Showing papers by "Memorial University of Newfoundland published in 2000"
TL;DR: In this paper, the authors present an OPUS article with permission from SHERPA/RoMEO to retain article in OPUS, which they refer to as their work.
Abstract: Permission obtained via SHERPA/RoMEO. Letter from publisher grants permission to retain article in OPUS.
748 citations
TL;DR: In this article, the authors present a model of The Netherlands at 500 m resolution driven by a macro-scale dynamical spatial interaction model defined on 40 economic regions; this model is in turn driven by national planning projections and policy goals.
616 citations
TL;DR: Mixed tocopherols, herbal extracts such as those of rosemary and sage, as well as tea extracts have been commercialized for food and nutraceutical applications to address the demand by consumers.
Abstract: Antioxidants may be present in foods as endogenous factors or may be added to preserve their lipid components from quality deterioration. Synthetic antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PG) and tert-butylhydroquinone (TBHQ) are commonly used in food formulations. However, due to safety concerns, interest in natural antioxidants has intensified. To address the demand by consumers, mixed tocopherols, herbal extracts such as those of rosemary and sage, as well as tea extracts have been commercialized for food and nutraceutical applications. An overview of the topic is provided in this article.
568 citations
TL;DR: In this paper, the experimental partitioning of an extensive array of trace elements between rutile/melt pairs is presented which enables the effect of rutiles during melting in subduction zones to be directly assessed.
534 citations
TL;DR: The plasma concentrations of V LDL particles and apoCIII in VLDL and LDL are more specific measures of coronary heart disease risk than plasma triglycerides perhaps because their known metabolic properties link them more closely to atherosclerosis.
Abstract: Background—Plasma triglyceride concentration has been an inconsistent independent risk factor for coronary heart disease, perhaps because of the metabolic heterogeneity among VLDL particles, the main carriers of triglycerides in plasma. Methods and Results—We conducted a prospective, nested case-control study in the Cholesterol and Recurrent Events (CARE) trial, a randomized placebo-controlled trial of pravastatin in 4159 patients with myocardial infarction and average LDL concentrations at baseline (115 to 174 mg/dL, mean 139 mg/dL). Baseline concentrations of VLDL–apolipoprotein (apo) B (the VLDL particle concentration), VLDL lipids, and apoCIII and apoE in VLDL+LDL and in HDL were compared in patients who had either a myocardial infarction or coronary death (cases, n=418) with those in patients who did not have a cardiovascular event (control subjects, n=370) in 5 years of follow-up. VLDL-cholesterol, VLDL-triglyceride, VLDL-apoB, apoCIII and apoE in VLDL+LDL and apoE in HDL were all interrelated, and ...
481 citations
TL;DR: A general nonparametric mixture model that extends models and improves estimation methods proposed by other researchers and extends Cox's proportional hazards regression model by allowing a proportion of event-free patients and investigating covariate effects on that proportion.
Abstract: Nonparametric methods have attracted less attention than their parametric counterparts for cure rate analysis. In this paper, we study a general nonparametric mixture model. The proportional hazards assumption is employed in modeling the effect of covariates on the failure time of patients who are not cured. The EM algorithm, the marginal likelihood approach, and multiple imputations are employed to estimate parameters of interest in the model. This model extends models and improves estimation methods proposed by other researchers. It also extends Cox's proportional hazards regression model by allowing a proportion of event-free patients and investigating covariate effects on that proportion. The model and its estimation method are investigated by simulations. An application to breast cancer data, including comparisons with previous analyses using a parametric model and an existing nonparametric model by other researchers, confirms the conclusions from the parametric model but not those from the existing nonparametric model.
404 citations
TL;DR: Normalization of hemoglobin does not lead to regression of established concentric LV hypertrophy or LV dilation, and it may, however, prevent the development of LV dilated and it leads to improved quality of life.
394 citations
TL;DR: The effects of fishing on birds may be direct or indirect as discussed by the authors, although on a lesser scale some fishing activities also disturb birds, such as by-catch of albatrosses and petrels in longlines in the North Pacific and in the Southern Ocean.
