Temperature: the single most important factor for degradation of glucose fluids during storage.
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OBJECTIVE: Bioincompatible glucose degradation products (GDPs) develop during heat sterilization of peritoneal dialysis (PD) fluids. However, degradation may also take place during storage. Consequently, storage may add to the bioincompatibility caused by heat sterilization. The aim of the present study was to investigate how different factors such as the sterilization procedure, pH, glucose concentration, and temperature influence GDP production during storage. DESIGN: Degradation in glucose solutions was followed by pH and UV absorbance at 228 nm and 284 nm over 2 years of storage. Different sterilization times, storage temperatures, pH, and glucose concentrations were included in the study. Peritoneal dialysis fluids were also used in the experiment. Bioincompatibility was estimated through inhibition of cell growth in L-929 fibroblasts, and GDPs through UV absorption and liquid chromatography. RESULTS: The most important factor determining the rate of GDP production during storage was temperature. The GDPs created by heat sterilization promoted further degradation of glucose during subsequent storage. A pH of around 3.2 protected glucose from degradation during both heat sterilization and storage. At a storage temperature of 20 degrees C and a pH of 3.2, degradation was almost negligible. Heat sterilization produced considerable amounts of GDPs absorbing at 228 nm. During initial storage, these 228 nm-absorbing GDPs almost disappeared. After reaching a nadir, absorbance at 228 nm again started to increase. Contrary to this, absorbance at 284 nm [caused mainly by 5-hydroxymethyl-2-furaldehyde (5-HMF)] increased during the whole storage period. After 2 years at 40 degrees C, the concentrations of GDPs produced during storage were of the same magnitude as those caused by heat sterilization. Inhibition of cell growth of L-929 fibroblasts correlated well with the part of the absorbance at 228 nm not caused by 5-HMF in glucose solutions that were heat sterilized under a wide range of conditions. This part of 228 nm absorbance (denoted 228corr) was caused almost entirely by 3,4-dideoxyglucosone-3-ene (3,4-DGE). CONCLUSIONS: Temperature is the single most important factor for glucose degradation during storage. The concentrations of bioincompatible GDPs produced may, under improper conditions, be as high as those produced during sterilization. High concentrations of glucose and low pH protect glucose from being degraded during both sterilization and storage. A good estimate of 3,4-DGE concentration in the fluids can be obtained correcting the UV absorbance at 228 nm for the influence from 5-HMF (and, when appropriate, for lactate). The 228corr may thus be used as a simple quality control for the fluids. (+info)
PD fluids contain high concentrations of cytotoxic GDPs directly after sterilization.
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OBJECTIVE: Glucose degradation products (GDPs) in peritoneal dialysis (PD) fluids are cytotoxic and affect the survival of the peritoneal membrane. One of the most reactive GDPs in PD fluids is 3,4-dideoxyglucosone-3-ene (3,4-DGE). 3,4-DGE has been reported as an intermediate between 3-deoxyglucosone (3-DG) and 5-hydroxymethyl furaldehyde (5-HMF) during degradation of glucose. In PD fluids, 3,4-DGE exists in a temperature-dependent equilibrium with a pool of unidentified substances. The aim of this study was to explore this equilibrium and its temperature dependence during the first months of storage after the sterilization procedure. METHODS: GDPs and inhibition of cell growth (ICG) were measured directly after sterilization of the PD fluid and during storage at different temperatures for 60 days. The following GDPs were analyzed: 3-DG, 3,4-DGE, 5-HMF, formaldehyde, acetaldehyde, glyoxal, and methylglyoxal. RESULTS: Immediately after sterilization, the concentration of 3,4-DGE was 125 micromol/L. During the first weeks of storage, it decreased by about 80%. At the same time, the 3-DG concentration increased. None of the other GDPs were significantly affected. Cytotoxicity correlated well with the concentration of 3,4-DGE. When pure 3,4-DGE was substituted for the lost amount of 3,4-DGE after 30 days of storage, the initial ICG was almost completely regained. CONCLUSIONS: Heat sterilization of PD fluids promotes the formation of large quantities of 3,4-DGE, rendering the fluid highly cytotoxic. During storage, the main part of 3,4-DGE is reversibly converted in a temperature-dependent manner to a less cytotoxic pool, consisting mainly of 3-DG. Cytotoxicity seems to be dependent exclusively on 3,4-DGE. In order to avoid higher levels of 3,4-DGE concentrations, PD fluids should not be used too soon after sterilization and should not be stored at temperatures above room temperature. (+info)
Triple fortification of salt with microcapsules of iodine, iron, and vitamin A.
