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At least 307 records · Page 17Linked to original sources
PubMed2005

Effect on enamel microhardness of two consumer-available bleaching solutions when compared with a dentist-prescribed, home-applied bleaching solution and a control.

BACKGROUND: There exists limited data in the literature regarding the efficacy and safety of consumer-available, paint-on bleaching solutions. PURPOSE: The purpose of this in vitro study was to evaluate the effect of two consumer-available, paint-on bleaching products on enamel microhardness against a control and a dentist-prescribed, home-applied (DPHA) bleaching product. MATERIALS AND METHODS: Eighty enamel slabs were obtained from extracted human teeth and randomly divided into four treatment groups: (1) control; (2) Opalescence (Ultradent Products, Inc., South Jordan, UT, USA); (3) Crest Night Effects (Procter & Gamble, Cincinnati, OH, USA); and (4) Colgate Simply White Night (Colgate-Palmolive Co., Piscataway, NJ, USA). Opalescence is a carbamide peroxide DPHA product, whereas Crest Night Effects and Colgate Simply White Night are consumer-available products. The specimens in groups 2 to 4 underwent 2 weeks of treatment for 8 h/d. Specimens were maintained in artificial saliva at 37 degrees C between treatments. Subsequently, one-half of the specimens in groups 2 to 4 (n=10) underwent an additional seven treatments for 8 h/d, while the other half were stored in artificial saliva, receiving no further treatment. Microhardness was measured as Knoop hardness numbers (KHNs) at baseline and after 1, 7, 14, and 21 treatment days. The results were analyzed for statistical significance both intra- and intergroups using analysis of variance (p=.05). RESULTS: A statistically significant reduction in mean KHN was observed compared with baseline at 1, 7, 14, and 21 treatment days for group 4 and at 7 treatment days for group 3. When compared with the control or DPHA product, group 4 was the only treatment that resulted in significantly lower mean KHNs at 7, 14, and 21 treatment days. CONCLUSION: When evaluating enamel microhardness, consumer available, paint-on bleaching solutions may adversely affect enamel microhardness compared to a control and 10% carbamide peroxide DPHA bleaching solution. CLINICAL SIGNIFICANCE: With numerous consumer-available bleaching products on the market, it is crucial to be judicious in their selection and use. The results of this in vitro study showed that the consumer-available, paint-on bleaching solutions adversely affected enamel microhardness at some time during the study. Consumers should be made aware of this effect on enamel.

Carbamide Peroxide↗
PubMed1981

Bulk solute extrusion as a mechanism conferring solute uptake specificity by pinocytosis in Amoeba proteus.

A variety of positively charged solutes induce pinocytosis in Amoeba proteus, ranging from metabolically useful material to solutes that may prove harmful, such as Alcian blue. Alcian blue is taken up by pinocytosis and then a fraction of the accumulated dye is expelled in bulk form through "extrusion channels." This response is not elicited by other solutes taken up by pinocytosis in the amoeba, implying that if any selectivity is associated with this process, it is by specific solute extrusion mechanisms in the cytoplasm.

Alcian Blue↗
PubMed1983

A standard aminophylline intravenous solution with flow rate label adapted to a manufacturer's standard solution.

The development of a standard aminophylline intravenous solution system utilizing a flow rate label is described. The original system was developed using 500 mg aminophylline in 250 ml of 5% dextrose injection in a polyvinyl chloride bag (PVC). An ancillary label was developed to be affixed to the bag to assist in maintaining flow rates. Later, this system was adapted to a premixed solution prepared by Travenol Laboratories. The difference, though, was the fact that a solution of 400 mg theophylline (equivalent to 500 mg of aminophylline) in 250 ml of 5% dextrose solution (PVC) was used. Hence, a new auxiliary label indicating flow rates between aminophylline and theophylline was developed. The success of both systems gave us more advantages than disadvantages. This was especially true with the premixed system. We feel that the auxiliary flow rate label helped maintain rates whether the physicians orders were written in theophylline or aminophylline. With proper nursing inservice, this standard aminophylline program could be successful using this auxiliary flow rate label.

Aminophylline↗
PubMed1990

Renal stones. Solutions and solute.

In the formation of calculi within the urinary tract, two fundamental factors are critical when crystals precipitate and stones form: They are solute and the solution itself, which must be oversaturated if crystals are to form and to grow. Several elements present in the urine influence solutions and solute and, thus, stone formation. Because all forms of medical therapy influence these elements favorably to prevent stone formation, this update reviews why stones form and how specific medical therapy works to prevent their formation.

