Showing papers by "University of Memphis published in 1998"

Tannins and Human Health: A Review

Abstract: Tannins (commonly referred to as tannic acid) are water-soluble polyphenols that are present in many plant foods. They have been reported to be responsible for decreases in feed intake, growth rate, feed efficiency, net metabolizable energy, and protein digestibility in experimental animals. Therefore, foods rich in tannins are considered to be of low nutritional value. However, recent findings indicate that the major effect of tannins was not due to their inhibition on food consumption or digestion but rather the decreased efficiency in converting the absorbed nutrients to new body substances. Incidences of certain cancers, such as esophageal cancer, have been reported to be related to consumption of tannins-rich foods such as betel nuts and herbal teas, suggesting that tannins might be carcinogenic. However, other reports indicated that the carcinogenic activity of tannins might be related to components associated with tannins rather than tannins themselves. Interestingly, many reports indicated negative association between tea consumption and incidences of cancers. Tea polyphenols and many tannin components were suggested to be anticarcinogenic. Many tannin molecules have also been shown to reduce the mutagenic activity of a number of mutagens. Many carcinogens and/or mutagens produce oxygen-free radicals for interaction with cellular macromolecules. The anticarcinogenic and antimutagenic potentials of tannins may be related to their antioxidative property, which is important in protecting cellular oxidative damage, including lipid peroxidation. The generation of superoxide radicals was reported to be inhibited by tannins and related compounds. The antimicrobial activities of tannins are well documented. The growth of many fungi, yeasts, bacteria, and viruses was inhibited by tannins. We have also found that tannic acid and propyl gallate, but not gallic acid, were inhibitory to foodborne bacteria, aquatic bacteria, and off-flavor-producing microorganisms. Their antimicrobial properties seemed to be associated with the hydrolysis of ester linkage between gallic acid and polyols hydrolyzed after ripening of many edible fruits. Tannins in these fruits thus serve as a natural defense mechanism against microbial infections. The antimicrobial property of tannic acid can also be used in food processing to increase the shelf-life of certain foods, such as catfish fillets. Tannins have also been reported to exert other physiological effects, such as to accelerate blood clotting, reduce blood pressure, decrease the serum lipid level, produce liver necrosis, and modulate immunoresponses. The dosage and kind of tannins are critical to these effects. The aim of this review is to summarize and analyze the vast and sometimes conflicting literature on tannins and to provide as accurately as possible the needed information for assessment of the overall effects of tannins on human health.

Rule discovery from time series

Abstract: We consider the problem of finding rules relating patterns in a time series to other patterns in that series, or patterns in one series to patterns in another series A simple example is a rule such as "a period of low telephone call activity is usually followed by a sharp rise in call volume" Examples of rules relating two or more time series are "if the Microsoft stock price goes up and Intel falls, then IBM goes up the next day," and "if Microsoft goes up strongly for one day, then declines strongly on the next day, and on the same days Intel stays about level, then IBM stays about level" Our emphasis is in the discovery of local patterns in multivariate time series, in contrast to traditional time series analysis which largely focuses on global models Thus, we search for rules whose conditions refer to patterns in time series However, we do not want to define beforehand which patterns are to be used; rather, we want the patterns to be formed from the data in the context of rule discovery We describe adaptive methods for finding rules of the above type from time-series data The methods are based on discretizing the sequence by methods resembling vector quantization We first form subsequences by sliding a window through the time series, and then cluster these subsequences by using a suitable measure of time-series similarity The discretized version of the time series is obtained by taking the cluster identifiers corresponding to the subsequence Once the time-series is discretized, we use simple rule finding methods to obtain rules from the sequence We present empirical results on the behavior of the method

Multiple parameters for the comprehensive evaluation of the susceptibility of Escherichia coli to the silver ion

Abstract: The susceptibility of Escherichia coli B to the antibacterial activity of silver ions was measured in terms of the initial inhibitory concentration, complete inhibitory concentration, postagent effect for bacteriostatic susceptibility, minimum bactericidal concentration, maximum tolerant concentration, and log killing time for bactericidal activity. At a concentration of 9.45 μM and an inoculum size of 10 CFU ml, silver caused growth delay of E. coli; at a concentration of 18.90 μM, silver completely inhibited bacterial growth. Prolonged postagent effects ranged between 1.5 and 12 h at 0.75 x the initial inhibitory concentration, 1.0 x the initial inhibitory concentration, and 1.5 x the initial inhibitory concentration of the silver ion. One log-unit of viable bacterial population size was lost every 30 min at the minimum bactericidal concentration of the silver ion. Silver tolerance was determined as 20 times the initial inhibitory concentration with 48 h of exposure. This study presents an evaluative model as a reference for the quantitative analysis of the susceptibility of bacteria to silver ions. © Rapid Science 1998.

