectively. The same enzymes that oxidize glucose and gluconic acid probably oxidize 3-deoxy-3-fluoro-D-glucose and 3-deoxy-3-fluoro-D-gluconic acid. The latter fluorinated carbohydrates and the presumed formation of 3-deoxy-3-fluoro-2-keto-D-gluconic acid, which has been isolated as a calcium salt and characterizied, are not substrates for gluconokinase (EC 2.7.1.12). Both 3-deoxy-3-fluoro-D-glucose and 3-deoxy-3-fluoro-D-gluconic acid act as competitive inhibitors of this enzyme preparation for gluconate, with K-i values 47.5 mM and 14.8 mM, respectively.

Alcohol Oxidoreductases↗
PubMedDate not supplied

Treatment of acute hypocalcemia in critically ill multiple-trauma patients.

BACKGROUND: Recent data indicate that critically ill, adult multiple trauma patients receiving specialized nutrition support commonly experience hypocalcemia (ionized serum calcium [iCa] < or =1.12 mmol/L). However, validated methods for the treatment of acute hypocalcemia are lacking. METHODS: The efficacy of a single dose of calcium gluconate using an empiric IV calcium gluconate graduated dosing regimen was evaluated in 37 patients. Patients with an iCa of 1-1.12 mmol/L (mild hypocalcemia) were provided 1-2 g of IV calcium gluconate. Patients with an iCa of <1 mmol/L (moderate to severe hypocalcemia) were given 2-4 g. The calcium gluconate was infused at a rate of 1 g/h in a small-volume admixture. Serum iCa determination was repeated on the following day. RESULTS: One to 2 g of IV calcium gluconate was effective in normalizing iCa for 23 out of 29 patients (79%) with mild hypocalcemia and 2-4 g was effective for 3 of 8 patients (38%) with moderate to severe hypocalcemia. The individual response to calcium therapy (g/d) or when normalized to body weight (mg/kg/d) was highly variable. CONCLUSIONS: One to 2 g of IV calcium gluconate were effective for most patients with mild hypocalcemia; however, treatment of moderate to severe hypocalcemia with 2-4 g of IV calcium gluconate was often unsuccessful. Further study with frequent serial ionized serum calcium and phosphorus determinations and electrocardiographic monitoring appears to be indicated for patients with moderate to severe hypocalcemia.

Acute Disease↗
PubMed2005

Determination of relative bioavailability of zinc in a petit suisse cheese using weight gain and bone zinc content in rats as markers.

The aim of the study was to determine the relative bioavailability of zinc gluconate stabilized with glycine in a Petit Suisse cheese from an infant dessert. Weight gain and bone zinc content were the nutritional responses evaluated for the diets of different zinc content: 2 ppm (basal) and 5, 10, and 30 ppm from zinc gluconate stabilized with glycine and zinc sulfate. Nonlinear regression analysis of the fitted curves for weight gain determined a relative zinc bioavailability of 100% for the Y max ratio and 96% for Ymax/t1/2 ratio for zinc gluconate stabilized with glycine (R2=0.7996 for zinc sulfate and 0.8665 for zinc gluconate stabilized with glycine). The slope ratio analysis from linear regression of femur zinc determined a relative zinc bioavailability of 93% for zinc gluconate stabilized with glycine (R 2=0.8693 for zinc sulfate and 0.8307 for zinc gluconate stabilized with glycine). Zinc gluconate stabilized with glycine has similar bioavailability as zinc sulfate in a Petit Suisse cheese nutritional matrix, with the advantage that the stabilized compound does not modify the sensorial characteristics of the fortified cheese.

Animals↗
PubMed1981

Regulation of pyruvate kinase by 6-phosphogluconate in isolated hepatocytes.