Calcium Oxalate↗
PubMed1989

A comparative study of glycine fortified oral rehydration solution with standard WHO oral rehydration solution.

The safety, efficacy and acceptability of glycine-fortified oral rehydration solution (ORS) was compared with that of standard WHO-ORS in a controlled randomized trial. Fifty male infants with acute, watery, non-cholera diarrhea were studied. Glycine-fortified ORS at a concentration of 111 mmol/L (8.4 g/L) was used. The electrolyte and glucose concentrations of both the solutions was identical. The proportion of successfully treated patients was 92%. There were two failures in each group. Both solutions were found to be equally safe in correcting and maintaining the hydration status and in correcting hyponatremia and hypokalemia. The acceptability and efficiency of the solutions were also comparable. Addition of glycine does not add to the efficacy of conventional WHO-ORS, therefore offering no additional advantage but adds to the cost of production.

Administration, Oral↗
PubMed1978

[Aqueous iodine solutions as disinfectants: composition, stability, comparison with chlorine and bromine solution (author's transl)].

The equilibrium concentrations of aqueous iodine solutions in dependence of the total concentration and the pH-value have been calculated with and without regard of the iodate formation. The values obtained by the latter methode enabled by application of the known rate law to calculate the initial rate of the iodate formation and to draw from this conclusions concerning the stability of iodine solutions. On the grounds of these calculations to aqueous iodine solutions in the concentration and pH-range which is relevant for disinfection (greater than 10(-5) M/l, pH 6--9) one can attribute a stability sufficient for the use in practice and - unlike chlorine and bromine solutions - a content of bactericidal "free halogene" which is higher and independent of the pH-value. The disinfecting action of the iodine cation (H2O+J) which is supposed to be very powerful can be neglected because of its low concentration (10(-3)--10(-6%) of the total concentration). Hypoiodic acid which has already been converted into iodate by disproportionation is as good as lost for the disinfection because of the extremely slow reverse reaction.

Bromine↗
PubMed1978

Intraocular irrigating solutions. A comparative study of BSS Plus and lactated Ringer's solution.

Isolated human corneas maintained normal corneal thickness and endothelial ultrastructural integrity throughout a three-to four-hour period of perfusion of BSS plus to the endothelial surface. By comparison, only one of six human corneas perfused with lactated Ringer's solution was able to maintain normal thickness and ultrastructural integrity. The other five corneas perfused with lactated Ringer's solution showed various degrees of endothelial cell breakdown and corneal swelling during three hours of perfusion. The results of these studies suggest that BSS plus is a better solution for maintenance of human corneal endothelium during long-term (one- to three-hour) surgical procedures.

Cornea↗
PubMed1994

Comparison of histidine-tryptophan-ketoglutarate (HTK) solution versus University of Wisconsin (UW) solution for organ preservation in human liver transplantation. A prospective, randomized study.

Over a 30-month period, 60 patients (30 in each group) suffering from end-stage liver disease or primary hepatic malignancy and scheduled for liver transplantation were enrolled in a prospective, randomized study to compare two methods of liver preservation: histidine-tryptophan-ketoglutarate (HTK) solution versus University of Wisconsin (UW) solution. Entry criteria for both groups were: age (18-65 years), elective surgery (transplantable or urgent category of the recipients), first transplantations and harvesting procedure performed by the same team. The parameters under investigation were the clinical and laboratory data pre- and post-transplantation, as well as follow-up data such as complications and survival. There were no significant differences in the two groups as far as the evaluation criteria were concerned, even when cold ischemia time was more than 15 h (n = 7). A slight, yet not significant, increase in late complications of the biliary anastomoses could be seen in the UW group. Hepatocellular injury (SGOT, SGPT, GLDH, lactate) appeared to be more marked in the HTK group. These results suggest that both HTK and UW solutions are appropriate for clinical use in liver transplantation, even if cold ischemia time is more than 15 h.

Adenosine↗
PubMed1999

Transalveolar fluid absorption ability in rat lungs preserved with Euro-Collins solution and EP4 solution.