Neuroanatomical correlates of cognitive aging: Evidence from structural magnetic resonance imaging.

Abstract: To examine putative brain substrates of cognitive functions differentially affected by age the authors measured the volume of cortical regions and performance on tests of executive functions, working memory, explicit memory, and priming in healthy adults (18-77 years old). The results indicate that shrinkage of the prefrontal cortex mediates age-related increases in perseveration. The volume of visual processing areas predicted performance on nonverbal working memory tasks. Contrary to the hypotheses, in the examined age range, the volume of limbic structures was unrelated to any of the cognitive functions: verbal working memory. verbal explicit memory, and verbal priming were independent of cortical volumes. Nevertheless, among the participants aged above 60, reduction in the volume of limbic structures predicted declines in explicit memory. Chronological age adversely influenced all cognitive indices, although its effects on priming were only indirect, mediated by declines in verbal working memory.

Perfectionism, the impostor phenomenon and psychological adjustment in medical, dental, nursing and pharmacy students

Abstract: Extensive attention has been paid over the past three decades to the stressors involved in training in the health professions. Although empirical studies have identified demographic subgroups of students most likely to become distressed during training, less research has been carried out to evaluate the impact of students' personality characteristics on their adjustment. Severe perfectionism is one such personality trait that has been shown to increase the risk for anxiety and depressive disorders in other populations. Another set of personality traits linked to increased psychological problems has been labelled the 'impostor phenomenon', which occurs when high achieving individuals chronically question their abilities and fear that others will discover them to be intellectual frauds. Both perfectionism and the impostor phenomenon would seem to be pertinent factors in the adjustment of health professional students; however, these character traits have not been empirically examined in this population. In the present study psychological distress, perfectionism and impostor feelings were assessed in 477 medical, dental, nursing and pharmacy students. Consistent with previous reports, the results showed that a higher than expected percentage of students (27.5%) were currently experiencing psychiatric levels of distress. Strong associations were found between current psychological distress, perfectionism and impostor feelings within each programme and these character traits were stronger predictors of psychological adjustment than most of the demographic variables associated previously with distress in health professional students. Implications for future research, limitations of this study and clinical recommendations are discussed.

Effects of creatine supplementation on body composition, strength, and sprint performance

Abstract: Purpose:To determine the effects of 28 d of creatine supplementation during training on body composition, strength, sprint performance, and hematological profiles.Methods:In a double-blind and randomized manner, 25 NCAA division IA football players were matched-paired and assigned to supplem

The causes, phenomenology, and consequences of hurt feelings

Abstract: One hundred sixty-four participants recounted situations in which their feelings had been hurt (victim accounts) or in which they had hurt another person's feelings (perpetrator accounts) and then completed a questionnaire. Hurt feelings were precipitated by events that connoted relational devaluation, and the victims' distress correlated strongly with feelings of rejection. Victims were typically hurt by people whom they knew well, suggesting that familiarity or closeness played a role. Analyses of the subjective experience revealed that hurt feelings are characterized by undifferentiated negative affect that is often accompanied by emotions such as anxiety and hostility. Victims' responses to the event were related to their attributions for the perpetrators' actions, and hurtful episodes typically had negative repercussions for the relationships between perpetrators and victims.

The Influence of Family on the Family Business Succession Process: a Multi-Generational Perspective:

Abstract: The present study develops a process model of succession involving steps undertaken to prepare the family business for succession. The model examined multiple spheres of influence, including indivi...

Are tannins a double-edged sword in biology and health?

