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Effect
Kinds of Effect Terms modified by Effect Selected AbstractsTHE EARNINGS EFFECT OF EDUCATION AT COMMUNITY COLLEGESCONTEMPORARY ECONOMIC POLICY, Issue 1 2010DAVE E. MARCOTTE In this paper, I make use of data from the 2000 follow-up of the National Education Longitudinal Survey postsecondary education transcript files to extend what is known about the value of education at community colleges. I examine the effects of enrollment in community colleges on students' subsequent earnings. I estimate the effects of credits earned separately from credentials because community colleges are often used as a means for students to engage in study not necessarily leading to a degree or certificate. I find consistent evidence of wage and salary effects of both credits and degrees, especially for women. There is no substantial evidence that enrollment in vocational rather than academic coursework has a particularly beneficial effect, however. (JEL I2, J24) [source] THE EFFECT OF COUNTY-LEVEL PRISON POPULATION GROWTH ON CRIME RATES,CRIMINOLOGY AND PUBLIC POLICY, Issue 2 2006TOMISLAV V. KOVANDZIC Research Summary: Prior macro-level studies examining the impact of prison population growth on crime rates have produced widely varying results. Studies using national-level time series data find large impacts of prison growth on crime, whereas those using state panel data find more modest ones. Critics of the former studies maintain that the estimates are implausibly large, arguing that the effects are instead due to analysts' inability to control for potential confounding factors. Conversely, critics of the latter studies argue that they underestimate the total impacts of imprisonment by failing to account for potential free-riding effects. This study uses panel data for 58 Florida counties for 1980 to 2000 to reexamine the link between prison population growth and crime. Unlike previous studies, we find no evidence that increases in prison population growth covary with decreases in crime rates. Policy Implications: Our findings suggest that Florida policymakers carefully weigh the costs and benefits of their continued reliance on mass incarceration against the potential costs and benefits of alternatives. If the costs of mass incarceration do not return appreciable benefits, i.e., a reduction in crime, it is time to reconsider our approach to crime and punishment. Other research offers evidence of crime prevention programs operating inside the criminal justice system and in communities that hold promise for reducing crime; our findings indicate that policymakers carefully consider these options as a way to achieve their goals. [source] THE CRIME-CONTROL EFFECT OF INCARCERATION: DOES SCALE MATTER?,CRIMINOLOGY AND PUBLIC POLICY, Issue 2 2006RAYMOND V. LIEDKA Research Summary: Several prominent empirical studies estimate models of a constant proportional effect of prison on crime, finding that effect is substantial and negative. A separate literature argues against the crime-reducing effect of prison but mainly on theoretical grounds. This second literature suggests that the elasticity of the prison/crime relationship is not constant. We provide a model that nests these two literatures. Using data from the United States over 30 years, we find strong evidence that the negative relationship between prison and crime becomes less strongly negative as the scale of imprisonment increases. This revisionist model indicates that (1) at low levels of incarceration, a constant elasticity model underestimates the negative relationship between incarceration and crime, and (2) at higher levels of incarceration, the constant elasticity model overstates the negative effect. Policy Implications: These results go beyond the claim of declining marginal returns, instead finding accelerating declining marginal returns. As the prison population continues to increase, albeit at a slower rate, after three decades of phenomenal growth, these findings provide an important caution that for many jurisdictions, the point of accelerating declining marginal returns may have set in. Any policy discussion of the appropriate scale of punishment should be concerned with the empirical impact of this expensive and intrusive government intervention. [source] EFFECT OF PARAPROSTHETIC MODERETE TO SEVERE MITRAL REGURGITATION ON EMBOLIC EVENTS IN PATIENTS WITH PROSTHETIC MITRAL VALVESECHOCARDIOGRAPHY, Issue 5 2004C. Cevik Thromboembolism is the major chronic risk for patients with mechanical prosthetic heart valves. Although optimal oral anticoagulantion is the key determinant for embolic events (EE) in these patients; other factors also contribute to this complication. We studied the prevalence and determinants of embolic events in patients with mitral prosthetic heart valves undergoing transesophageal echocardiography (TEE). 210 patients (86 male and 124 female, mean age 45.1 +/, 9.6 years) underwent a TEE study for evaluation of prosthetic valve functions. Clinical and TEE findings of the patients were as follows: Atrial fibrillation in 132 (%62) patients, prosthetic valve thrombus in 55 (%26) suboptimal INR (INR < 1.8) in 61 (%29) pts, left atrial spontenous echocardiographic contrast (SEC) in 31 (%14) patients, paraprosthetic moderete-severe mitral regurgitation (MR) in 28 (%13), left atrial (LA) and/or left atrial appendix (LAA) thrombus in 41 (%19), LA and/or LAA outflow velocities <0.25 m/sn in 21 patiens (%10), left atrial diameter >6 cm in 47 (%22). 