BACKGROUND: Pulmonary reimplantation response, presenting lung edema, is a major obstacle of lung transplantation. Transalveolar fluid absorption mechanism, regulated by active transalveolar Na+ transport via Na+ channel and Na+-K+-ATPase, is considered to be essential for resolution of lung edema. We investigated the effect of lung preservation on this fluid transport mechanism. METHODS: The rat lungs were flushed and preserved with either EP4 solution (EP4) or Euro-Collins solution (EC). First, we determined the basal transalveolar fluid movement by calculating alveolar fluid clearance (AFC) after pulmonary flushing, 24- and 72-hr preservation. Then, we assessed the effects of Na+ channel blocker, amiloride, and Na+-K+-ATPase inhibitor, ouabain, on AFC after 24-hr preservation. We further measured lung ATP content and Na+-K+-ATPase activity after 24-hr preservation to evaluate cellular metabolism and enzymatic activity during preservation. RESULTS: We found that the lungs preserved with EC showed significantly lower AFC and less inhibitory effects of both blockers than with EP4 after 24-hr preservation. Na+-K+-ATPase activity was significantly lower with EC than with EP4, even though lung ATP content was not affected by preservation solution. CONCLUSIONS: EP4 preservation provides a better environment for maintaining transalveolar fluid absorption mechanism than EC preservation. Therefore, lung preservation with EP4 may ensure more reliable ability in resolving pulmonary edema.

Adenosine Triphosphate↗
PubMed1991

Intraocular irrigating solutions: a clinical study of BSS plus and dextrose bicarbonate lactated Ringer's solution.

Intraocular irrigating solutions of varying compositions and costs are available for cataract surgery. We studied preoperative and two months postoperative extracapsular cataract extraction and intraocular lens implant corneal endothelial cell size in two groups. One group had received an intraoperative irrigating solution of lactated Ringer's with dextrose and bicarbonate. The other irrigating solution was BSS Plus which differs chiefly in the presence of glutathione. A nonstatistically significant trend in favor of BSS Plus was observed.

Acetates↗
PubMed1988

Quantitative assessment of postsurgical breakdown of the blood-aqueous barrier following administration of 0.5% ketorolac tromethamine solution. A double-masked, paired comparison with vehicle-placebo solution study.

Preoperative and serial postoperative anterior chamber fluorophotometry were performed after oral administration of fluorescein sodium in patients undergoing extracapsular cataract extraction and posterior chamber intraocular lens insertion. The administration of topical 0.5% ketorolac tromethamine solution before and after surgery markedly decreased the breakdown of the blood-aqueous barrier compared with vehicle-placebo solution administration at each time period, as measured by fluorophotometry. Corticosteroids were not given to any patients throughout the duration of the study. These fluorophotometric results correlated well with slit-lamp observations of postoperative ocular inflammation. Both ketorolac and vehicle were well tolerated by patients. No effects on intraocular pressure were seen with ketorolac administration. This study suggests that ketorolac ophthalmic solution is effective and safe as a nonsteroidal anti-inflammatory agent for topical use following cataract surgery and intraocular lens implantation.

Adult↗
PubMed1999

Capillary electrophoresis of small solutes in linear polymer solutions: relation between ionic mobility, diffusion coefficient and viscosity.

Electrophoretic mobilities, mu, and diffusion coefficients, D, of a small ion (molecular weight 579) were determined in dependence on the viscosity, eta, of aqueous buffer solutions containing ethylene glycol, or polyethylene glycol (PEG) with average molecular weights of 400, 20000, 100000 or 2000000, respectively, as additives. The values for mu and D are inversely proportional to the viscosity for the solutions with small-sized additives (ethylene glycol and PEG400), in accordance to Walden's rule. In contrast, for the longest polymers the mobilities and the diffusion coefficients approximate the values observed for pure water, and are nearly independent of the viscosity. This result agrees with the model of fractional free volume and the obstruction theory. For solutions with equal viscosity, three ranges can be differentiated for mu and D in relation to the size of the additive: for small additives, on the one hand, and the long-chained polymers, on the other hand, the values for mu and D are nearly independent of the size of the additive. In contrast, a pronounced increase of mu and D is found with increasing polymer size in the molecular weight range between 20000 and 100000. The ratio mu/D, occurring in a number of expressions for the plate height contributions, exhibits a remarkably small change over the entire polymer size and viscosity range (between 1 and 7 cP) under consideration. Consequently, the separation efficiency, expressed by the plate number, is found to be nearly constant, and is independent of viscosity.

