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Query: UNIPROT:Q86TM3 (cage)
 29,987 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The determination of the fate of a compound following administration can be performed using the disposition method with 14C-labeled substances, which also allow the measurement of metabolism with CO2 as an expired end product. To substitute the laborious CO2-collection in washing bottles as carbonate a simple instrumentation was built for continuous 14CO2-measurement. The air from the metabolic cage is led in thin layer through a chamber fitted to a foot-monitor, the output of which is online for computation. The instrument is sensitive and calibration is easy.
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PMID:[A simple method for 14CO2 measurement in metabolic experiments]. 181 66

In bicarbonate/CO2 buffer, Mn(II) and Fe(II) catalyze the oxidation of amino acids by H2O2 and the dismutation of H2O2. As the Mn(II)/Fe(II) ratio is increased, the yield of carbonyl compounds per mole of leucine oxidized is essentially constant, but the ratio of alpha-ketoisocaproate to isovaleraldehyde formed increases, and the fraction of H2O2 converted to O2 increases. In the absence of Fe(II), the rate of Mn(II)-catalyzed leucine oxidation is directly proportional to the H2O2, Mn(II), and amino acid concentrations and is proportional to the square of the HCO3- concentration. The rate of Mn(II)-catalyzed O2 production in the presence of 50 mM alanine or leucine is about 4-fold the rate observed in the absence of amino acids and accounts for about half of the H2O2 consumed; the other half of the H2O2 is consumed in the oxidation of the amino acids. In contrast, O2 production is increased nearly 18-fold by the presence of alpha-methylalanine and accounts for about 90% of the H2O2 consumed. The data are consistent with the view that H2O2 decomposition is an inner sphere (cage-like) process catalyzed by a Mn coordination complex of the composition Mn(II), amino acid, (HCO3-)2. Oxidation of the amino acid in this complex most likely proceeds by a free radical mechanism involving hydrogen abstraction from the alpha-carbon as a critical step. The results demonstrate that at physiological concentrations of HCO3- and CO2, Mn(II) is able to facilitate Fenton-type reactions.
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PMID:Manganese(II) catalyzes the bicarbonate-dependent oxidation of amino acids by hydrogen peroxide and the amino acid-facilitated dismutation of hydrogen peroxide. 229 94

An experiment with a factorial arrangement of treatment (3 by 2 by 2 by 2) was conducted to determine the effect of ascorbic-acid supplementation (0, 100, and 200 ppm) on the performance of two commercial layer strains housed at a density of either 3 or 4 birds per cage and relative humidities (RH) of 40% or 60%. The hens were subjected to a continuous heat stress of 31.1 degrees C for the 3-mo experimental period. As a comparison with an unstressed control group, an additional group of hens was housed at 23.9 degrees C and 40% RH and was fed the diet without ascorbic-acid supplementation. Mortality was reduced by ascorbic-acid supplementation. Shell weight per unit surface area showed a small increase with the added ascorbic acid. Values (in Haugh units) were increased by ascorbic-acid supplementation at the 200 ppm level and by the lower relative humidity. The higher RH reduced egg production by 4.16% and changed feed efficiency from 2.29 to 2.45 g of feed intake per gram of egg mass. There were differences in blood pH, blood CO2, blood HCO3-, and blood and adrenal ascorbic-acid levels due to the housing temperature. The higher RH produced blood-chemistry changes that were typical of respiratory alkalosis, which has been shown to occur in layers at high temperatures. Higher cage density, on the other hand, showed no change in the HCO3 level; but blood pCO2 was increased while blood pH was decreased. These results demonstrate that ascorbic-acid supplementation can be effective in reducing laying-hen mortality due to environmental stress and has small influences on egg quality.
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PMID:Effect of environmental stress on the ascorbic acid requirement of laying hens. 236 69

One hundred forty pubertal Swiss-Webster female mice (Mus musculus) were assigned randomly to a purified diet modified to contain 1, 2, 3, 4, 5 and 6 ppm copper as copper carbonate (Diets 1 thru 6, respectively). Diet 7 was a commercial rodent laboratory diet containing 11 ppm copper. Following 60 days of prefeeding, the breeding regimen was initiated by introducing a proven breeder male into each cage of 10 females in the afternoon and removing them the next morning. The breeding regimen was conducted for 28 days and females were either sacrificed at 24 or 96 hours following detection of a vaginal plug. Body weight, hematocrit, heart weight, hemoglobin concentration, ova recovery rate and fertilization rate were recorded for each female. All morphologically normal embryos collected 24 hours after detection of the vaginal plug were cultured and development in vitro evaluated. Body weight, hemoglobin concentration and hematocrit were lower (P less than .05), and heart weight and percent body weight occupied by the heart (%BWOH) were higher (P less than .05) in mice fed Diet 1. Heart weight and %BWOH were not different among mice fed Diets 2 thru 6 (P greater than .05). Ova recovery rate and fertilization rate were significantly reduced in mice maintained on Diet 1. The incidence of in vitro blastocyst formation was lower in embryos collected from females fed Diets 1 and 3 (P less than .05). Blastocyst hatching in vitro was not observed in embryos from females maintained on Diet 1, and was greater in embryos from females fed Diets 4, 5, and 7 (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The influence of dietary copper on reproduction, growth and the cardiovascular system in Swiss-Webster female mice. 293 89

