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PubMed1982

[Effect of graded protein supply at high-energy level on the fattening performance and the retention and utilization of feed energy, protein and amino acids by female fattening swine. 3. N retention and N and lysine metabolism determined by N balance and N analysis of the carcasses].

The slaughtering of female fattening pigs differently supplied with protein and lysine (nearly constant proportions) showed that a high supply (III) in comparison to the standard supply (II) did not bring about better results. The lower consumption of digestible crude protein and lysine (I) resulted in a prolonged fattening period, lower daily protein retention (by 23%) and a lower content in live weight growth (by 5%). The two feeding variants I and III are therefore ineconomical and not recommendable. There are significant positive correlations between N-retention calculated from 3 N-balance measurings in the first fattening period (up to the 44th fattening day) and N-deposit ascertained after the analysis at the carcasses at the beginning and at the end of fattening. By means of the calculated estimate functions (1) y = 4.724 + 0.5432x and (2) y = 7.850 + 0.4961x the level of the real protein deposition (y) in the total fattening period can be derived from the N-balance (x) both in g per animal and day (1) and in g per kg live weight growth (2). The four complexes of causes for the differences in N-retention according to N-balance and N-deposit according to carcass analysis: 1. high N-deposition in the first fattening period; 2. unascertainable N-losses 3. the difference between slaughtering and total body weight and 4. physiologically caused deviations in the N-storage of the living organism, are discussed. Protein and lysine utilisations are comparable with values from literature achieved under similar conditions. In the group supplied according to standard (II) it is 29.5 and 45.6% resp. or, related to the digested quota, 36.6 and 57.7% resp. Here the protein (10.1 kg) and lysine (1,640 g) assigned for a live weight growth of 80 kg (35-115 kg) in 100 fattening days were consumed, which means that 162 g lysine were needed for 1 kg deposited protein.

Abattoirs↗

PubMed1993

Low-level radium retention by the human body: a modification of the ICRP publication 20 retention equation.

Recently published rates of elimination of radium (in percentage of contemporary body content per year) demonstrated that human radium cases with low body contents lost radium more rapidly than predicted by the ICRP Publication 20 retention equation. In ICRP Publication 20, the apposition and resorption rate in compact bone is defined as 2.5% y-1, but in the derivation of the retention equation for radium a value of only 1.5% y-1 was used. In the present work, the retention equation was reevaluated by using the rate of 2.5% y-1. The revised equation was a good fit to the data for measured values of the body content of radium from environmental levels of radium in food and water. The equation also described the observed rate of loss of radium at long times after deposition for radium cases with low measured body burdens.

Body Burden↗

PubMed1975

The influence of proximal retention grooves on the retention and resistance of class II preparations for amalgams.

The addition of proximal retention grooves to various designs of the Class II cavity preparation considerably improves the retention and resistance characteristics of amalgam restorations. The incorporation of proximal grooves should reduce the necessity for gross outline form as a means of gaining adequate retention adn resistance in the Class II preparation.

Dental Amalgam↗

PubMed2002

Molecular modeling of quantitative structure retention relationship studies: retention behavior of polychlorinated dibenzofurans on gas chromatographic stationary phases of varying polarity by a novel molecular distance edge vector.

Chemical structures of polychlorinated dibenzodioxin (PCDD) congeners are described by a novel molecular distance edge vector (VMDE), developed in our laboratory, that consists of the modified molecular distance edge parameters based on the identical group as a pseudo-atom instead of a traditional atom. Quantitative structure retention relationships (QSRRs) between the new VMDE parameters and the gas chromatographic retention behavior of PCDDs are then generated by a multiple linear regression method for nonpolar, moderately polar, and polar stationary phases. All QSRR models with a high correlation (R > 0.99) are developed for nonpolar, moderately polar, and polar columns (DB-5, SP-2100, SE-54, and OV-1701). Cross validation with the leave-one-out procedure is performed, and satisfactory results are obtained with high correlation. The obtained results show that the new VMDE vector is adapted to characterize the chemical structure and model the retention behavior of PCDDs on various polar stationary phases.

Journal Article↗

PubMed2002

Quantitative structure retention relationship studies for predicting relative retention times of chlorinated phenols on gas chromatography.

A new method of quantitative structure-retention relationship (QSRR) studies was reported for predicting gas chromatography (GC) relative retention times (RRTs) of chlorinated phenols (CPs) using a DB-5 column. Chemical descriptors were calculated from the molecular structure of CPs and related to their gas chromatographic RRTs by using multiple linear regression analysis. The proposed model had a multiple square correlation coefficient R2 = 0.970, standard error SE = 0.0472, and significant level P = 0.0000. The QSRR model also reveals that the gas chromatographic relative retention times of CPs are associated with physicochemical property interactions with the stationary phase, and influenced by the number of chlorine and oxygen in the CP mOlecules.