72 patients had a history of EE in the previous 6 months (%34). In no patients were there any EE in the presence of paraprosthetic moderate to severe MR. Both with univariate and multivariate analysis presence of prosthetic valve and LA and/or LAA thrombus, absence of paraprosthetic moderete-severe MR, suboptimal INR, atrial fibrillation were found to be independent predictors for embolic events. Conclusions: Although the presence of prosthetic valve and LA and/or LAA thrombus, suboptimal INR, and AF predict EE, clinical and echocardiographic data support the protective effect of paraprosthetic moderate to severe MR against EE in pts with mitral prosthetic valves. [source] EVOLUTIONARY MECHANISMS UNDERLYING THE EFFECT OF SUBJECTIVE SOCIAL STATUS ON SMOKING ABSTINENCE: ULTIMATE VERSUS PROXIMATE EXPLANATIONSADDICTION, Issue 8 2010HENRI-JEAN AUBIN No abstract is available for this article. [source] THE EFFECT OF REWARDS AND SANCTIONS IN PROVISION OF PUBLIC GOODSECONOMIC INQUIRY, Issue 4 2007MARTIN SEFTON A growing number of field and experimental studies focus on the institutional arrangements by which individuals are able to solve collective action problems. Important in this research is the role of reciprocity and institutions that facilitate cooperation via opportunities for monitoring, sanctioning, and rewarding others. Sanctions represent a cost to both the participant imposing the sanction and the individual receiving the sanction. Rewards represent a zero-sum transfer from participants giving to those receiving rewards. We contrast reward and sanction institutions in regard to their impact on cooperation and efficiency in the context of a public goods experiment. (JEL C92) [source] THE PROCYCLICAL LEVERAGE EFFECT OF COLLATERAL VALUE ON BANK LOANS,EVIDENCE FROM THE TRANSACTION DATA OF TAIWANECONOMIC INQUIRY, Issue 2 2007NAN-KUANG CHEN We investigated the empirical relationship between firms' collateral values and land-secured loans over asset price cycles. A simultaneous equation model of loan demand and supply was estimated using a transaction-level data set from Taiwan. The data set contains collateral information and identifies lenders and borrowers. We found that the value of collateralizable assets has positive and significant effects on loan amounts and that the leverage effect of collateral is procyclical to asset price cycles. Firms in the electronics industry, the star industry in the sample period, are found to borrow more than other firms do at each marginal dollar of collateral. (JEL C50, E30, G20) [source] EVOLUTIONARY ANALYSIS OF A KEY FLORAL TRAIT IN AQUILEGIA CANADENSIS (RANUNCULACEAE): GENETIC VARIATION IN HERKOGAMY AND ITS EFFECT ON THE MATING SYSTEMEVOLUTION, Issue 7 2007Christopher R. Herlihy The mating system of flowering plant populations evolves through selection on genetically based phenotypic variation in floral traits. The physical separation of anthers and stigmas within flowers (herkogamy) is expected to be an important target of selection to limit self-fertilization. We investigated the pattern of phenotypic and genetic variation in herkogamy and its effect of self-fertilization in a broad sample of natural populations of Aquilegia canadensis, a species that is highly selfing despite strong inbreeding depression. Within natural populations, plants exhibit substantial phenotypic variation in herkogamy caused primarily by variation in pistil length rather than stamen length. Compared to other floral traits, herkogamy is much more variable and a greater proportion of variation is distributed among rather than within individuals. We tested for a genetic component of this marked phenotypic variation by growing naturally pollinated seed families from five populations in a common greenhouse environment. For three populations, we detected a significant variation in herkogamy among families, and a positive regression between parental herkogamy measured in the field and progeny herkogamy in the greenhouse, suggesting that there is often genetic variation in herkogamy within natural populations. We estimated levels of self-fertilization for groups of flowers that differed in herkogamy and show that, as expected, herkogamy was associated with reduced selfing in 13 of 19 populations. In six of these populations, we performed floral emasculations to show that this decrease in selfing is due to decreased autogamy (within-flower selfing), the mode of selfing that herkogamy should most directly influence. Taken together, these results suggest that increased herkogamy should be selected to reduce the production of low-quality selfed seed. The combination of high selfing and substantial genetic variation for herkogamy in A. canadensis is enigmatic, and reconciling this observation will require a more integrated analysis of how herkogamy influences not only self-fertilization, but also patterns of outcross pollen import and export. [source] A NEGATIVE RELATIONSHIP BETWEEN MUTATION PLEIOTROPY AND FITNESS EFFECT IN YEASTEVOLUTION, Issue 6 2007Tim F. Cooper It is generally thought that random mutations will, on average, reduce an organism's fitness because resulting phenotypic changes are likely to be maladaptive. This relationship leads to the prediction