Preliminary experiments established that a 0.5-ml inoculum that is introduced directly into the stomach of mice was cleared rapidly into the small intestine. Bicarbonate buffer, but not skim milk, protected such an inoculum from stomach acid until at least 90% of it had entered the small intestine. Passage and survival of various Escherichia coli strains through the mouse gut were tested by introducing a buffered bacterial inoculum directly into the stomach, together with the following two intestinal tracers: Cr(51)Cl(3) and spores of a thermophilic Bacillus sp. Quantitative recovery of excreted bacteria was accomplished by collecting the feces overnight in a refrigerated cage pan. The data show that wild-type E. coli strains and E. coli K-12 are excreted rapidly (98 to 100% within 18 h) in the feces without overall multiplication or death. E. coli varkappa1776 and DP50supF, i.e., strains certified for recombinant DNA experiments underwent rapid death in vivo, such that their excretion in the feces was reduced to approximately 1.1 and 4.7% of the inoculum, respectively. The acidity of the stomach had little bactericidal effect on the E. coli K-12 strain tested, but significantly reduced the survival of more acidsensitive bacteria (Vibrio cholerae) under these conditions. Long-term implantation of E. coli strains into continuous-flow cultures of mouse cecal flora or into conventional mice was difficult to accomplish. In contrast, when the E. coli strain was first inoculated into sterile continuous-flow cultures or into germfree mice, which were subsequently associated with conventional mouse cecal flora, the E. coli strains persisted in a large proportion of the animals at levels resembling E. coli populations in conventional mice. Metabolic adaptation contributed only partially to the success of an E. coli inoculum that was introduced first. A mathematical model is described which explains this phenomenon on the basis of competition for adhesion sites in which an advantage accrues to the bacterium which occupies those sites first. The mathematical model predicts that two or more bacterial strains that compete in the gut for the same limiting nutrient can coexist, if the metabolically less efficient strains have specific adhesion sites available. The specific rate constant of E. coli growth in monoassociated gnotobiotic mice was 2.0 h(-1), whereas the excretion rate in conventional animals was -0.23 h(-1). Consequently, limitation of growth must be regarded as the primary mechanism controlling bacterial populations in the large intestine. The beginnings of a general hypothesis of the ecology of the large intestine are proposed, in which the effects of the competitive metabolic interactions described earlier are modified by the effects of bacterial association with the intestinal wall.
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PMID:Survival and implantation of Escherichia coli in the intestinal tract. 633 89

Modified segmented polyurethanes were examined for biostability and biocompatibility using an in vivo cage implant system for time intervals of 1, 2, 3, 5, and 10 weeks. Two types of materials were used: polyether polyurethanes and polycarbonate polyurethanes. Two unmodified polyether polyurethanes (PEUU A' and SPU-PRM), one PDMS endcapped polyether polyurethane (SPU-S), and two polycarbonate polyurethanes (SPU-PCU and SPU-C) were investigated in this study. Techniques used to characterize untreated materials were dynamic water contact angle, stress-strain analysis, and gel permeation chromatography. Cellular response was measured by exudate analysis and by macrophage and foreign body giant cell (FBGC) densities. Material characterization, postimplantation, was done by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) in order to quantify biodegradation and scanning electron microscopy (SEM) to qualitatively describe the cellular response and biodegradation. The exudate analysis showed that the acute and chronic inflammatory responses for all materials were similar. Lower FBGC densities and cell coverage on SPU-S were attributed to the hydrophobic surface provided by the PDMS endgroups. The polycarbonate polyurethanes did not show any significant differences in cell coverage or FBGC densities even though the macrophage densities were slightly lower compared to polyether polyurethanes. By 10 weeks, biodegradation in the case of PEUU A' and SPU-PRM was extensive as compared to SPU-S because the PDMS endcaps of SPU-S provided a shield against the oxygen radicals secreted by macrophages and FBGCs and lowered the rate of biodegradation. In the case of polycarbonate polyurethanes, the oxidative stability of the carbonate linkage lowered the rate of biodegradation tremendously as compared to the polyether polyurethanes (including SPU-S). The minor amount of biodegradation seen in polycarbonate polyurethanes at 10 weeks was attributed to hydrolysis of the carbonate linkage.
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PMID:In vivo biocompatibility and biostability of modified polyurethanes. 926 87