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BACKGROUND: In many developing countries, children are at high risk of goiter, vitamin A deficiency, and iron deficiency anemia. OBJECTIVE: We aimed to develop a stable, efficacious salt fortified with iodine, iron, and vitamin A. DESIGN: A novel spray-cooling technique was used with hydrogenated palm oil to package potassium iodate, micronized ferric pyrophosphate, and retinyl palmitate into microcapsules (mean particle size: 100 mum). We used the microcapsules to create triple-fortified salt (TFS) with 30 mug I, 2 mg Fe, and 60 mug vitamin A/g salt. After storage trials, we compared the efficacy of TFS with that of iodized salt in a 10-mo, randomized, double-blind trial in goitrous schoolchildren (n = 157) who had a high prevalence of vitamin A deficiency and iron deficiency anemia. RESULTS: After storage for 6 mo, losses of iodine and vitamin A from the TFS were approximately 12-15%, and color was stable. In the TFS group, mean hemoglobin increased by 15 g/L at 10 mo (P < 0.01), iron status indexes and body iron stores improved significantly (P < 0.05), and mean serum retinol, retinol-binding protein, and the ratio of retinol-binding protein to prealbumin increased significantly (P < 0.01). At 10 mo, prevalences of vitamin A deficiency and iron deficiency anemia were significantly lower in the TFS group than in the iodized salt group (P < 0.001). CONCLUSION: Newly developed microcapsules containing iodine, iron, and vitamin A are highly stable when added to local African salt. TFS was efficacious in reducing the prevalence of iron, iodine, and vitamin A deficiencies in school-age children. (+info)
Stability of drug additives in peritoneal dialysis solutions in a new container.
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OBJECTIVE: To evaluate the stability of gentamicin, tobramycin, netilmycin, vancomycin, cefazolin, unfractionated heparin, and low molecular weight heparin when added to four different peritoneal dialysis (PD) solutions [Extraneal (Baxter Healthcare, Castlebar, Ireland); Physioneal, Nutrineal, and Dianeal (Baxter Healthcare, Grosotto, Italy)] in new, non-PVC Clear-Flex containers. MEASUREMENTS: Gentamicin, tobramycin, netilmycin, vancomycin, cefazolin, unfractionated heparin, and low molecular weight heparin were injected into separate bags of PD solution. Samples were withdrawn at predefined sampling times and the concentration of each drug was analyzed using high-performance liquid chromatography (for gentamicin, tobramycin, vancomycin, and cefazolin), or bioassay (for netilmycin, gentamicin, and tobramycin in Nutrineal), or coagulation methods (heparins). RESULTS: Netilmycin, vancomycin, cefazolin, and heparin in Physioneal, Nutrineal, Extraneal, and Dianeal were stable for at least 24 hours at 25 degrees C and for an additional 4 hours at 37 degrees C. Gentamicin in Nutrineal, Extraneal, and Dianeal was stable for at least 24 hours at 25 degrees C and for an additional 4 hours at 37 degrees C; gentamicin in Physioneal was stable for less than 24 hours at 25 degrees C. Tobramycin in Nutrineal and Extraneal was stable for at least 24 hours at 25 degrees C and for an additional 4 hours at 37 degrees C; tobramycin in Physioneal and Dianeal was stable for less than 24 hours at 25 degrees C. (+info)
An odorant derivative as an antagonist for an olfactory receptor.