Abstract: Birds are the most conspicuous, wide-ranging, and easily studied organisms in the marine environment. They can be both predators and scavengers, and they can be harmed by and can benefit from fishing activities. The effects of fishing on birds may be direct or indirect. Most direct effects involve killing by fishing gear, although on a lesser scale some fishing activities also disturb birds. Net fisheries and hook fisheries have both had serious negative effects at the population level. Currently, a major negative impact comes from the by-catch of albatrosses and petrels in long-lines in the North Pacific and in the Southern Ocean. High seas drift nets have had, prior to the banning of their use, a considerable impact on seabirds in the northern Pacific, as have gillnets in south-west Greenland, eastern Canada, and elsewhere. Indirect effects mostly work through the alteration in food supplies. Many activities increase the food supply by providing large quantities of discarded fish and wastes, particularly those from large, demersal species that are inaccessible to seabirds, from fishing vessels to scavengers. Also, fishing has changed the structure of marine communities. Fishing activities have led to depletion of some fish species fed upon by seabirds, but may also lead to an increase in small fish prey by reducing numbers of larger fish that may compete with birds. Both direct and indirect effects are likely to have operated at the global population level on some species. Proving the scale of fisheries effects can be difficult because of confounding and interacting combinations with other anthropogenic effects (pollution, hunting, disturbance) and oceanographic factors. Effects of aquaculture have not been included in the review. 2000 International Council for the Exploration of the Sea
327 citations
TL;DR: The results demonstrate that dietary consumption of B. lactis HN019 can enhance natural immunity in healthy elderly subjects, and that a relatively short-term dietary regime is sufficient to impart measurable improvements in immunity that may offer significant health benefits to consumers.
Abstract: Objective: To determine the effects of dietary consumption of Bifidobacterium lactis (strain HN019, DR10TM) on natural immunity. Design: A randomized, double blind, placebo-controlled clinical trial. Setting:: Janeway Medical Centre, Memorial University, St Johns, Newfoundland. Subjects: Twenty-five healthy elderly volunteers (median age 69 y; range 60–83 y). Interventions: Twelve control subjects consumed 180 ml low-fat/low-lactose milk twice daily for a period of 6 weeks; 13 test subjects consumed milk supplemented with 1.5×1011 colony-forming units of B. lactis twice daily. Indices of natural immunity, including interferon production, phagocytic capacity and phagocyte-mediated bactericidal activity, were determined via peripheral blood at 0, 3, 6 and 12 weeks post-trial commencement. Results: Subjects who consumed milk containing B. lactis for 6 weeks produced significantly enhanced levels of interferon-alpha, upon stimulation of their peripheral blood mononuclear cells in culture, in comparison to the placebo control group who received milk alone. There were also significant increases in polymorphonuclear cell phagocytic capacity among test group subjects, following consumption of milk supplemented with B. lactis, while individuals who consumed B. lactis-supplemented milk or milk alone showed enhanced phagocyte-mediated bactericidal activity. Conclusions: The results demonstrate that dietary consumption of B. lactis HN019 can enhance natural immunity in healthy elderly subjects, and that a relatively short-term dietary regime (6 weeks) is sufficient to impart measurable improvements in immunity that may offer significant health benefits to consumers. Sponsors: Financial support for this project was provided by the New Zealand Dairy Board. European Journal of Clinical Nutrition (2000) 54, 263–267
324 citations
TL;DR: The data suggest that a complete loss of function of the MKKS product, and thus an inability to fold a range of target proteins, is responsible for the clinical manifestations of BBS.
Abstract: Bardet-Biedl syndrome (BBS) is an autosomal recessive disorder predominantly characterized by obesity, retinal dystrophy, polydactyly, learning difficulties, hypogenitalism and renal malformations, with secondary features that include diabetes mellitus, endocrinological dysfunction and behavioural abnormalities. Despite an initial expectation of genetic homogeneity due to relative clinical uniformity, five BBS loci have been reported, with evidence for additional loci in the human genome; however, no genes for BBS have yet been identified. We performed a genome screen with BBS families from Newfoundland that were excluded from BBS1-5 and identified linkage with D20S189. Fine-mapping reduced the critical interval to 1.9 cM between D20S851 and D20S189, encompassing a chaperonin-like gene. Mutations in this gene were recently reported to be associated with McKusick-Kaufman syndrome (MKKS; ref. 8). Given both the mapping position and clinical similarities of these two syndromes, we screened MKKS and identified mutations in five Newfoundland and two European-American BBS pedigrees. Most are frameshift alleles that are likely to result in a non-functional protein. Our data suggest that a complete loss of function of the MKKS product, and thus an inability to fold a range of target proteins, is responsible for the clinical manifestations of BBS.