Chlorine Compounds↗

PubMed2005

Vestibular influence on water maze retention: transient whole body rotations improve the accuracy of the cue-based retention strategy.

Spatial learning in the water maze is thought to rely both on distal cues and vestibular information [Aggleton JP, Vann SD, Oswald CJP, Good M. Identifying cortical inputs to the rat hippocampus that subserves allocentric spatial processes: a simple problem with a complex answer. Hippocampus 2000;10:466-74; Pearce JM. Animal learning and cognition: an introduction. UK: Psychology Press; 1997]. Experiment 1 demonstrates that while water maze retention relies primarily on cue-platform based associations, this strategy is not precise, as animals tend to focus at the side of the pool. In experiment 2, we demonstrate that vestibular rotation eliminates this inaccuracy. These experiments highlight the importance of both cue and vestibular information for accurate retention of the water maze.

Analysis of Variance↗

PubMed2005

High-cholesterol diets impair short-term retention of memory in alloxan-induced diabetic mice, but not acquisition of memory nor retention of memory in prediabetic mice.

Whether high-cholesterol diets (HCD) induce a high incidence of memory deficits in diabetes requires to be established; if so, whether they induce impairments of memory acquired in the pre-diabetic stage as well as in the diabetic stage also needs to be elucidated, and part of the related mechanisms involved in this dysfunction should be determined. The mice were grouped into: normal mice fed normal diets (NN), diabetic mice fed normal diets (DN), normal mice fed HCD (NH), and diabetic mice fed HCD (DH). Animals were subjected to Morris water maze testing: 1) Learning in the pre-diabetic stage and memory retrieval in the diabetic stage; 2) Learning and memory retrieval in the diabetic stage. Following water maze testing, biochemical parameters were estimated in the animals. The results showed that significant impairments of memory retrieval, acquired in the diabetic stage, were observed only in DH group, neither in DN nor NH group in a short term compared with NN group. Biochemical parameters including fasting blood glucose, lipid peroxidation productions and acetylcholinesterase activities in frontal cortex and hippocampus increased more rapidly in DH group than those in the rest. These results indicate that HCD impair the diabetic retention of memory, but neither the diabetic acquisition of memory nor the pre-diabetic retention of memory in diabetic mice in a short term. Controlled HCD may be a strategy to prevent the loss of memory in diabetic individuals after they have acquired new information.

Acetylcholinesterase↗

PubMed2001

Retention behaviour of peptides, quinolones, diuretics and peptide hormones in liquid chromatography. Influence of ionic strength and pH on chromatographic retention.

Peptides, quinolones, diuretics and peptide hormones are important substances of biomedical interest. In this work a model describing the effect of pH on retention in liquid chromatography (LC) is established and tested for these compounds using an octadecylsilica column. The suggested model uses the pH value measured in the hydro-organic mixture used as mobile phase instead of the pH value in water and takes into account the effect of the activity coefficients. The proposed equations permit the prediction of the pH optimum using a minimum number of measurements and also permit the determination of the acidity constants of the compounds considered in the medium used as mobile phase. Moreover, these equations can be combined with the previously derived equations, that relate the retention with the solvent composition of the mobile phase, to establish a general model that relates the elution behaviour of the solute with the significant mobile phase properties: composition, pH and ionic strength.

Chromatography, Liquid↗

PubMed1983

High-performance liquid chromatography of amino acids, peptides and proteins. XLVIII. Retention behaviour of tryptic peptides of human growth hormone isolated by reversed-phase high-performance liquid chromatography: a comparative study using different chromatographic conditions and predicted elution behaviour based on retention coefficients.

The retention behaviour of the tryptic peptides of human growth hormone under a variety of reversed-phase chromatographic conditions has been investigated. By using water-acetonitrile gradients containing phosphate, bicarbonate, trifluoroacetate, or heptanesulphonate buffers, the influence of these ionic modifiers on peptide selectivity with several different alkylsilicas has been examined. Comparisons of observed and predicted retention behaviours for the various tryptic peptides in the different chromatographic systems are described. Application of these systems to the isolation of deamidated forms of human growth hormone is presented.

Amino Acids↗

PubMed2000

Prediction of the retentions of polybrominated dibenzo-p-dioxins (PBDDs) by using the retentions of polychlorinated dibenzo-p-dioxins (PCDDs).