A number of novel phosphate binders based on mixed metal hydroxide structures incorporating Fe and Ca, or Fe and Mg (classified as CT, Crosfield test compounds), were compared with the established phosphate binders Mg(OH)2, Al(OH)3, CaCO3 and a commercial hydrotalcite (Al- and Mg-based) using a rat model. The changes in urine and soluble faecal phosphate were used to evaluate efficacy of phosphate binding. The binders were mixed into a standard rat maintenance food at a concentration of 1% (w/w). Four rats were used for each binder study group and fed over 7 days. Urine and faeces were collected (in a metabolic cage) over the last 24-h study period and the phosphate content measured. The urinary phosphate was significantly reduced (P < 0.001) with CTFeCa (72+/-44 microm), CTFeMg (13+/-4 microm), CT100 (26+/-11 microm), and Mg(OH)2 (65+/-53 microm), compared with control (766+/-188 microm), Al(OH)3 (1,256+/-279 microm), and CaCO3 (857+/-25 microm). The soluble phosphate content of the faeces was significantly reduced (P < 0.05) by up to 60 % with CTFeCa, CTFeMg and Mg(OH)2, and up to 40% with CT100 and Al(OH)3, compared with 30% in controls and 10% with CaCO3. The new mixed metal hydroxy-carbonate compounds based on FeCa or FeMg are effective phosphate binders in-vivo and warrant further testing in patients.
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PMID:The evaluation of novel mixed metal hydroxy-carbonates as phosphate binders: an in-vivo study in the rat. 1134 68

Biodegradation and biocompatibility of poly(ethylene carbonate) (PEC) was examined using an in vivo cage implant system. Exudate analysis showed that PEC and PEC degradation products were biocompatible and induced minimal inflammatory and wound healing responses. Adherent foreign body giant cells (FBGCs) caused pitting on the PEC surface, which led to extensive degradation over time. Data obtained from molecular weight and examination of film cross-sections in the scanning electron microscope (SEM) indicated that PEC underwent surface erosion with no change to the remaining bulk. Attenuated total reflectance infrared (ATR-FTIR) spectroscopy was used to characterize the chemical degradation. Superoxide anion released from inflammatory cells appeared to initiate an "unzipping" mechanism of degradation by deprotonation of PEC hydroxyl end groups. The resulting alkoxide ion participated in a concerted mechanism involving water and the carbonate carbonyl, leading to elimination of ethylene glycol. Carbonate ions decomposed further with release of carbon dioxide to regenerate alkoxide ion.
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PMID:In vivo biocompatibility and biodegradation of poly(ethylene carbonate). 1464 76

Several strategies have been used to increase the biostability of medical-grade polyurethanes while maintaining biocompatibility and mechanical properties. One approach is to chemically modify or replace the susceptible soft segment. Currently, poly(carbonate urethanes) (PCUs) are being evaluated as a replacement of poly(ether urethanes) (PEUs) in medical devices because of the increased oxidative stability of the polycarbonate soft segment. Preliminary in vivo and in vitro studies have reported improved biostability of PCUs over PEUs. Although several studies have reported evidence of in vitro degradation of these new polyurethanes, there has been no evidence of significant in vivo degradation that validates a degradation mechanism. In this study, the effect of soft segment chemistry on the phase morphology, mechanical properties, and in vivo response of commercial-grade PEU and PCU elastomers was examined. Results from dynamic mechanical testing and infrared spectroscopy suggested that the phase separation was better in PCU as compared with PEU. In addition, the higher modulus and reduced ultimate elongation of PCU was attributed to the reduced flexibility of the polycarbonate soft segment. Following material characterization, the in vivo biostability and biocompatibility of PEU and PCU were studied using a subcutaneous cage implant protocol. The results from the cage implant study and cell culture experiments indicated that monocytes adhere, differentiate, and fuse to form foreign body giant cells on both polyurethanes. It is now generally accepted that the reactive oxygen species released by these adherent macrophages and foreign body giant cells initiate PEU biodegradation. Attenuated total reflectance-Fourier transform infrared analysis of explanted samples provided evidence of chain scission and crosslinking in both polyurethanes. This indicated that the PCU was also susceptible to biodegradation by agents released from adherent cells. These results reinforce the need to evaluate and understand the biodegradation mechanisms of PCUs.
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PMID:Poly(carbonate urethane) and poly(ether urethane) biodegradation: in vivo studies. 1512 87

We report a carboxylate triangle consisting of three manganese(II) centres which is made from manganese(II) carbonate and pivalic acid. The magnetic exchange within the triangle is extremely weak, and antiferromagnetic. Several models have been used to fit the magnetic data, and the best fit uses two weak antiferromagnetic coupling constants of J(1)=-0.588 cm(-1) and J(2)=-0.855 cm(-1). Exchange interactions between the metal centres has been calculated using DFT adopting all the three possible Heisenberg models for a trinuclear system and the results are compared with experimental values. Spin density distribution is used to analyse the nature of the coupling between the metal centres. EPR spectroscopy has been used to explore the nature of the ground state. Recrystallisation of the trinuclear compound from MeCN gives a polymer, while oxidation in air leads to a known compound--an edge-sharing bitetrahedral (MnIII2MnII4) cage.
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PMID:Synthesis and studies of a trinuclear Mn(II) carboxylate complex. 1530 71


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