310 citations
TL;DR: In this paper, eight silicate glasses were prepared by directly fusing and stirring 50-100 g each of basalt, andesite, komatiite, peridotite, rhyolite, and quartz-diorite.
Abstract: Eight silicate glasses were prepared by directly fusing and stirring 50-100 g each of basalt, andesite, komatiite, peridotite, rhyolite, and quartz-diorite. These are referred to as MPI-DING glasses and were made for the purpose of providing reference materials for geochemical, in-situ microanalytical work. Results from various analytical techniques indicate that individual glass fragments are well homogenised with respect to major and trace elements at the μm to mm scale. Heterogeneities due to quench crystallisation of olivine have been observed in small and limited areas of the two komatiitic glasses. In order to obtain concentration values for as many elements as possible, the glasses were analysed by a variety of bulk and microanalytical methods in a number of laboratories. The analytical uncertainties of most elements are estimated to be between 1% and 10%. From the analytical data, preliminary reference values for more than sixty elements were calculated. The analytical uncertainties of most elements are estimated to be between 1% and 10%.
Huit verres silicates ont ete prepares directement par fusion et melange de 50 a 100 g de basalte, andesite, komatiite, peridotite, rhyolite et diorite quartzique. Ils sont references sous l'appellation verres MPI-DING et ont ete prepares pour fournir des materiaux de reference pour la micro-analyse geochimique in situ. Les resultats obtenus par differentes methodes analytiques montrent que des fragments de verre individuels sont bien homogeneises, tant au niveau des elements majeurs et en traces qu'au niveau du μm au mm. Des heterogeneites provenant de la cristallisation de l'olivine au cours de la trempe n'ont ete observees que dans quelques petites zones de deux verres komatiitiques. Afin d'obtenir des valeurs de concentrations pour le plus grand nombre d'elements, plusieurs laboratoires. A partir de ces donnees, des valeurs de reference preliminaires ont ete calculees pour plus de 60 elements. Les incertitudes analytiques de la plupart des elements sont estimees entre 1 et 10%.
08 Oct 2000
TL;DR: In this article, an adaptive backstepping technique for an interior permanent-magnet synchronous motor (IPMSM) drive based on newly developed adaptive back stepping technique is presented.
Abstract: This paper presents a novel speed control technique for an interior permanent-magnet synchronous motor (IPMSM) drive based on newly developed adaptive backstepping technique. The proposed stabilizing feedback law for the IPMSM drive is shown to be globally asymptotically stable in the context of Lyapunov theory. The adaptive backstepping technique takes system nonlinearities into account in the control system design stage. The detailed derivations of the control laws have been given for controller design. The complete IPMSM drive incorporating the proposed backstepping control technique has been successfully implemented in real-time using digital signal processor board DS1102 for a laboratory 1-hp motor. The performance of the proposed drive is investigated both in experiment and simulation at different operating conditions. It is found that the proposed control technique provides a good speed tracking performance for the IPMSM drive ensuring the global stability.
08 Oct 2000
TL;DR: In this paper, a fuzzy logic speed controller is employed in the outer loop of an IM drive for speed control of an induction motor using indirect vector control, and the performance of the proposed FLC based IM drive is compared to those obtained from the conventional proportional integral (PI) controller based drive both theoretically and experimentally at different dynamic operating conditions such as sudden change in command speed, step change in load, etc.
Abstract: This paper presents a novel speed control scheme of an induction motor (IM) using fuzzy logic control. The fuzzy logic controller (FLC) is based on the indirect vector control. The fuzzy logic speed controller is employed in the outer loop. The complete vector control scheme of the IM drive incorporating the FLC is experimentally implemented using a digital signal processor board DS-1102 for the laboratory 1 hp squirrel cage induction motor. The performances of the proposed FLC based IM drive are investigated and compared to those obtained from the conventional proportional integral (PI) controller based drive both theoretically and experimentally at different dynamic operating conditions such as sudden change in command speed, step change in load, etc. The comparative experimental results show that the FLC is more robust and hence found to be a suitable replacement of the conventional PI controller for the high performance industrial drive applications.