The retention equations In k' = A + B/T of 49 polychlorinated dibenzo-p-dioxins (PCDDs) and 4 polybrominated dibenzo-p-dioxins (PBDDs) in gas chromatography (GC) have been investigated to evaluate the properties of regression coefficients A and B. The quantitative relationships between A and B values of PCDDs and those of PBDDs are found. The regression equations derived have correlation coefficients greater than 0.997. The A, B values of any PBDD can be predicted by using the A, B values of the PCDD according to these relationships. Using these predicted A and B values, the retention times of all PBDDs can be predicted at any temperature program. It is very useful to identify the peak position of any PBDD because at present there are only a few standards of PBDDs available.

Bromine Compounds↗

PubMed2002

Retention of ionizable compounds on HPLC. 12. The properties of liquid chromatography buffers in acetonitrile-water mobile phases that influence HPLC retention.

The addition of acetonitrile to aqueous buffers to prepare RP HPLC mobile phases changes the buffer properties (pH and buffer capacity). This variation is studied for ace tate, phosphate, phthalate, citrate, and ammonia buffers in acetonitrile-water mixtures up to 60% in acetonitrile (v/v). Equations are proposed to relate pH and buffer capacity change of these buffers to the initial aqueous pH value and to the volume fraction of acetonitrile added. It is demonstrated that the pH change of the buffer depends not only on the initial aqueous pH of the buffer and on the percentage of acetonitrile added but also on the particular buffer used. The proposed equations allow an accurate prediction of this ionization for the studied buffers. Since the retention of acid/base compounds shows a strong dependence of their degree of ionization, the equations are used to predict the change in this ionization with addition of acetonitrile when the RP HPLC mobile phase is prepared. This prediction allows estimation of the retention of an acid/base compound in a particular acetonitrile-water buffered mobile phase.

Journal Article↗

PubMed2004

Conclusive evidence for a retention-retention pathway for the molybdenum-catalyzed asymmetric alkylation.

Enantiomerically enriched, deuterated branched carbonates (Z)-(S)-PhCH(O2COMe)-CH=CHD (1a), (Z)-(R)-PhCH(O2COMe)CH=CHD (2a), and linear carbonate (E)-(S)-PhCH=CHCHD(O2COMe) (12) were employed as probes in the Mo-catalyzed asymmetric allylic alkylation with sodium dimethyl malonate, catalyzed by ligand complex 10 derived from the mixed benzamide/picolinamide of (S,S)-trans-diaminocyclohexane and (norbornadiene)Mo(CO)4. X-ray crystallography, along with solution NMR structural analysis of the pi-allyl intermediate and competition experiments, conclusively established the reaction proceeded via a retention-retention pathway. This mechanism contrasts with that defined for Pd-catalyzed allylic alkylations, which proceed via an inversion-inversion pathway.

Journal Article↗

PubMed1977

Nitrogen retention in rats fed on diets enriched with arginine and glycine. 2. Effect of diethyl ether anaesthesia on N retention.

1. Adult rats were subjected to a brief period of diethyl ether anaesthesia and were given diets with 200 or 100 g casein/kg with or without arginine plus glycine supplementation in the post-anaesthesia period. Nitrogen retention was measured as well as liver protein content and liver and muscle transaminase activities (L-aspartate aminotransferase (GOT), (EC 2.6.1.1), and L-alanine aminotransferase (GPT)(EC 2.6.1.2). 2. Results demonstrated that anaesthesia-stressed rats consuming the high-protein diet with supplemental arginine and glycine retained twice as much N as did rats given the diet with 200 g casein/kg alone, for the first 5 d post-anaesthesia. 3. Anaesthesia-stressed animals consuming the diets with 100 g casein/kg with or without arginine plus glycine supplementation did not differ from each other in N retention. 4. Liver protein content increased after anaesthesia in rats given the high-protein diets; liver transaminase activity increased, whereas muscle transaminase activity decreased, in animals consuming the high protein diets. 5. Possible mechanisms to account for these results are discussed.

Alanine Transaminase↗

PubMed1995

trans-Golgi retention of a plasma membrane protein: mutations in the cytoplasmic domain of the asialoglycoprotein receptor subunit H1 result in trans-Golgi retention.

Unlike the wild-type asialoglycoprotein receptor subunit H1 which is transported to the cell surface, endocytosed and recycled, a mutant lacking residues 4-33 of the 40-amino acid cytoplasmic domain was found to be retained intracellularly upon expression in different cell lines. The mutant protein accumulated in the trans-Golgi, as judged from the acquisition of trans-Golgi-specific modifications of the protein and from the immunofluorescence staining pattern. It was localized to juxtanuclear, tubular structures that were also stained by antibodies against galactosyltransferase and gamma-adaptin. The results of further mutagenesis in the cytoplasmic domain indicated that the size rather than the specific sequence of the cytoplasmic domain determines whether H1 is retained in the trans-Golgi or transported to the cell surface. Truncation to less than 17 residues resulted in retention, and extension of a truncated tail by an unrelated sequence restored surface transport. The transmembrane segment of H1 was not sufficient for retention of a reporter molecule and it could be replaced by an artificial apolar sequence without affecting Golgi localization. The cytoplasmic domain thus appears to inhibit interaction(s) of the exoplasmic portion of H1 with trans-Golgi component(s) for example by steric hindrance or by changing the positioning of the protein in the membrane. This mechanism may also be functional in other proteins.

