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PubMed1996

Choosing plants to be grown in a Controlled Environment Life Support System (CELSS) based upon attractive vegetarian diets.

Space explorers on the Moon, Mars, or even in a space craft might grow plants in a CELSS to remove CO2 and provide O2 and food. Selection of crops to be studied has been rather arbitrary but should be based on plants that can provide a balanced and attractive, mostly vegetarian diet. Additional selection criteria include ease of growth in artificial environments and sufficient variety provided over long intervals. This article is based on a workshop convened to study vegetarian diets for use in a CELSS. Participants included nutritional scientists, practicing vegetarians, and interested employees of the Johnson Space Center. It was concluded that diets meeting the criteria could be formulated, and a list of suitable crops was compiled.

Crops, Agricultural↗
PubMed2005

Development of a clinical static and dynamic standing balance measurement tool appropriate for use in adolescents.

BACKGROUND AND PURPOSE: There is a need in sports medicine for a static and dynamic standing balance measure to quantify balance ability in adolescents. The purposes of this study were to determine the test-retest reliability of timed static (eyes open) and dynamic (eyes open and eyes closed) unipedal balance measurements and to examine factors associated with balance. SUBJECTS: Adolescents (n=123) were randomly selected from 10 Calgary high schools. METHODS: This study used a repeated-measures design. One rater measured unipedal standing balance, including timed eyes-closed static (ECS), eyes-open dynamic (EOD), and eyes-closed dynamic (ECD) balance at baseline and 1 week later. Dynamic balance was measured on a foam surface. Reliability was examined using both intraclass correlation coefficients (ICCs) and Bland and Altman statistical techniques. Multiple linear regressions were used to examine other potentially influencing factors. RESULTS: Based on ICCs, test-retest reliability was adequate for ECS, EOD, and ECD balance (ICC=.69, .59, and .46, respectively). The results of Bland and Altman methods, however, suggest that caution is required in interpreting reliability based on ICCs alone. Although both ECS balance and ECD balance appear to demonstrate adequate test-retest reliability by ICC, Bland and Altman methods of agreement demonstrate sufficient reliability for ECD balance only. Thirty percent of the subjects reached the 180-second maximum on EOD balance, suggesting that this test is not appropriate for use in this population. Balance ability (ECS and ECD) was better in adolescents with no past history of lower-extremity injury. DISCUSSION AND CONCLUSION: Timed ECD balance is an appropriate and reliable clinical measurement for use in adolescents and is influenced by previous injury.

Adolescent↗
PubMed2005

Impact of genetic selection on management of boar replacement.

Boars in an artificial insemination centre have been selected for their superior genetic potential, with 'superior' being defined as having traits the customer wants transmitted to his herd. The ability to meet the customers' needs depends on the heritability of the trait, the geneticist's success in devising a selection scheme for the trait in balance with other economically important traits, and the boar's ability to produce sperm that can fertilise oocytes. Genetic evaluation research over the past 20 years has greatly increased the number of traits for which a boar can be selected: currently in the Canadian national program, these include age at 100 kg, backfat at 100 kg, feed efficiency, lean yield and litter size. In the near future, traits that are very likely to be added to this selection list include piglet survival, marbling, loin eye area and structure traits. In Canada, sires are ranked on two estimated breeding value (EBV) indices; one, focused on development of terminal sire lines, is based on the growth and yield traits and another, primarily focused on maternal line development, de-emphasises these traits and incorporates litter size. Boars that are in Canadian AI centres because of their excellent growth traits are typically in the top 5-10% of the national population for terminal sire line index, but they may be only average or substandard for litter size. Conversely, boars selected to be in the top 5-10% for conveying such reproductive traits as litter size may only be in the top 33% for growth traits. The more offspring from a superior boar in either of these indices, the faster the population average for the trait improves. The original sire gets knocked out of the elite group, is culled and replaced by a higher ranked young boar from the now improved general population. Although genetic superiority should govern an AI centre's selection and culling of boars, decision-making in real life is seldom that simple. Selection criteria may be contradictory as above, or a boar with truly superior traits may be excluded because a newly-developed molecular genetics test determines he carries an undesirable gene such as PSS, RN or others being developed. Selection for terminal sire or maternal line traits can ignore important practical factors that affect an AI centre--boars with superior genetics may not produce good semen because skeletal or penile problems prevent ejaculation, or because sperm production is poor due to a genetic flaw, disease, or some other cause. Interestingly, selection pressure for one trait may inadvertently select for a trait that is linked but whose linkage is unrecognised, and such unintentionally selected genes could benefit, harm, or have no effect on production traits. An AI centre serving a variety of customers must select boars in anticipation of their customers' needs (including new, foreign and niche markets). A centre should also review its genetic evaluation results and progeny records, both to critique its own selection success and to try to detect unexpected linkages. Finally, an AI centre needs to predict its own future, selecting not just for production traits for the swine producer, but also for factors that enhance the centre's efficiency including boar conformation and temperament, and sperm quantity, quality and hardiness. Can we select for efficiency? Our colleagues in dairy cattle AI evaluate bull performance--should the swine industry consider evaluation of male fertility traits?