Abstract: Vegetable tannins are water-soluble polyphenols that are present in many plant foods. They can be divided into hydrolysable and condensed tannins. Tannins are considered nutritionally undesirable because they precipitate proteins, inhibit digestive enzymes and affect the utilization of vitamins and minerals. Tannin components have also been implicated in the high levels of cheek and oesophageal cancers in certain regions of the world. However, many tannin molecules have been reported to reduce the mutagenicity of a number of mutagens. Tannins were also reported to have anticarcinogenic activity. The growth of fungi, bacteria, and viruses has been inhibited by tannins. Tannins in food plants serve as a natural defence mechanism against microbial infections. Thus, tannins can theoretically serve as natural regulators of the microbial population in different habitats including the human gastrointestinal tract. Tannins have also been reported to produce other physiological effects such as immune response, hepatotoxicity and lipid metabolism. Ingestion of large quantities of tannins may result in adverse health effects. However, the intake of a small quantity of the right kind of tannins may be beneficial to human health.

Oscillation in ergodic theory

Abstract: In this paper we establish a variety of square function inequalities and study other operators which measure the oscillation of a sequence of ergodic averages. These results imply the pointwise ergodic theorem and give additional information such as control of the number of upcrossings of the ergodic averages. Related results for differentiation and for the connection between differentiation operators and the dyadic martingale are also established.

Investment opportunities and market reaction to capital expenditure decisions

Abstract: In this study, we argue that share price reaction to a firm's capital expenditure decisions depends critically on the market's assessment of the quality of its investment opportunities. We postulate that announcements of increases (decreases) in capital expenditures positively (negatively) affect the stock prices of firms with valuable investment opportunities. Contrarily, we predict that announcements of increases (decreases) in capital spending negatively (positively) affect the share prices of firms without such opportunities. Our empirical results are generally consistent with these predictions. Overall, empirical evidence supports our conjecture that it is the quality of the firm's investment opportunities rather than its industry affiliation which determines the share price reaction to its capital expenditure decisions.

Stability and continuity of child-caregiver and child-peer relationships

Abstract: We examined the relationship quality of 55 (27 girls) 9-year-old children with their mothers, teachers, and friends as rated by teachers and by the children themselves. The goal of this longitudinal study was to examine stability and continuity in the quality of children's relationships between infancy and 9 years of age. At age 9, children's perception of their relationships with their teachers was associated with their current teachers' ratings of their relationships with the children. Children's perceptions of their relationships with their mothers were consistent with earlier ratings of attachment security. Children's perceptions of their relationships with teachers were predicted by the quality of their attachment relationships with their first teachers. Children's perceptions of their friendship quality was predicted by preschool teacher ratings of friendship quality and the quality of their attachment relationships with their first teachers.

Differential aging of the human striatum: a prospective MR imaging study.

Abstract: Background and purpose Advancing age is associated with declines in motor function; understanding age-related changes in the basal ganglia, therefore, is imperative for comprehension of such functional changes. The purpose of this study was to examine the age, sex, and hemispheric differences in volume of the caudate nucleus, the putamen, and the globus pallidus. Methods In a sample of 148 healthy right-handed adults (18-77 years old) with no evidence of age-related motor disorders, we estimated the volume of the head of the caudate nucleus, the putamen, and the globus pallidus from MR images. Results The analyses revealed bilateral age-related shrinkage of the head of the caudate nucleus and the putamen in both sexes. In men, the age-related shrinkage of the caudate was stronger on the left, whereas, in women, the opposite trend was evident. In both sexes, age-related shrinkage of the right putamen was greater than of its left counterpart. The mild bilateral age-related shrinkage of the globus pallidus was observed only in men. In both sexes, we observed significant rightward asymmetry in the putamen, significant leftward asymmetry in the caudate, and no asymmetry in the globus pallidus. Conclusions Bilateral age-related shrinkage of the neostriatum is found in healthy adults. The shrinkage of the globus pallidus is less pronounced and may be restricted to men only.

A developmental approach to the examination of friendship in leader-follower relationships

Abstract: A developmental approach to the examination of the leader-follower relationship offers further insight into how the relationship evolves over time and the extent to which the presence of friendship contributes to effective versus ineffective working relationships. According to Graen and Uhl-Bien (1995), the development of a leader-member exchange relationship “is based on the characteristics of the working relationship as opposed to a personal or friendship relationship” (p. 237). This article provides a developmental model of the leader-follower relationship that incorporates both the literature on friendship formation from the field of social psychology and the approach to leadership represented by the leadermember exchange (LMX) model. Propositions and research questions are presented, as are implications for future research.