Amino Acid Sequence↗

PubMed1990

Liquid chromatographic retention behavior and separation of chlorophenols on a beta-cyclodextrin bonded-phase column, Part I. Monoaromatic chlorophenols: retention behavior.

The liquid chromatographic retention behavior of nineteen monoaromatic chlorophenols on a beta-cyclodextrin bonded-phase column is investigated with respect to mobile phase composition, pH, temperature, and ionic strength. The mechanistic aspects of retention of these compounds on the beta-cyclodextrin column are studied and compared to other reversed-phase columns. Most of the evidence suggests that the unique selectivity of this column is due to inclusion complex formation, which provides the physical basis for the resolution of positional isomers. Under certain chromatographic conditions, however, the more highly chlorinated congeners appear to be excluded from the cyclodextrin cavity; in such cases a normal-phase chromatographic mechanism is postulated, based on the interaction of the substrates with the secondary hydroxyls on the periphery of the cyclodextrin moieties.

Chlorophenols↗

PubMedDate not supplied

Retention technique #3. Research: future impact on image and retention.

The recruitment, retention, utilization, and image of nursing are critical issues facing nurses today. Critical care nursing research will assist us in dealing with these problems to prepare for a twenty-first century in which nursing is a valued profession. This author takes an optimistic view of the future and explains how she believes nursing research will help solve these recruitment and retention problems.

Critical Care↗

PubMed2003

Necropsy practice after the "organ retention scandal": requests, performance, and tissue retention.

AIMS: After the so called "organ retention scandal" in the UK this study set out to assess the impact on death certification and hospital (consent) necropsies, including the postmortem retention of tissues and organs. METHODS: Data were prospectively gathered over a one year period for all deaths occurring at the Royal Hallamshire Hospital, Sheffield, UK to determine the frequencies with which death certificates were completed and necropsies were requested. The seniority of the clinician undertaking these duties was recorded. Pathologists were asked to record the extent of every necropsy during the study period. The type and planned uses of tissues retained were recorded. RESULTS: Death certificates were issued for 88.5% of the 966 deaths for which clinicians completed proformas. Of these, 88.9% were issued by preregistration and senior house officers. Consent was sought for a necropsy in 6.2% of cases (usually by non-consultant staff) and was granted in 43.4% of these. The overall, medicolegal, and hospital necropsy rates were 13.4%, 9.9%, and 3.5%, respectively. Tissues were retained from 55.4% of necropsies for diagnostic purposes, although sampling does not appear to be systematic. CONCLUSIONS: Death certification and seeking consent for a necropsy are frequently delegated to junior clinical staff. This may explain the low standard of death certification reported by others and the low necropsy rate. The decline in the necropsy rate and the low rate of sampling for histological examination highlight the decline of the hospital necropsy and the lack of a systematic approach to tissue sampling.

Autopsy↗

PubMed1985

The effect of hepatic insulin influx on insulin retention: comparison of net flux and per cent extraction as indices of hepatic insulin retention.

We studied effects of changes in hepatic insulin influx on hepatic insulin retention. In order to compare insulin net flux (influx - efflux) with percentage (%) hepatic insulin extraction (net flux/influx X 100), as indices of hepatic insulin retention, we examined which index is better predicted by insulin influx to the liver. Electromagnetic hepatic blood flow measurements were made and blood was sampled from portal, hepatic and peripheral veins and femoral artery in anesthetized dogs. Insulin influx was perturbed by sequentially superimposed peripheral venous infusions of somatostatin, glucagon and insulin (which were subsequently discontinued one at a time). Although the somatostatin was biologically effective in inhibiting insulin and glucagon release we found no significant plasma flow changes on starting or stopping the infusion of somatostatin (800 ng X kg-1 X min-1). Net insulin flux was linearly related to influx (n = 56, r = 0.99, p less than 0.001). Hepatic glucose production was better correlated with net insulin flux (r = -0.66; p less than 0.01) than with % extraction (r = 0.08; N.S.), when mean glucagon influx was held constant (partial correlation). Although net insulin flux and % extraction are complementary indices, the former reflects influx changes more faithfully than the latter.

Animals↗