Isolated liver parenchymal cells from rats fed a 65% sucrose diet for 14 days were incubated in the presence and absence of 10(-6) M glucagon. The pyruvate kinase obtained from homogenates of the glucagon-treated cells displayed and increased Ks 0.5 for phosphoenolpyruvate (P-enolpyruvate), as well as an increased Ka 0.5 for 6-phosphogluconate (6-P-gluconate), compared to pyruvate kinase from untreated cells. Additionally, glucagon treatment decreased the maximal stimulation of pyruvate kinase by 6-P-gluconate by approximately two-thirds and decreased the Hill coefficient value of pyruvate kinase for 6-P-gluconate from 1.76 to 1.56. 6-Aminonicotinamide, an inhibitor of 6-P-gluconate dehydrogenase, increased 6-P-gluconate levels in isolated liver parenchymal cells three- to sevenfold, depending on the substrates present. The flux of P-enolpyruvate through pyruvate kinase was increased from 18 to 40% in these preparations and was highly correlated with the increase in 6-P-gluconate levels. The results suggest that 6-P-gluconate could regulate pyruvate kinase activity in the intact liver parenchymal cell. Furthermore, the activator would be of greatest importance in the lipogenic animal.

Animals↗
PubMed1999

Hemodynamic effects of ionized calcium in horses anesthetized with halothane or isoflurane.

OBJECTIVES: To evaluate the effects of halothane and isoflurane on cardiovascular function and serum total and ionized calcium concentrations in horses, and to determine whether administration of calcium gluconate would attenuate these effects. ANIMALS: 6 clinically normal adult Thoroughbreds. PROCEDURE: Catheters were inserted for measurement of arterial blood pressures, pulmonary arterial blood pressures, right ventricular pressure (for determination of myocardial contractility), right atrial pressure, and cardiac output and for collection of arterial blood samples. Anesthesia was then induced with xylazine hydrochloride and ketamine hydrochloride and maintained with halothane or isoflurane. An i.v. infusion of calcium gluconate was begun 75 minutes after anesthetic induction; dosage of calcium gluconate was 0.1 mg/kg of body weight/min for the first 15 minutes, 0.2 mg/kg/min for the next 15 minutes, and 0.4 mg/kg/min for an additional 15 minutes. Data were collected before, during, and after administration of calcium gluconate. RESULTS: Halothane and isoflurane decreased myocardial contractility, cardiac index, and mean arterial pressure, but halothane caused greater depression than isoflurane. Calcium gluconate attenuated the anesthetic-induced depression in cardiac index, stroke index, and maximal rate of increase in right ventricular pressure when horses were anesthetized with isoflurane. When horses were anesthetized with halothane, a higher dosage of calcium gluconate was required to attenuate the depression in stroke index and maximal rate of increase in right ventricular pressure; cardiac index was not changed with calcium administration. CONCLUSIONS AND CLINICAL RELEVANCE: I.v. administration of calcium gluconate may support myocardial function in horses anesthetized with isoflurane.

Anesthesia, Inhalation↗
PubMed1994

Comparison of topical magnesium and calcium treatment for dermal hydrofluoric acid burns.

STUDY OBJECTIVE: To compare topical preparations of magnesium and calcium in the treatment of dermal hydrofluoric acid burns. DESIGN: A randomized, blinded, controlled animal model study. SETTING: Animal care facility. TYPE OF PARTICIPANTS: New Zealand rabbits. INTERVENTIONS: Each rabbit was burned with hydrofluoric acid at four sites along the thoracolumbar spine. Equimolar amounts of calcium gluconate, magnesium gluconate, and a magnesium hydroxide antacid were added into a lubricating jelly. The jelly alone was a control preparation. After a water rinse, the burns were massaged with the gels for 1 minute five times; at 4 and 20 minutes and at 1, 4, and 24 hours. Each rabbit served as its own control by receiving all four treatments. MEASUREMENTS AND MAIN RESULTS: Burn diameter and burn surface area diminished over time, but there were no statistically significantly differences among the treatments. Burn ranking and burn rating of severity also did not demonstrate differences. The histologic analysis of the burns, however, demonstrated that calcium gluconate-treated burns were less severe and more superficial than the control and magnesium gluconate-treated burns; the magnesium hydroxide antacid-treated burns were not statistically different compared to the calcium gluconate-treated burns. CONCLUSION: Topical calcium gluconate is an efficacious treatment for dermal hydrofluoric acid burns. Further research is needed to determine the role of magnesium-containing antacids in the treatment of hydrofluoric acid burns.

Administration, Cutaneous↗