that mutations that alter more phenotypic traits, that is, are more pleiotropic, will impose larger fitness costs than mutations that affect fewer traits. Here we present a systems approach to test this expectation. Previous studies have independently estimated fitness and morphological effects of deleting all nonessential genes in Saccharomyces cerevisiae. Using datasets generated by these studies, we examined the relationship between the pleiotropic effect of each deletion mutation, measured as the number of morphological traits differing from the parental strain, and its effect on fitness. Pleiotropy explained ,18% of variation in fitness among the mutants even once we controlled for correlations between morphological traits. This relationship was robust to consideration of other explanatory factors, including the number of protein,protein interactions and the network position of the deleted genes. These results are consistent with pleiotropy having a direct role in affecting fitness. [source] THE FITNESS EFFECT OF MUTATIONS ACROSS ENVIRONMENTS: A SURVEY IN LIGHT OF FITNESS LANDSCAPE MODELSEVOLUTION, Issue 12 2006Guillaume Martin Abstract The fitness effects of mutations on a given genotype are rarely constant across environments to which this genotype is more or less adapted, that is, between more or less stressful conditions. This can have important implications, especially on the evolution of ecological specialization. Stress is thought to increase the variance of mutations' fitness effects, their average, or the number of expressed mutations. Although empirical evidence is available for these three mechanisms, their relative magnitude is poorly understood. In this paper, we propose a simple approach to discriminate between these mechanisms, using a survey of empirical measures of mutation effects in contrasted environments. This survey, across various species and environments, shows that stress mainly increases the variance of mutations effects on fitness, with a much more limited impact on their average effect or on the number of expressed mutations. This pattern is consistent with a simple model in which fitness is a Gaussian function of phenotypes around an environmentally determined optimum. These results suggest that a simple, mathematically tractable landscape model may not be quantitatively as unrealistic as previously suggested. They also suggest that mutation parameter estimates may be strongly biased when measured in stressful environments. [source] THE EFFECT OF SELF-FERTILIZATION, INBREEDING DEPRESSION, AND POPULATION SIZE ON AUTOPOLYPLOID ESTABLISHMENEVOLUTION, Issue 9 2005Joseph H. Rausch Abstract The minority cytotype exclusion principle describes how random mating between diploid and autotetraploid cytotypes hinders establishment of the rare cytotype. We present deterministic and stochastic models to ascertain how selfing, inbreeding depression, unreduced gamete production, and finite population size affect minority cytotype exclusion and the establishment of autotetraploids. Results demonstrate that higher selfing rates and lower inbreeding depression in autotetraploids facilitate establishment of autotetraploid populations. Stochastic effects due to finite population size increase the probability of polyploid establishment and decrease the mean time to tetraploid fixation. Our results extend the minority cytotype exclusion principle to include important features of plant reproduction and demonstrate that variation in mating system parameters significantly influences the conditions necessary for polyploid establishment. [source] INCREASED RATES OF MOLECULAR EVOLUTION IN AN EQUATORIAL PLANT CLADE: AN EFFECT OF ENVIRONMENT OR PHYLOGENETIC NONINDEPENDENCE?EVOLUTION, Issue 1 2005Jeremy M. Brown Abstract A recent study of environmental effects on rates of molecular evolution in the plant subgenus Mearnsia shows that species occurring in more equatorial latitudes have higher rates of substitution in rDNa sequences as compared to their more southerly congeners (Wright et al. 2003). However, we believe that the statistical approach employed by Wright et al. (2003) insufficiently accounts for the phylogenetic nonindependence of the species examined, given that all six equatorial species of Mearnsia form a clade. To distinguish between the effect of latitude and that of phylogenetic nonindependence, we have employed a variety of comparative approaches that use independent contrasts to test for an effect of environment across this entire subgenus. We find very little evidence for an effect of latitude on rate of molecular evolution using these approaches and believe that the shared evolutionary history of the clade is a plausible explanation of the apparent rate difference between equatorial and subequatorial Mearnsia species. [source] ALLEE EFFECT AND SELF-FERTILIZATION IN HERMAPHRODITES: REPRODUCTIVE ASSURANCE IN DEMOGRAPHICALLY STABLE POPULATIONSEVOLUTION, Issue 12 2004Pierre-Olivier Cheptou Abstract The fact that selfing increases seed set (reproductive assurance) has often been put forward as an important selective force for the evolution of selfing. However, the role of reproductive assurance in hermaphroditic populations is far from being clear because of a lack of theoretical work. Here, I propose a theoretical model that analyzes selffertilization in the presence of reproductive