Diffusion↗
PubMed2005

Effects of excluded volume and polydispersity on solution properties of lentinan in 0.1 M NaOH solution.

Seven lentinan fractions of various weight-average molecular weights (M(w)), ranging from 1.45 x 10(5) to 1.13 x 10(6) g mol(-1) were investigated by static light scattering and viscometry in 0.1M NaOH solution at 25 degrees C. The intrinsic viscosity [eta] - M(w) and radius of gyration s(2)(z) (1/2) - M(w) relationships for lentinan in 0.1M NaOH solution were found to be represented by [eta] = 5.1 x 10(-3)M(w) (0.81) cm(3) g(-1) and s(2)(z) (1/2) = 2.3 x 10(-1)M(w) (0.58) nm, respectively. Focusing on the effects of the M(w) polydispersity with the Schulz-Zimm distribution function, the data of M(w), s(2)(z) (1/2), and [eta] was analyzed on the basis of the Yoshizaki-Nitta-Yamakawa theory for the unperturbed helical wormlike chain combined with the quasi-two-parameter (QTP) theory for excluded-volume effects. The persistence length, molecular weight per unit contour length, and the excluded-volume strength were determined roughly to be 6.2 nm, 980 nm(-1), and 0.1, respectively. Compared with the theoretical value calculated by the Monte Carlo model, the persistence length is longer than that of the single (1 --> 3)-beta-(D)-glucan chain. The results revealed that lentinan exists as single-stranded flexible chains in 0.1M NaOH solution with a certain degree of expansion due to the electrostatic repulsion from the interaction between the OH(-) anions and lentinan molecules.

Carbohydrate Conformation↗
PubMed1987

Thermochemical investigations of associated solutions: 5. Calculation of solute-solvent equilibrium constants from solubility in mixtures containing two complexing solvents.

Solubilities are reported for carbazole in binary dibutyl ether plus 1-chlorohexane mixtures at 25 degrees C. Results of these measurements are compared with solution models developed for solubility in systems containing specific solute-solvent interactions. A simple stoichiometric complexation model based on a 1:1 carbazole:dibutyl ether complex could describe the measured solubility to within an average absolute deviation of 1.7%. The calculated equilibrium constant, though, was about one-half of values previously determined from carbazole solubilities in several binary dibutyl ether plus alkane mixtures. A more sophisticated solution model, derived by assuming both 1:1 carbazole: dibutyl ether and carbazole:chlorohexane complexes, could describe the solubilities to within 2.4%. This latter model enables the carbazole-chlorohexane association constant to be calculated from experimental carbazole solubilities and a priori knowledge of the carbazole-dibutyl ether equilibrium constant.

Carbazoles↗
PubMed1994

1H nuclear magnetic resonance studies of hen lysozyme-N-acetylglucosamine oligosaccharide complexes in solution. Application of chemical shifts for the comparison of conformational changes in solution and in the crystal.

Two-dimensional 1H nuclear magnetic resonance spectroscopy has been used to examine the complexes formed in solution between hen egg-white lysozyme and N-acetylglucosamine (GlcNAc) oligosaccharides. Changes in chemical shift have been measured for resonances of the majority of residues of lysozyme on binding the monomer, dimer and trimer of GlcNAc. The three inhibitors induce very similar changes in chemical shift, and these increase slightly with the length of the oligosaccharide. The largest changes are confined principally to the vicinity of site C in the active site cleft of the enzyme. These changes in chemical shift have been compared with differences in the ring current chemical shifts calculated from the crystal structures of unbound and GlcNAc3 bound lysozyme. This comparison suggests that the major conformational changes of residues in the vicinity of site C of the enzyme, that are caused by the binding of GlcNAc3, observed in the diffraction studies are at least consistent with the changes that occur in solution. Small changes in chemical shift are observed in the enzyme in regions remote from the active site, which indicate that the effects of inhibitor binding are felt throughout the enzyme. These changes in chemical shift correlate to a lesser extent than those near site C with the changes in chemical shift predicted from changes in conformation observed in the crystal structures. The results illustrate that chemical shifts are useful in assessing the significance of small conformational changes in proteins, although the usefulness of this approach will be limited by the resolution of the crystallographic structures, as well as the uncertainties in the origins of the chemical shift. Although conformational changes in site C account for many of the changes in the NMR spectrum of lysozyme, evidence is, however, presented for multiple binding sites for the GlcNAc oligosaccharides in solution, perhaps involving partial occupancy of site D.