TL;DR: All indices except Fulton's condition factor, residualized water weight, and percent water were significantly correlated with fat weight for all combinations of combinations of fish sampled on a seasonal basis.
Abstract: We investigated the relationship between fat content and condition indices in Atlantic salmon Salmo salar parr sampled from a wild population on a seasonal basis. Condition of individual fish was indexed by residuals from the least-squares regressions of fat weight, dry weight, wet weight, and water weight (separately on fork length) as well as by relative condition factor, Fulton's condition factor, percent fat, and percent water. For all fish analyzed in the study (n = 284), residualized fat weight accounted for 81% of the variation in percent fat, for 58% of the variation in residualized dry weight, for 46% of the variation in residualized wet weight and relative condition factor, for 41% of the variation in Fulton's condition factor, for 35% of the variation in residualized water weight, and for 28% of the variation in percent water. All indices except Fulton's condition factor, residualized water weight, and percent water were significantly correlated with fat weight for all combinations of ...
TL;DR: An overview of the basic physiological and pharmacological tenets of blood vessels is given in this article, along with in vivo and in vitro methods used in the measurement of blood flow and blood vessel function.
TL;DR: 34 unrelated probands with classic features of BBS including retinitis pigmentosa, obesity and polydactyly are ascertained and MKKS mutations in four typical BBS probands are found.
Abstract: Bardet-Biedl syndrome (BBS) is an autosomal recessive disorder with locus heterogeneity5,6,7,8,9. None of the ‘responsible’ genes have previously been identified. Some BBS cases (approximately 10%) remain unassigned to the five previously mapped loci10. McKusick-Kaufma syndrome (MKS) includes hydrometrocolpos, postaxial polydactyly and congenital heart disease, and is also inherited in an autosomal recessive manner11,12. We ascertained 34 unrelated probands with classic features of BBS including retinitis pigmentosa (RP), obesity and polydactyly. The probands were from families unsuitable for linkage because of family size. We found MKKS mutations in four typical BBS probands (Table 1). The first is a 13-year-old Hispanic girl with severe RP, PAP, mental retardation and obesity (BMI >40). She was a compound heterozygote for a missense (1042G→A, G52D) and a nonsense (1679T→A, Y264stop) mutation in exon 3. Cloning and sequencing of the separate alleles confirmed that the mutations were present in trans. A second BBS proband (from Newfoundland), born to consanguineous parents, was homozygous for two deletions (1316delC and 1324-1326delGTA) in exon 3, predicting a frameshift. An affected brother was also homozygous for the deletions, whereas an unaffected sibling had two normal copies of MKKS. Both the proband and her affected brother had RP, PAP, mild mental retardation, morbid obesity (BMI >50 and 37, respectively), lobulated kidneys with prominent calyces and diabetes mellitus (diagnosed at ages 33 and 30, respectively). A deceased sister (DNA unavailable) had similar phenotypic features (RP with blindness by age 13, BMI >45, abnormal glucose tolerance test and IQ=64, vaginal atresia and syndactyly of both feet). Both parents and the maternal grandfather were heterozygous for the deletions. Genotyping with markers from the MKKS region12 confirmed homozygosity at 20p12 in both affected individuals.
TL;DR: A PC-based videoconferencing system was used to conduct child psychiatry assessments and the majority of children 82 liked' using the telepsychiatry system and six preferred it to a FTF assessment, but the responses from the psychiatrist satisfaction questionnaire showed that they preferred FTF assessments.
Abstract: We used a PC-based videoconferencing system to conduct child psychiatry assessments. The telecommunications link was six digital lines, giving a total bandwidth of 336 kbit s. Twenty-three patients aged 4-16 years, accompanied by their parents, completed two psychiatric assessments, one via videoconferencing and another face to face FTF. The order of assessments was randomized. Questionnaires were used to record the diagnosis, treatment recommendations and the psychiatrists', patients' and their parents' satisfaction with each assessment. An independent evaluator concluded that in 22 cases 96 the diagnosis and treatment recommendations made via the videoconferencing system were the same as those made FTF. The psychiatrists stated that videoconferencing assessments were an adequate alternative to FTF assessments and did not interfere with diagnosis. However, the responses from the psychiatrist satisfaction questionnaire showed that they preferred FTF assessments. No significant difference was found in the ...