assurance. Because reproductive assurance directly influences the per capita growth rate, I developed an explicit demographic model for partial selfers in the presence of reproductive assurance, specifically when outcrossing is limited by the possibility of pollen transfer (Allee effect). Mating system parameters are derived as a function of the underlying demographical parameters. The functional link between population demography and mating system parameters (reproductive assurance, selfing rate) can be characterized. The demographic model permits the analysis of the evolution of self-fertilization in stable populations when reproductive assurance occurs. The model reveals some counterintuitive results such as the fact that increasing the fraction of selfed ovules can, in certain circumstances, increase the fraction of outcrossed ovules. Moreover, I demonstrate that reproductive assurance per se cannot account for the evolution of stable mixed selfing rates. Also, the model reveals that the extinction of outcrossing populations depends on small changes in population density (ecological perturbations), while the transition from outcrossing to selfing can, in certain cases, lead the population to extinction (evolutionary suicide). More generally, this paper highlights the fact that self-fertilization affects both the dynamics of individuals and the dynamics of selfing genes in hermaphroditic populations. [source] THE EFFECT OF ALTERNATIVE PREY ON THE DYNAMICS OF IMPERFECT BATESIAN AND MÜLLERIAN MIMICRIESEVOLUTION, Issue 6 2004Leena Lindström Abstract Both Batesian and Müllerian mimicries are considered classical evidence of natural selection where predation pressure has, at times, created a striking similarity between unrelated prey species. Batesian mimicry, in which palatable mimics resemble unpalatable aposematic species, is parasitic and only beneficial to the mimics. By contrast, in classical Müllerian mimicry the cost of predators' avoidance learning is shared between similar unpalatable co-mimics, and therefore mimicry benefits all parties. Recent studies using mathematical modeling have questioned the dynamics of Müllerian mimicry, suggesting that fitness benefits should be calculated in a way similar to Batesian mimicry; that is, according to the relative unpalatability difference between co-mimics. Batesian mimicry is very sensitive to the availability of alternative prey, but the effects of alternative prey for Müllerian dynamics are not known and experiments are rare. We designed two experiments to test the effect of alternative prey on imperfect Batesian and Müllerian mimicry complexes. When alternative prey were scarce, imperfect Batesian mimics were selected out from the population, but abundantly available alternative prey relaxed selection against imperfect mimics. Birds learned to avoid both Müllerian models and mimics irrespective of the availability of alternative prey. However, the rate of avoidance learning of models increased when alternative prey were abundant. This experiment suggests that the availability of alternative prey affects the dynamics of both Müllerian and Batesian mimicry, but in different ways. [source] THE EFFECT OF EPISTASIS ON THE EXCESS OF THE ADDITIVE AND NONADDITIVE VARIANCES AFTER POPULATION BOTTLENECKSEVOLUTION, Issue 5 2002Carlos López-Fanjul Abstract The effect of population bottlenecks on the components of the genetic variance generated by two neutral independent epistatic loci has been studied theoretically (VA, additive; VD, dominant; VAA, additive × additive; VAD, additive × dominant; VDD; dominant × dominant components of variance). Nonoverdominance and overdominance models were considered, covering all possible types of marginal gene action at the single locus level. The variance components in an infinitely large panmictic population (ancestral components) were compared with their expected values at equilibrium, after t consecutive bottlenecks of equal size N (derived components). Formulae were obtained in terms of allele frequencies and effects at each locus and the corresponding epistatic value. An excess of VA after bottlenecks can be assigned to two sources: (1) the spatiotemporal changes in the marginal average effects of gene substitution ai, which are equal to zero only for additive gene action within and between loci; and (2) the covariance between a2i and the heterozygosity at the loci involved, which is generated by dominance, with or without epistasis. Numerical examples were analyzed, indicating that an increase in VA after bottlenecks will only occur if its ancestral value is minimal or very small. For the nonoverdominance model with weak reinforcing epistasis, that increase has been detected only for extreme frequencies of the negative allele at one or both loci. With strong epistasis, however, this result can be extended to a broad range of intermediate frequencies. With no epistasis, the same qualitative results were found, indicating that dominance can be considered as the primary cause of an increase in VA following bottlenecks. In parallel, the derived total nonadditive variance exceeded its ancestral value (VNA= VD+ VAA+VAD+ VDD) for a range of combinations of allele frequencies covering those for an excess of VA and for very large frequencies of the negative allele at both loci. For the overdominance model, an increase in VA and VNA was