Acetylglucosamine↗
PubMed1987

Enzyme action in polymer and salt solutions. I. Stability of penicillin acylase in poly(ethylene glycol) and potassium phosphate solutions in relation to water activity.

The stability of penicillin acylase (penicillin aminohydrolase, EC 3.5.1.11) was studied in poly(ethylene glycol) and potassium phosphate solutions. Enzyme stability measured as the half-life of the enzymatic activity and the transition temperature determined by differential scanning calorimetry, correlated well. The enzyme stability could not be related to the water activity as a measure of solute-solvent interaction. It seems to be related more to the concentration of the solutes and much less to the molecular weight of poly(ethylene glycol). The stabilizing effect of poly(ethylene glycol) is also discussed in terms of poly(ethylene glycol)-protein interactions.

Amidohydrolases↗
PubMed2006

A molecular-thermodynamic model for the interactions between globular proteins in aqueous solutions: applications to bovine serum albumin (BSA), lysozyme, alpha-chymotrypsin, and immuno-gamma-globulins (IgG) solutions.

To investigate globular protein-protein and protein-salt interactions in electrolyte solutions, a potential of mean force including hard-core repulsion, van der Waals attraction and electric double layer repulsion is proposed in this work. Both van der Waals attraction and double-layer repulsion are represented using hard spheres with two-Yukawa tails. The explicit analytical solution of osmotic pressure is derived from the first-order mean spherical approximation. From the comparison between the calculated and experimental values of osmotic pressures for aqueous bovine serum albumin (BSA), lysozyme, alpha-chymotrypsin, and immuno-gamma-globulins (IgG) solutions, we found that the proposed model is adequate for the description of the interactions between proteins at low ionic strength and small self-association of protein molecules. At high ionic strength, the charge inversions of protein molecules should be taken into account.

Binding Sites↗
PubMed2005

Aqueous penetration and biological activity of moxifloxacin 0.5% ophthalmic solution and gatifloxacin 0.3% solution in cataract surgery patients.

PURPOSE: To measure the achievable perioperative aqueous concentration of the commercially available topically administered fourth generation fluoroquinolones, moxifloxacin 0.5% ophthalmic solution, and gatifloxacin 0.3% ophthalmic solution, and to correlate this concentration with the agents' biological efficacy in the aqueous humor of patients undergoing routine cataract surgery. DESIGN: Prospective, randomized, parallel, double-masked, clinical trial. PARTICIPANTS: Fifty patients undergoing cataract extraction. METHODS: Patients (n = 25) were given perioperative topical moxifloxacin 0.5% or topical gatifloxacin 0.3% (n = 25). One drop of antibiotic was administered every 10 minutes for 4 doses beginning 1 hour prior to surgery. Aqueous humor was sampled via paracentesis and antibiotic concentrations were determined using validated high performance liquid chromatography (HPLC) procedures. Dilution analyses were performed to determine the biological efficacy of the agents in the aqueous against Staphylococcus epidermidis, the most common cause of postcataract endophthalmitis. MAIN OUTCOME MEASURES: Aqueous humor antibiotic concentrations were measured using HPLC and microdilution bioassay techniques. Biological activity was measured as minimal inhibitory dilution and minimal bactericidal dilution. RESULTS: Aqueous humor concentrations for moxifloxacin via HPLC analysis were 1.80 (+/-1.21) microg/ml, whereas those for gatifloxacin were 0.48 (+/-0.34) microg/ml. This 3.8-fold difference in aqueous humor antibiotic concentrations was statistically significant (P = 0.00003). Similarly, the biological dilution analysis of the aqueous humor samples showed that moxifloxacin attained an estimated activity of 2.1 microg/ml, whereas the gatifloxacin activity was approximately 0.4 mug/ml, which represented a 4.9-fold difference. CONCLUSIONS: This study demonstrated that after topically administered perioperative antibiotics with cataract surgery, moxifloxacin 0.5% ophthalmic solution achieved a statistically significantly higher concentration in aqueous humor compared with gatifloxacin (P = 0.00003). Results from the broth dilution analysis showed that moxifloxacin 0.5% was biologically more active against S. epidermidis than gatifloxacin 0.3% in aqueous humor after topical application. There were no adverse events reported, and incision wounds healed quickly and as expected.

Administration, Topical↗