Journal Article•
TL;DR: It is concluded that HPV testing in conjunction with cytology improved the screening efficacy of cytology alone and may allow for a more effective and safe primary screening program with increased screening intervals.
Abstract: Our objective was to determine whether the addition of human papillomavirus (HPV) testing to screening cytology improves the detection of cervical cancer precursors. Women of ages 18-69 years underwent conventional Pap cytology and HPV DNA testing in a multicenter study in Newfoundland, Canada. Those with positive cytology and/or HPV and a random sample of those with dual negative results were referred for colposcopy. The study enrolled 2098 women. The relative sensitivity of HPV testing was significantly higher than cytology for all-grade squamous intraepithelial lesions [SILs; 73%; 95% confidence interval (CI), 62-82] and high grade SILs (HSILs; 90%; 95% CI, 74-97) but had lower relative specificity (62% for all-grade SILs and 51% for HSILs) than most cytological cutpoints. The rate of combined correct results for all-grade lesions was higher for HPV testing (68.8%) than for any cytological cutpoint (equivocal, 52.3%; LSILs, 51.6%; HSILs, 44.5%). The combination of HPV and an LSIL cutpoint had a negative predictive value of 68% (95% CI, 52-80) for all SILs and 100% (95% CI, 91-100) for HSILs, while referring for colposcopy only 12% of the women. We concluded that HPV testing in conjunction with cytology improved the screening efficacy of cytology alone and may allow for a more effective and safe primary screening program with increased screening intervals.
TL;DR: This review demonstrates that chitin and chitosan oligomers can be prepared by chemical and enzymatic hydrolyses and that the oligomers with high degrees of polymerization, especially those with six residues or more, show strong physiological activities.
Abstract: Chitin and chitosan are known to possess multiple functional properties. Chitin is insoluble in any common solvent containing organic or mineral acid as well as water. Chitosan is water-insoluble and highly viscous in dilute acidic solutions. These solubility problems may restrict their use in physiological functional foods. However, chitin and chitosan oligomers are not only water-soluble and their solutions have low viscosity values, but they may also be absorbed in the human intestine. They may have much physiological functionality in the in vivo systems. This review demonstrates that chitin and chitosan oligomers can be prepared by chemical and enzymatic hydrolyses and that the oligomers with high degrees of polymerization, especially those with six residues or more, show strong physiological activities.
TL;DR: In this article, borage and evening primrose crude extracts and their fractions were obtained and their content of total, hydrophilic and hydrophobic phenolics determined using Sephadex LH-20 column chromatography.
TL;DR: In this paper, a review summarizes the current knowledge on acid hydrolysis of starches from different botanical origins, including changes in molar mass, crystallinity, viscosity, gel rigidity and gelatinization transition temperatures.
Abstract: Acids such as HCl and H2SO4 cause scission of the glucosidic linkages, thereby altering the structure and properties of the native starch. The amorphous regions of the starch granule are more susceptible to acid hydrolysis than the crystalline regions. This review summarizes the current knowledge on: (1) the extent of acid hydrolysis of starches from different botanical origins; (2) the changes in molar mass, crystallinity, viscosity, gel rigidity and gelatinization transition temperatures on acid hydrolysis; (3) the effect of annealing, heat–moisture treatment, high pressure, and amylose-complexed lipids on the rate and extent of acid hydrolysis and; (4) the mechanism of acid hydrolysis in an alcoholic media.
TL;DR: To evaluate women's sexual experience in pregnancy, and to describe their sources of information regarding sexuality during this period, a survey of women from around the world is conducted.
01 Jan 2000
TL;DR: In this article, the authors used sediment cores to assess the health of an ecosystem and the degree to which it has been influenced by terrestrial and anthropogenic inputs using biomarkers such as lipid classes and fatty acids to determine production of marine biogenic material.
Abstract: Biomarkers are compounds or groups of compounds that can be used as signatures of individual organisms or groups of organisms, or of certain environmental processes Lipid and phenolic biomarkers can be used to assess the health of an ecosystem and the degree to which it has been influenced by terrestrial and anthropogenic inputs Lipid classes and fatty acids can be used to determine production of marine biogenic material of dietary value to pelagic and benthic organisms Polycyclic aromatic hydrocarbons and 5β-stanols such as coprostanol can be used to determine pollutant loading from oil spillage or sewage and the phenanthrene/methylphenanthrene ratio can be used specifically as an indicator of wood burning N-alkanes and thermochemolysis products in cores can show the sensitivity of sediments to changes in land use patterns near the land margin The relationship between marine and terrestrially derived products in sediment cores can be used to indicate the degree to which land use changes have impacted the pattern of marine biogenic productivity in the area Stable isotope and multivariate analyses are particularly useful for biomarker validation
TL;DR: Findings of persistent benefit encourage the clinical assessment of hypothermia, and should be encouraged to improve the clinical Assessment of Hypothermia.