respectively observed for equilibrium (intermediate) frequencies at one or both loci or for extreme frequencies at both loci. For all models, the magnitude of the change of VA and VNA was inversely related to N and t. At low levels of inbreeding, the between-line variance was not affected by the type of gene action. For the models considered, the results indicate that it is unlikely that the rate of evolution may be accelerated after population bottlenecks, in spite of occasional increments of the derived VA over its ancestral value. [source] THE COMBINED EFFECT OF DONATION PRICE AND ADMINISTRATIVE INEFFICIENCY ON DONATIONS TO US NONPROFIT ORGANIZATIONSFINANCIAL ACCOUNTABILITY & MANAGEMENT, Issue 1 2009Fred A. Jacobs We examine the effects that two accounting measures of nonprofit organization (NPO) inefficiency, administrative inefficiency and donation price, have on donations to US NPOs using a better-specified model and industry-specific samples. Although numerous studies examine the effect that donation price has on donations (e.g., Marudas and Jacobs, 2006; Marudas, 2004; Khanna and Sandler, 2000; and Tinkelman, 1999), only three studies examine the effect of administrative inefficiency on donations (Tinkelman and Mankaney, 2007; Frumkin and Kim, 2001; and Greenlee and Brown, 1999). However, none of these studies tests donation price and administrative inefficiency in one model and only two test industry-specific samples of NPOs. We find that misspecifying the model by including only one of these two inefficiency measures creates substantial bias and the effect of administrative inefficiency on donations varies substantially across industries. Administrative inefficiency has a significantly negative effect on donations to NPOs in the full sample and the philanthropy sample, but no significant effect on donations to NPOs in the arts, education, health, or human services samples. Furthermore, donation price has a significantly negative effect on donations to NPOs in the full sample and the education, health and human services samples, but not in the arts or philanthropy samples. Results are also reported for the other variables in the model , government support, program service revenue, fundraising and organizational age, wealth and size. [source] VARYING EFFECT OF FERTILITY DETERMINANTS AMONG MIGRANT AND INDIGENOUS FEMALES IN THE TRANSITIONAL AGRO-ECOLOGICAL ZONE OF GHANAGEOGRAFISKA ANNALER SERIES B: HUMAN GEOGRAPHY, Issue 1 2007Samuel Nii Ardey Codjoe ABSTRACT. The transitional agro-ecological zone of Ghana, located between the richly endowed south and the impoverished north, has attracted seasonal and permanent farm migrants, mainly from northern Ghana, who now live side by side with the indigenous people. While migrants have higher numbers of Muslims, indigenous people are mainly Christians. Although the majority of the migrants live in migrant quarters with less favourable socio-economic conditions, they are more successful farmers and therefore wealthier. The objectives are to examine the varying effect of fertility determinants among migrants and indigenous females. This paper uses data collected in 2002 among 194 females aged 15 to 49 years. Multiple regression models are used to assess fertility determinants. Results show that although migrant households were wealthier, migrant females were more traditional. They had more children living in foster care, and a lower proportion of them approved of men participating in household activities. In addition, they were less well educated, recorded higher infant mortality, gave birth earlier and used less contraception. Furthermore, while a female's migration status is statistically significant so far as non-proximate determinants of fertility are concerned, the same variable is not significant with respect to proximate determinants. In addition, a married female migrant would on average have almost one more child compared to her indigenous counterpart, and migrant females who had experienced the loss of a child would on average have 2.5 more children compared to their indigenous counterparts. Finally, more affluent migrant females have 0.08 fewer children compared to their indigenous counterpart. [source] THE EFFECT OF MATERNAL EMPLOYMENT AND CHILD CARE ON CHILDREN'S COGNITIVE DEVELOPMENT,INTERNATIONAL ECONOMIC REVIEW, Issue 4 2008Raquel Bernal This article develops and estimates a dynamic model of employment and child care decisions of women after childbirth to evaluate the effects of these choices on children's cognitive ability. We use data from the National Longitudinal Survey of Youth to estimate it. Results indicate that the effects of maternal employment and child care on children's ability are negative and sizable. Having a mother that works full-time and uses child care during one year is associated with a reduction in ability test scores of approximately 1.8% (0.13 standard deviations). We assess the impact of policies related to parental leave and child care on children's outcomes. [source] EFFECT OF VITAMIN D3 ON QUALITY OF LIFEJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 12 2009Ghulamullah Shahzad MD No abstract is available for this article. [source] EFFECT OF DIABETES SERVICE FOR OLDER PEOPLE ON LENGTH OF HOSPITAL STAYJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 11 2008Ryan Chiang MBChB No abstract is available for this