Pituitary-adrenal-gonadal responses to high-intensity resistance exercise overtraining

Abstract: Weight-trained men [OT ; n = 11; age = 22.0 ± 0.9 (SE) yr] resistance trained daily at 100% one-repetition maximum (1-RM) intensity for 2 wk, resulting in 1-RM strength decrements and in an overtra...

Glutathione therapy: from prodrugs to genes.

Abstract: Glutathione (GSH; L-gamma-glutamyl-L-cysteineglycine) is found in almost all mammalian cells, and liver has very high intracellular levels of GSH. It has many cellular functions, such as being a coenzyme, maintaining thiol/disulfide status, protection against toxic compounds and oxidative stress. GSH levels have been reported to be low in a number of pathological conditions; thus methods for increasing GSH levels are desirable. GSH may be increased by supplying its amino acid precursor cysteine, in the form of prodrugs, such as N-acetylcysteine (NAC) and 2-oxothiazolidine-4-carboxylate (OTC). It may also be increased by giving gamma-glutamylcysteine, a dipeptide precursor GSH monoester and GSH diester are effective GSH delivery drugs. Such compounds may be therapeutically useful. Gene therapy may be useful for longer term therapy of GSH deficiency.

Differential Effects of Age and Sex on the Cerebellar Hemispheres and the Vermis: A Prospective MR Study

Abstract: PURPOSE The purpose of this study was to determine the effects of age and sex on the size of the cerebellar hemispheres, the cerebellar vermis, and the pons in healthy adults. METHODS We estimated the volumes of the cerebellar hemispheres (excluding the vermis and the peduncles), the cross-sectional area of the vermis, and the cross-sectional area of the ventral pons from MR images obtained in 146 healthy volunteers, 18 to 77 years old. RESULTS We found a mild but significant age-related reduction in the volume of the cerebellar hemispheres and in the total area of the cerebellar vermis; however, the analysis of age trends in the vermian lobules revealed differential age-related declines. The areas of lobules VI and VII and of the posterior vermian lobules (VIII-X) declined significantly with age, whereas the anterior vermis (I-V) showed no significant age-related shrinkage. The volume of the cerebellar hemispheres (especially the right) and the area of the anterior vermis were greater in men, even after adjustment for height. Neither age nor sex affected the area of the ventral pons. CONCLUSIONS Normal aging of the cerebellum is associated with selective regional shrinkage. The cerebellar hemispheres and the area of the anterior vermis may be larger in men than in women regardless of differences in body size.

Reliability and Efficiency of a DNA-Based Computation

Abstract: DNA-based computing uses the tendency of nucleotide bases to bind (hybridize) in preferred combinations to do computation. Depending on reaction conditions, oligonucleotides can bind despite noncomplementary base pairs. These mismatched hybridizations are a source of false positives and negatives, which limit the efficiency and scalability of DNA-based computing. The ability of specific base sequences to support error-tolerant Adleman-style computation is analyzed, and criteria are proposed to increase reliability and efficiency. A method is given to calculate reaction conditions from estimates of DNA melting.

The prospective relationships between smoking and weight in a young, biracial cohort: the Coronary Artery Risk Development in Young Adults Study.

Abstract: This study examined the relationship between smoking status and weight change from baseline to Year 7 in a large biracial cohort, the Coronary Artery Risk Development in Young Adults study. Unadjusted for covariates, only male smokers weighed less than nonsmokers, with no effect among women. Adjusted for covariates, male and female smokers weighed less than nonsmokers at baseline, adjusted for age, total energy intake, alcohol intake, and physical fitness. Over the 7-year follow-up, all smoking status groups gained weight, including continuous smokers and initiators. Weight gain was greatest among those who quit smoking. Weight gain attributable to smoking cessation was 4.2 kg for Whites and 6.6 kg for Blacks. Smoking had a small weight-attenuating effect on Blacks. No such effects, however, were observed among Whites. These results suggest, at least in younger smokers, that smoking has minimal impact on body weight.