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Different odorants are recognized by different combinations of G protein-coupled olfactory receptors, and thereby, odor identity is determined by a combinatorial receptor code for each odorant. We recently demonstrated that odorants appeared to compete for receptor sites to act as an agonist or an antagonist. Therefore, in natural circumstances where we always perceive a mixture of various odorants, olfactory receptor antagonism between odorants may result in a receptor code for the mixture that cannot be predicted from the codes for its individual components. Here we show that stored isoeugenol has an antagonistic effect on a mouse olfactory receptor, mOR-EG. However, freshly purified isoeugenol did not have an inhibitory effect. Instead, an isoeugenol derivative produced during storage turned out to be a potent competitive antagonist of mOR-EG. Structural analysis revealed that this derivative is an oxidatively dimerized isoeugenol that naturally occurs by oxidative reaction. The current study indicates that as odorants age, they decompose or react with other odorants, which in turn affects responsiveness of an olfactory receptor(s). (+info)
Antimalarial drug use among caregivers in Ghana.
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BACKGROUND: Chloroquine remains the first line antimalarial drug in Ghana. However, the emergence of Plasmodium falciparum resistance to chloroquine is a major obstacle to the national control strategy of case management. This study provides information on some of the reasons underlying chloroquine treatment failure in the country. METHODOLOGY: Household surveys, using multi-stage sampling, were conducted in 2 sentinel districts, Wassa West and Kassena Nankana, established to monitor chloroquine resistance in the country. Five hundred caregivers were interviewed in each district to determine patterns of antimalarial drug use among caregivers of children under 10 years. Inventory on home-kept drugs was conducted. RESULTS: Two hundred and four households in the Wassa West district kept a cumulative total of 248 drugs, whereas 228 households in the Kassena Nankana district kept a cumulative total of 410 drugs. One hundred and ninety-nine (80.2%) of the drugs kept in the Wassa West district and 181 (44.2%) of drugs kept in the Kassena Nankana district were antimalarials. The most commonly kept antimalarial drug in homes was chloroquine (88% and 96% in the Wassa West and Kassena Nankana districts respectively). Reasons given for keeping antimalarials were mainly "leftover after previous treatment". Caregivers' descriptions of the amount of chloroquine given to family members suspected to have malaria within the 2-week period preceding the survey were mostly inappropriate in the 2 districts. However, the proportion of appropriateness of doses was significantly lower in the Wassa West district (11.1% vs 36.4%; p < 0.0001). CONCLUSIONS: The significantly higher proportion of inappropriateness of chloroquine use in the Wassa West district could be a factor influencing the lower sensitivity of Plasmodium falciparum to chloroquine in the district compared to the Kassena Nankana district. (+info)
Effect of plasma treatment on adhesion of self-curing repair resin to acrylic denture base.
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Plasma irradiation on surface of heat-cured acrylic resin prior to processing self-curing acrylic resin is likely to effectively increase the adhesive strength between these materials for short-term period. However, long-term reliability of adhesive strength between these materials has not been clarified yet. In the present study, these materials were stored in water for a long period (100 days), and the effect on their shear bond strength was investigated. Forty-four test specimens with flat bonding test surface were made with heat-cured acrylic resin. They were divided into four groups according to treatment procedures for bonding surface: plasma treatment, adhesive primer application, adhesive primer application after plasma treatment, and no treatment (for control). Self-curing acrylic resin was processed against all bonding surfaces. After storage in water for 100 days, shear bond strength values between heat-cured and self-cured acrylic resins were measured. Specimens in plasma treatment group exhibited higher shear bond strength value than those in control, although the difference was not significant. (+info)
Adhesive strength of paint-on resins to crown and bridge composites.
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This paper examined the adhesive strength of paint-on resin to crown and bridge composites after soaking in water and thermal-cycling. Three shades of paint-on resin were coated on three kinds of crown and bridge composite under four surface treatment conditions (a combination of sandblaster and pretreatment liquid). These specimens were soaked in water at 37 degrees C for 1 day, 1 month, and 1 year, and at 4 degrees C and 60 degrees C alternatively for 1-minute periods for 10,000 cycles by thermal-cycling machine. The adhesive strengths were obtained by shear test. There were no significant differences among the adhesive strengths of three shades of paint-on resin to three composites after storage (p > 0.05). The adhesive strengths to composites with sandblasting showed higher values than those without it (p < 0.01). (+info)