article. [source] EFFECT OF TEMPERATURE ON SWALLOWING REFLEX IN ELDERLY PATIENTS WITH ASPIRATION PNEUMONIAJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 12 2004Aya Watando MD No abstract is available for this article. [source] EFFECT OF A LIGHT-EMITTING DIODE ON COMPOSITE POLYMERIZATION SHRINKAGE AND HARDNESSJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 2 2005Kraig S. Vandewalle DDS [source] PROTEINASES IN HYBRID CATFISH VISCERA: CHARACTERIZATION AND EFFECT OF EXTRACTION MEDIAJOURNAL OF FOOD BIOCHEMISTRY, Issue 4 2010SAPPASITH KLOMKLAO ABSTRACT Proteolytic activity from viscera extract of hybrid catfish (Clarias macrocephalus × Clarias gariepinus) was investigated. Optimal pH and temperature for casein hydrolysis were 9.0 and 50C, respectively. The enzyme was stable to heat treatment up to 40C and over a pH range of 7,11 for 30,120 min. The proteolytic activity was effectively inhibited by soybean trypsin inhibitor, benzamidine, phenylmethylsulfonyl fluoride and N -p-tosyl-L-lysine chloromethyl ketone. Activities of the viscera extract continuously decreased as NaCl concentration increased, while activities increased as CaCl2 concentration increased. Based on the proteinase activity of zones separated by electrophoresis, the molecular mass of the major proteinases in hybrid catfish viscera was 23 and 20 kDa. The effect of extraction media on recovery of proteinases was also studied. Extraction of the viscera powder with 50 mM Tris-HCl, pH 7.0 containing 0.5 M NaCl and 0.2% (v/v) Brij 35 rendered a higher recovery of proteinase activity than other extractants tested (P < 0.05). The results suggested that major proteinases in hybrid catfish viscera were heat-activated alkaline proteinases, most likely trypsin-like serine proteinases. PRACTICAL APPLICATIONS Hybrid catfish viscera is an abundant and underutilized resource that can be used as a unique proteinase source. Proteinase from various sources catalyzes the hydrolysis of peptide bonds. Thus, it is expected that like other proteinases, hybrid catfish proteinase would be useful in biomedical, food and beverage application. Moreover, the presented extraction media could be adopted to recover the trypsin-like serine proteinase from hybrid catfish viscera, which is currently a solid waste of Pa-duk-ra industry. [source] EFFECT OF SALTS AND POLYETHYLENE GLYCOLS ON THE PARTITIONING AND RECOVERY OF TRYPSIN FROM HYBRID CATFISH VISCERA IN AQUEOUS TWO-PHASE SYSTEMSJOURNAL OF FOOD BIOCHEMISTRY, Issue 4 2010SAPPASITH KLOMKLAO ABSTRACT The partitioning behavior of trypsin from hybrid catfish viscera in aqueous two-phase systems (ATPS) was studied. Factors such as polyethylene glycol (PEG) molecular mass and concentration, as well as types and concentration of salts, affected protein separation. Trypsin partitioned mainly in the top PEG-rich phase. ATPS formed by PEG of molecular weight 4,000 (20%, w/w) and NaH2PO4 (20%, w/w) showed the best capability for trypsin purification from hybrid catfish viscera. Under such conditions, the highest specific activity (30.05 units/µg protein) and purification (27.3-fold), were obtained. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed that the enzyme after ATPS separation was near homogeneity and based on the activity staining, the band intensity of enzyme in ATPS fraction increased, indicating the greater specific activity of the viscera extract. The partitioned enzyme displayed optimal activity at pH 9.0 and 50C, respectively. The enzyme was stable up to 40C and within the pH range of 8,12. The enzyme exhibited a progressive decrease in activity with increasing NaCl concentration. PRACTICAL APPLICATIONS This paper describes the separation and recovery of trypsin from hybrid catfish viscera in ATPS and its properties. ATPS provides an efficient and attractive method for partitioning and recovery of trypsin from hybrid catfish viscera. Trypsins from various sources catalyze the hydrolysis of peptide bonds on the carboxyl sides of arginine and lysine. Therefore, it is expected that like other trypsins, trypsin after ATPS separation from hybrid catfish viscera could be useful in the biomedical, food and beverage industries. [source] EFFECT OF BUTYRIC ACID SUPPLEMENTATION ON SERUM AND RENAL ANTIOXIDANT ENZYME ACTIVITIES IN STREPTOZOTOCIN-INDUCED DIABETIC RATSJOURNAL OF FOOD BIOCHEMISTRY, Issue 2010A. PUNEETH KUMAR ABSTRACT Reactive oxygen metabolites, which are constant products of normal aerobic cell metabolism, play a key role in worsening the pathophysiological complications of diabetes. The present investigation was aimed at understanding the effect of butyric acid supplementation along with wheatbran and guar gum on serum and renal antioxidant enzyme activities and lipid peroxidation in streptozotocin (STZ)-induced diabetic rats. Activities of superoxide dismutase, catalase, glutathione peroxidase were evaluated in serum and kidney of control and experimental rats. Results clearly showed that the altered activity of the enzymes during diabetes was significantly ameliorated by butyric acid (500 mg/kg body weight/day) supplementation compared with other experimental groups. Further, the increased lipid peroxidation in serum and kidney of diabetic rats was also significantly reduced in butyric acid-supplemented diabetic rats. The study led us to conclude that butyric acid exert antioxidant property, thereby