Abstract: Delayed but prolonged hypothermia persistently decreases cell death and functional deficits after global cerebral ischemia in rodents. Postischemic hypothermia also reduces infarction after middle cerebral artery occlusion (MCAO) in rat. Because initial neuroprotection is sometimes transient and may not subserve functional recovery, especially on demanding tasks, the authors examined whether postischemic cooling would persistently reduce infarction and forelimb reaching deficits after MCAO. Male spontaneously hypertensive rats were trained to retrieve food pellets in a staircase test that measures independent forelimb reaching ability. Later, rats underwent 90 minutes of normothermic MCAO, through a microclip, or sham operation. In some rats, prolonged cooling (33 degrees C for 24 hours and then 35 degrees C for 24 hours) began 2.5 hours after the onset of ischemia (60 minutes after the start of reperfusion; n = 17 with subsequently 1 death) or sham procedures (n = 4), whereas untreated sham (n = 4) and ischemic (n = 16 with subsequently 1 death) rats maintained normothermia. An indwelling abdominal probe continually measured core temperature, and an automated fan and water spray system was used to produce hypothermia. One month later rats were reassessed in the staircase test over five days and then killed. The contralateral limb impairment in food pellet retrieval was completely prevented by hypothermia (P = 0.0001). Hypothermia reduced an infarct volume of 67.5 mm3 after untreated ischemia to 35.8 mm3 (P < 0.0001). These findings of persistent benefit encourage the clinical assessment of hypothermia.
TL;DR: The character of health and illness narratives are considered as a function of the personal, interpersonal, positional and societal levels of analysis within health psychology.
Abstract: The past 10-15 years have seen a rapid increase in the study of narrative across all the social sciences. It is sometimes assumed that narrative has the same meaning irrespective of the context in which it is expressed. This article considers different levels of narrative analysis within health psychology. Specifically, it considers the character of health and illness narratives as a function of the personal, interpersonal, positional and societal levels of analysis. At the personal level of analysis narratives are portrayed as expressions of the lived experience of the narrator. At the interpersonal level of analysis the narrative is one that is co-created in dialogue. At the positional level of analysis the analysis considers the differences in social position between the narrator and the listener. The societal level of analysis is concerned with the socially shared stories that are characteristic of certain communities or societies. The challenge is to articulate the connections between these different levels of narrative analysis and to develop strategies to promote emancipatory narratives.
TL;DR: In this paper, the authors apply a threshold regression model to test for asymmetric pricing in the retail gasoline market in Canada, using weekly data for the period January 1990 to December 1996, and present results for 13 Canadian cities for both premium and regular gasoline.
TL;DR: The liver is the major site of gluconeogenesis, the major organ of amino acid catabolism and the only organ with a complete urea cycle; these metabolic capabilities are related, and these relationships are best exemplified by an examination of the disposal of the daily protein load.
Abstract: The liver is the major site of gluconeogenesis, the major organ of amino acid catabolism and the only organ with a complete urea cycle. These metabolic capabilities are related, and these relationships are best exemplified by an examination of the disposal of the daily protein load. Adults, ingesting a typical Western diet, will consume approximately 100 g protein/d; the great bulk of this is metabolized by the liver. Although textbooks suggest that these amino acids are oxidized in the liver, total oxidation cannot occur within the confines of hepatic oxygen uptake and ATP homeostasis. Rather, most amino acids are oxidized only partially in the liver, with the bulk of their carbon skeleton being converted to glucose. The nitrogen is converted to urea and, to a lesser extent, to glutamine. The integration of the urea cycle with gluconeogenesis ensures that the bulk of the reducing power (NADH) required in the cytosol for gluconeogenesis can be provided by ancillary reactions of the urea cycle. Glutamate is at the center of these metabolic events for three reasons. First, through the well-described transdeamination system involving aminotransferases and glutamate dehydrogenase, glutamate plays a key catalytic role in the removal of alpha-amino nitrogen from amino acids. Second, the "glutamate family" of amino acids (arginine, ornithine, proline, histidine and glutamine) require the conversion of these amino acids to glutamate for their metabolic disposal. Third, glutamate serves as substrate for the synthesis of N-acetylglutamate, an essential allosteric activator of carbamyl phosphate synthetase I, a key regulatory enzyme in the urea cycle.
