Comparison of Amsorb, sodalime, and Baralyme degradation of volatile anesthetics and formation of carbon monoxide and compound a in swine in vivo. (17/368)

BACKGROUND: Consequences of volatile anesthetic degradation by carbon dioxide absorbents that contain strong base include formation of compound A from sevoflurane, formation of carbon monoxide (CO) and CO toxicity from desflurane, enflurane and isoflurane, delayed inhalation induction, and increased anesthetic costs. Amsorb (Armstrong Ltd., Coleraine, Northern Ireland) is a new absorbent that does not contain strong base and does not form CO or compound A in vitro. This investigation compared Amsorb, Baralyme (Chemetron Medical Division, Allied Healthcare Products, St. Louis, MO), and sodalime effects on CO (from desflurane and isoflurane) and compound A formation, carboxyhemoglobin (COHb) concentrations, and anesthetic degradation in a clinically relevant porcine in vivo model. METHODS: Pigs were anesthetized with desflurane, isoflurane, or sevoflurane, using fresh or partially dehydrated Amsorb, Baralyme, and new and old formulations of sodalime. Anesthetic concentrations in the fresh (preabsorber), inspired (postabsorber), and end-tidal gas were measured, as were inspired CO and compound A concentrations and blood oxyhemoglobin and COHb concentrations. RESULTS: For desflurane and isoflurane, the order of inspired CO and COHb formation was dehydrated Baralyme >> soda-lime > Amsorb. For desflurane and Baralyme, peak CO was 9,700 +/- 5,100 parts per million (ppm), and the increase in COHb was 37 +/- 14%. CO and COHb increases were undetectable with Amsorb. Oxyhemoglobin desaturation occurred with desflurane and Baralyme but not Amsorb or sodalime. The gap between inspired and end-tidal desflurane and isoflurane did not differ between the various dehydrated absorbents. Neither fresh nor dehydrated Amsorb caused compound A formation from sevoflurane. In contrast, Baralyme and sodalime caused 20-40 ppm compound A. The gap between inspired and end-tidal sevoflurane did not differ between fresh absorbents, but was Amsorb < sodalime < Baralyme with dehydrated absorbents. CONCLUSION: Amsorb caused minimal if any CO formation, minimal compound A formation regardless of absorbent hydration, and the least amount of sevoflurane degradation. An absorbent like Amsorb, which does not contain strong base or cause anesthetic degradation and formation of toxic products, may have benefit with respect to patient safety, inhalation induction, and anesthetic consumption (cost).  (+info)

Relaxation modulus of denture base resin reinforced with woven glass fibers. (18/368)

This study examined the reinforcing effect of woven glass fibers on the relaxation modulus by three-point loading of denture base resin. Three sandwich-type flexure test specimens polymerized by heating were used, all 3 mm thick: glass fibers in compression (U type); glass fibers in the center (C type); and glass fibers in tension (L type). Unreinforced specimens (ACR) were produced as a control. The relaxation modulus after 8 sec from the start of stress (Er(8)) was calculated from stress relaxation curves. In the glassy state, the Er(8)s of the U and L types were greater than those of the ACR and C types. In the rubbery state (plateau region), the Er(8)s of the U and L types were greater than those of the ACR and C types. The woven glass fibers added to the U and L type specimens increased the relaxation modulus of PMMA near the oral temperature; moreover, they inhibited stress relaxation when the temperature increased.  (+info)

The development of potential screens based on shoot calcium and iron concentrations for the evaluation of tolerance in Egyptian genotypes of white lupin (Lupinus albus L.) to limed soils. (19/368)

European cultivars of white lupin (Lupinus albus L.) grow poorly in limed or calcareous soils. However, Egyptian genotypes are grown successfully in highly calcareous soil and show no stress symptoms. To examine their physiological responses to alkaline soil and develop potential screens for tolerance, three experiments were conducted in limed and non-limed (neutral pH) soil. Measurements included net CO2 uptake, and the partitioning of Fe2+ and Fe3+ and soluble and insoluble Ca in stem and leaf tissue. Intolerant plants showed clear symptoms of stress, whereas stress in the Egyptian genotypes and in L pilosus Murr. (a tolerant species) was less marked. Only the intolerant plants became chlorotic and this contributed to their reduced net CO2 uptake in the limed soil. In contrast, Egyptian genotypes and L pilosus showed no change in net CO2 uptake between the soils. The partitioning of Ca and Fe either resulted from the stress responses, or was itself a stress response. L pilosus and some Egyptian genotypes differed in soluble Ca concentrations compared with the intolerant cultivars, although no significant difference was apparent in the Ca partitioning of the Egyptian genotype Giza 1. In a limed soil, Giza 1 maintained its stem Fe3+ concentration at a level comparable with that of plants grown in non-limed soil, whereas stem [Fe3+] of an intolerant genotype increased. Gizal increased the percentage of plant Fe that was Fe2+ in its leaf tissue under these conditions; that of the intolerant genotype was reduced. The potential tolerance of the Egyptian genotypes through these mechanisms and the possibility of nutritional-based screens are discussed.  (+info)

Management of hyperphosphataemia of chronic kidney disease: lessons from the past and future directions. (20/368)