minimizing oxidative stress induced diabetes and its related complications. PRACTICAL APPLICATIONS Butyric acid , a product of dietary fiber fermentation , is a four-carbon fatty acid, which has wide range of application in disease management. This product is involved in various physiological functions of body like cell differentiation, apoptosis, colonic homeostasis, histone acetylation, etc. It is also known to decrease the incidence of bowel cancer and some of its analogues are shown to selectively improve glucose-stimulated insulin release and glucose tolerance in both normal and diabetic rats. This study aims to evaluate the beneficial effects of butyric acid supplementation on oxidative stress-induced diabetic complications in rats. [source] FREE RADICAL-SCAVENGING ACTIVITIES OF LOW MOLECULAR WEIGHT CHITIN OLIGOSACCHARIDES LEAD TO ANTIOXIDANT EFFECT IN LIVE CELLSJOURNAL OF FOOD BIOCHEMISTRY, Issue 2010DAI-NGHIEP NGO ABSTRACT Chitin oligosaccharides (NA-COS) with low molecular weight distribution of 229.21,593.12 Da were produced from crab chitin by acid hydrolysis. They showed reducing power and scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH) (Sigma Chemical Co., St. Louis, MO), hydroxyl and alkyl radicals. It was observed that the radical-scavenging activity of NA-COS increased in a dose-dependent manner. Their IC50 values for DPPH, hydroxyl and alkyl radicals were 0.8, 1.75 and 1.14 mg/mL, respectively. Furthermore, NA-COS exhibited the inhibitory effect on the oxidative damage of DNA from human lymphoma U937 (American Type Culture Collection, Manassas, VA) and the direct radical-scavenging effect in human fibrosarcoma cells (HT1080) (American Type Culture Collection) in 2,,7,-dichlorofluorescin diacetate (DCFH-DA) assay (Molecular Probes Inc., Eugene, OR). The results suggest that NA-COS can exert antioxidant effect in live cells and have the potential to be applied to food supplements or nutraceuticals. PRACTICAL APPLICATIONS Chitin oligosaccharides (NA-COS) are the hydrolyzed products of chitin (KEUMHO chemical products Co. Ltd., Gyeongbuk, Korea) of which derivatives have shown antioxidant, antimicrobial, anticancer, anti-inflammatory and immunostimulant effects. According to previous studies, NA-COS have beneficial biological activities similar to those of chitin. Furthermore, they are easily soluble in water because of their shorter chain length. Therefore, NA-COS are potentially applicable to improve food quality and human health. [source] EFFECT OF VARIOUS ANTIOXIDANTS ON THE OXIDATIVE STABILITY OF ACID AND ALKALI SOLUBILIZED MUSCLE PROTEIN ISOLATESJOURNAL OF FOOD BIOCHEMISTRY, Issue 2 2009SIVAKUMAR RAGHAVAN ABSTRACT Protein isolates prepared from cod (Gadus morhua) myofibrillar proteins using acid or alkali solubilization are susceptible to oxidative rancidity. Oxidation could be delayed by the exogenous addition of antioxidants. The objective of this research was to compare the efficacy of antioxidants such as ,-tocopherol, butylated hydroxyanisole (BHA) and propyl gallate, to inhibit oxidation in acid- and alkali- solubilized cod protein isolates. Oxidation was catalyzed using cod hemolysate. Oxidation of lipids was monitored by the measurement of thiobarbituric acid reactive substances and painty odor. Results showed that protein isolates prepared using the acid process was significantly (P < 0.05) more susceptible to lipid oxidation than alkali-solubilized protein isolates. Regardless of pH treatments, the efficacy of various antioxidants decreased in the order propyl gallate > BHA > ,-tocopherol. PRACTICAL APPLICATIONS Research has shown that seafood available for human consumption is rapidly getting depleted and that many fish species may become extinct in the next half-century or so. Acid and alkali solubilization methods are recent but well-known techniques used for preparing protein isolates from under-utilized aquatic species and the by-products of seafood industry. Although numerous researchers have studied the use of acid and alkali processes on several sources of seafood, almost no research has been done on the use of antioxidants to protect protein isolates from lipid oxidation. In our research, we have studied the effect of various antioxidants on the oxidative stability of acid- and alkali-solubilized fish myofibrillar proteins. The results from this work will enable the seafood industry to properly identify the process and the type of antioxidants required for making muscle food products with increased oxidative stability. [source] ESR SPECTROSCOPY INVESTIGATION OF ANTIOXIDANT ACTIVITY AND PROTECTIVE EFFECT ON HYDROXYL RADICAL-INDUCED DNA DAMAGE OF ENZYMATIC EXTRACTS FROM PICRORRHIZA KURROAJOURNAL OF FOOD BIOCHEMISTRY, Issue 6 2008SOUNG-HEE CHOI ABSTRACT The potential antioxidant activity of enzymatic extracts from Picrorrhiza kurroa was evaluated on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, hydroxyl radical and alkyl radical-scavenging activities using an electron spin resonance spectrometer (JEOL Ltd., Tokyo, Japan). P. kurroa was enzymatically hydrolyzed by seven carbohydrases and five proteases to prepare water-soluble extracts. The DPPH radical-scavenging activities of the pancreatic trypsin and Amyloglucosidase (AMG) (artificial carbohydrase by Novozyme Nordisk, Bagsvaerd, Denmark) extracts from P. kurroa were the highest among protease and