TL;DR: The antioxidant activity of crude tannins of canola and rapeseed hulls was evaluated by β-carotene-linoleate, α,α-diphenyl-β-picrylhydrazyl (DPPH) radical, and reducing power assays.
Abstract: The antioxidant activity of crude tannins of canola and rapeseed hulls was evaluated by β-carotene-linoleate, α,α-diphenyl-β-picrylhydrazyl (DPPH) radical, and reducing power assays. Crude tannins were extracted from three samples of Cyclone canola (high-tannin) hulls and Kolner, Ligaret, and Leo Polish rapeseed (low-tannin) hulls with 70% (vol/vol) acetone. The total phenolic content in crude tannin extracts ranged between 128 and 296 mg of sinapic acid equivalents per 1 g of extract. The ultraviolet spectra of methanolic solution of canola extracts showed two absorption maxima (282 and 309 nm), whereas those of rapeseed extracts exhibited a single maximum (326 nm). Crude tannins isolated from canola hulls exerted significantly (P<0.025) greater antioxidant activity than those from rapeseed in all three assays. The scavenging effect of all crude tannins, at a dose of 1 mg, on the DPPH radical ranged from 35.2 to 50.5%. The reducing power of Cyclone canola hull extracts on potassium ferricyanide was significantly (P≤0.0025) greater than that of rapeseed hull extracts, and the observed data correlated well (r=0.966; P=0.002) with the total content of phenolics present.
TL;DR: A significant role for the liver is indicated in the regulation of plasma homocysteine levels in rats fed a high protein diet enriched with serine, and in vivo effects of serine were examined.
Abstract: Recent evidence suggests that an increased plasma concentration of the sulphur amino acid homocysteine is a risk factor for the development of vascular disease. The tissue(s) responsible for homocysteine production and export to the plasma are not well known. However, given the central role of the liver in amino acid metabolism, we developed a rat primary hepatocyte model in which homocysteine (and cysteine) production and export were examined. The dependence of homocysteine export from incubated hepatocytes on methionine concentration fitted well to a rectangular hyperbola, with half-maximal homocysteine export achieved at methionine concentrations of approx. 0.44 mM. Hepatocytes incubated with 1 mM methionine and 1 mM serine (a substrate for the transulphuration pathway of homocysteine removal) produced and exported significantly less homocysteine (25-40%) compared with cells incubated with 1 mM methionine alone. The effects of dietary protein on homocysteine metabolism were also examined. Rats fed a 60% protein diet had a significantly increased total plasma homocysteine level compared with rats fed a 20% protein diet. In vitro effects of dietary protein were examined using hepatocytes isolated from animals maintained on these diets. When incubated with 1 mM methionine, hepatocytes from rats fed the high protein diet exported significantly more homocysteine compared with hepatocytes from rats fed the normal protein diet. Inclusion of serine significantly lowered homocysteine export in the normal protein group, but the effect was more marked in the high protein group. In vivo effects of serine were also examined. Rats fed a high protein diet enriched with serine had significantly lower total plasma homocysteine (25-30%) compared with controls. These data indicate a significant role for the liver in the regulation of plasma homocysteine levels.
TL;DR: There is some evidence of a gradual increase in disorder as the drying layer become thinner, but no sudden transition, in contrast to what has been seen in previous experiments.
Abstract: We have studied shrinkage-crack patterns which form when a thin layer of an alumina/water slurry dries. Both isotropic and directional drying were studied. The dynamics of the pattern formation process and the geometric properties of the isotropic crack patterns are similar to what is expected from recent models, assuming weak disorder. There is some evidence of a gradual increase in disorder as the drying layer become thinner, but no sudden transition, in contrast to what has been seen in previous experiments. The morphology of the crack patterns is influenced by drying gradients and front propagation effects, with sharp gradients having a strong orienting and ordering effect.