A historical look at research in hyperphosphataemia of chronic kidney disease over the last 40 years shows remarkable advances in our understanding of this abnormality and in the technology used to manage it. Phosphate binders, which have become a mainstay in the management of hyperphosphataemia, have evolved from the early use of aluminium gels to calcium salts, to novel, non-absorbed, aluminium-free, calcium-free agents such as sevelamer hydrochloride, and to magnesium-, iron-, and lanthanum-based compounds. With recent advances, clinical management of this complication of chronic renal disease is evolving from adequate care to optimal care, such that new standards in phosphorous management are being set, and various parameters of patient care are being integrated to optimize outcomes and minimize side effects. This paper provides a historical view of the clinical management of hyperphosphataemia, and looks to advances in treatment that are changing the course of renal bone disease management.  (+info)

Study of resin-bonded calcia investment: part 2. Effect of titanium content on the dimensional change of the investment. (21/368)

In the present study, titanium powder was chosen as an expanding agent of an experimentally prepared resin-bonded calcia investment. The effect of Ti content on the dimensional change was investigated. In addition, the effects of the heating rate and heating temperature on the dimensional change of the investment were investigated during setting and after heating. The expansion increased with Ti content and the highest expansion (1.57%+/-0.58) was obtained at 10 mass% Ti. The highest expansion was obtained at 900 degrees C for 30 min heating and was independent of the heating rate. These findings mean that the titanium powder in the calcia investment oxidized sufficiently at that heating condition. It was found that the developed resin-bonded calcia investment was able to compensate for casting shrinkage of pure titanium by adding some Ti powder to the investment.  (+info)

The speed of soil carbon throughput in an upland grassland is increased by liming. (22/368)

In situ (13)C pulse labelling was used to measure the temporal and spatial carbon flow through an upland grassland. The label was delivered as (13)C-CO(2) to vegetation in three replicate plots in each of two treatments: control and lime addition. Harvests occurred over a two month period and samples were taken along transects away from the label delivery area. The (13)C concentration of shoot, root, bulk soil, and soil-respired CO(2) was measured. There was no difference in the biomass and (13)C concentration of shoot and root material for the control and lime treatments meaning that the amount of (13)C-CO(2) assimilated by the vegetation and translocated below ground was the same in both treatments. The (13)C concentration of the bulk soil was lower in the lime treatment than in the control and, conversely, the (13)C concentration of the soil-respired CO(2) was higher in the lime. Unlike the difference in bulk soil (13)C concentration between treatments, the difference in the (13)C concentration of the soil-respired CO(2) was obvious only at the delivery site and primarily within 1 d after labelling. An observed increase in the abundance of mycorrhizal fungi in the lime treatment was a possible cause for this faster carbon throughput. The potential key role of mycorrhizas in the soil carbon cycle is discussed. The importance of a better understanding of soil processes, especially biological ones, in relation to the global carbon cycle and environmental change is highlighted.  (+info)

Orthopedic devices; classification for the resorbable calcium salt bone void filler device. Final rule. (23/368)

The Food and Drug Administration (FDA) is classifying the resorbable calcium salt bone void filler device intended to fill bony voids or gaps of the extremities, spine, and pelvis that are caused by trauma or surgery and are not intrinsic to the stability of the bony structure into class II (special controls). Elsewhere in this issue of the Federal Register, FDA is announcing the availability of a class II special controls guidance entitled "Class II Special Controls Guidance Document: Resorbable Calcium Salt Bone Void Filler Device; Guidance for Industry and FDA." This action is being undertaken based on new information submitted in a classification proposal from Wright Medical Technology under the Federal Food, Drug, and Cosmetic Act as amended by the Medical Device Amendments of 1976, the Safe Medical Devices Act of 1990, and the Food and Drug Administration Modernization Act of 1997.  (+info)

Abortion, changed paternity, and risk of preeclampsia in nulliparous women. (24/368)

A prior birth confers a strong protective effect against preeclampsia, whereas a prior abortion confers a weaker protective effect. Parous women who change partners in a subsequent pregnancy appear to lose the protective effect of a prior birth. This study (Calcium for Preeclampsia Prevention Trial, 1992-1995) examines whether nulliparous women with a prior abortion who change partners also lose the protective effect of the prior pregnancy. A cohort analysis was conducted among participants in this large clinical trial of calcium supplementation to prevent preeclampsia. Subjects were nulliparous, had one prior pregnancy or less, delivered after 20 weeks' gestation, and were interviewed at 5-21 weeks about prior pregnancies and paternity. Women without a history of abortion served as the reference group in logistic regression analyses. Women with a history of abortion who conceived again with the same partner had nearly half the risk of preeclampsia (adjusted odds ratio = 0.54, 95 percent confidence interval: 0.31, 0.97). In contrast, women with an abortion history who conceived with a new partner had the same risk of preeclampsia as women without a history of abortion (adjusted odds ratio = 1.03, 95 percent confidence interval: 0.72, 1.47). Thus, the protective effect of a prior abortion operated only among women who conceived again with the same partner. An immune-based etiologic mechanism is proposed, whereby prolonged exposure to fetal antigens from a previous pregnancy protects against preeclampsia in a subsequent pregnancy with the same father.  (+info)