carbohydrase extracts, and 50% inhibitory concentration (IC50) values were 35.58 and 29.03 µg/mL, respectively. The hydroxyl radical-scavenging activity of the Protamex and Viscozyme extracts from P. kurroa were the highest scavenging activities, and the IC50 values were 0.46 and 1.89 mg/mL, respectively. In addition, the Protamex and Maltogenase extracts from P. kurroa showed the highest alkyl radical-scavenging activities, and the IC50 values were 18.03 and 10.66 µg/mL, respectively. The protective effect of the Protamex extracts from P. kurroa on DNA damage which was free radical-induced was 92% at 3 mg/mL. These results indicate that enzymatic extracts of P. kurroa show potent antioxidant activity. PRACTICAL APPLICATIONS Picrorrhiza kurroa could be used to produce protein and carbohydrate extracts with antioxidative activity. Many industrial commercial enzymes such as Promozyme, Celluclast 1.5 L FG, Maltogenase L, Viscozyme L, Termamyl SC, Dextrozyme E, AMG 300 L, Protamex, Flavourzyme 500 MG, Neutrase 0.8 L, Pancreatic Trypsin and Alcalase 2.4 L could be also used to attain the extracts processing the high antioxidative activity. The extracts can be used as natural antioxidants. [source] EFFECT OF ARTIFICIAL FEEDING ON DIGESTIVE EFFICIENCY, GROWTH AND QUALITIES OF MUSCLE AND OOCYTE OF MATURING ATLANTIC MACKEREL (SCOMBER SCOMBRUS L.)JOURNAL OF FOOD BIOCHEMISTRY, Issue 6 2007KRISNA RUNGRUANGSAK-TORRISSEN ABSTRACT Maturing Atlantic mackerel with and without artificial feeding, kept in sea pens (September to May), showed differences in digestive efficiency (protease activity ratio of trypsin to chymotrypsin), muscle growth (concentrations of RNA, protein, RNA/protein ratio and free amino acids [FAA]) and oocyte quality (trypsin-like specific activity, and concentrations of RNA, RNA/protein ratio and FAA). The artificially fed mackerel had higher body weights (1.7 times) but with less white muscle protein concentration (0.5 time), compared to the control group. Both groups showed higher levels of capacity for protein synthesis in the oocytes than in the white muscle, but it was about two times higher in the artificially fed fish whereas about four times higher in the control group. This indicated that, during maturation, development of oocytes and muscle for growth occurred concurrently in higher growth mackerel, while development of oocytes dominated in slower growth fish. A higher trypsin-like specific activity with higher FAA levels in the oocytes from females fed with an artificial diet, compared to the control group, suggested differences in development and quality between the gametes of the fish with different feedings. PRACTICAL APPLICATIONS The work illustrates differences in digestive efficiency and the quality of growth performance (growth and protein metabolism in muscle and oocytes) in fish with different feedings. The use of various methods for evaluating digestive efficiency and the quality of fish growth performance could provide reasonable information for some important biological differences between fish groups, especially when the number of samples are low. It is more advantageous to apply different methods simultaneously than using growth parameter alone in order to study for precise evaluation of the quality of fish growth performance. The methods are very practical for studying food utilization and growth quality of fish in different environmental conditions and with different behaviors in aquaculture as well as in natural ecosystem where food consumption rate and feeding regime cannot be under control. [source] EFFECT OF STORAGE TEMPERATURE ON HISTAMINE FORMATION IN SARDINA PILCHARDUS AND ENGRAULIS ENCRASICOLUS AFTER CATCHJOURNAL OF FOOD BIOCHEMISTRY, Issue 5 2007PIERINA VISCIANO ABSTRACT Histamine formation in Sardina pilchardus and Engraulis encrasicolus as a function of storage temperature was studied. Fish were caught off the Adriatic Coast and were carried immediately to the laboratory. A portion of dorsal muscle from each fish was soon analyzed, while two other portions were examined after storage at two different temperatures (25 and 4C) for 24 and 72 h, respectively. The analyses were carried out by high-performance liquid chromatography (HPLC)-UV and confirmed by HPLC-diode array detector. Histamine concentrations were always higher than the European Community admissible levels in samples stored at 25C. In fish stored at 4C, histamine was detected only in E. encrasicolus. PRACTICAL APPLICATIONS Time experiments were conducted to quantify the histamine formation in scombroid species at two different temperatures. The first assay (24 h, 25C) could reproduce the modality of sale adopted by fishermen or retailers in summer on the one hand, and the maintenance at ambient temperature of semipreserved sardines or anchovies during salting and ripening on the other hand. The second experiment (72 h, 4C) was based on the domestic cold preservation of fish before the consumption, which sometimes occurs some days after purchasing. Even if ice storage is recommended, time/temperature abuse conditions often occur in the fish merchandising chain. The results of this research showed that high histamine concentrations could be found in the analyzed species not only at an abused temperature, but also at a common storage temperature of fish at home. [source] | ||||||||||||||||||||||||||||||||||||||||