Animals↗
PubMed1976

[Dynamics of population genetics parameters and their statistical during assessment selection for quantitative characters. I. An additive model. One character].

The selection for a single additively inherited quantitative character is studied using computer models of 3 types: 1) all the individuals had the same viability, and the paratypic deviation does not depend on their genotype; 2) differential viability of genotypes is taken into account with respect to a number of heterozygous loci; 3) differential paratypic deviation is estimated, it is introduced like viability in the model 2. Two types of trancation selection, stabilizing and directed, under the selection coefficient of approximately 0.5 are studied. There are studied dynamics of genotypic (omega2gamma) and phenotypic (omega2phi) variances, the heritability index and it estimates (for the correlation progeny-parent--rho; for the regression progeny-parent--b; for half-sibses--v), and the non-equilibrium of a population for the models. The number of generation was 10; the population number in every generation was 200; the number of loci in the main experiment was 10.h2 values were calculated in the progeny before selection (p1, b1, v1) and after selection (p2, b2, v2). It is shown that stabilizing selection results in the formation of balanced gene complexes; the rate of decreasing omega2phi depends on the genetic length of a chromosome region in which genes, determining the character, are located, and not on the number of genes. The distribution of a character under directed selection depends on the type of the model. p2, b2, and v2 values are the worst. The best is the b1 value. It is concluded that the problem of predicting the selection effect using statistical estimates of heretability is connected with the problem of investigation of population heterogeneity and integrating their genetical structure.

Computers↗
PubMed1999

Balance and muscular strength in normal children aged 9-12 years.

The purposes of this study were two fold. The first was to determine the effects of several independent variables on balance, and also on two muscular strength (dynamic and static) measurements respectively. The second purpose was to examine the relationship among the balance and the muscular strengths. Ninety-nine healthy children (58 boys and 41 girls) ranging in age from 9.6 to 12.7 years participated in this study. The subjects were selected from the 4th, 5th and 6th grades of an elementary school in Kaohsiung City. To assess balance, children were administered subtest 2 of Bruininks Oseretsky Test of Motor Proficiency (BOTMP). Dynamic strength was measured with the subtest 4 of the BOTMP. Static strength was measured quantitatively by "semi-squat two-hand lift". The Force Evaluation and Testing System was used for this testing. Height and weight measurements were obtained on each subject. The independent effects of variables on balance score and the two muscular strengths were assessed by stepwise multiple-regression analysis. The results revealed weight and dynamic strength were the effective predictors on estimating balance score. Gender and weight were found as important variables contributing in static load, whereas gender, weight, height and balance score were selected for significantly predicting dynamic strength score. Spearman correlation analysis revealed significant positive correlations between balance and dynamic strength and also between dynamic strength and static strength. The correlation analysis also showed a significant negative correlation between balance and static strength. Detailed implications of the results in the present study are discussed.

Child↗
PubMed2005

How should we inform women at higher risk of breast cancer about tamoxifen? An approach with a decision guide.

BACKGROUND: Tamoxifen has been shown to reduce the incidence of invasive breast cancer in women at higher risk. Translating these research results to clinical practice is challenging. Our objective was to develop and evaluate a decision-making guide and process that can be used in clinical practice to inform eligible women of chemoprevention with tamoxifen. METHODS: A decision guide explaining the benefits and risks of tamoxifen was developed with input from health care professionals and two focus groups of women both with and without cancer. Following consent, 51 eligible women presenting to a multi-disciplinary diagnostic facility for breast problems were given the decision guide/questionnaire to read, fill out and return by mail. Women with further questions or wanting to take tamoxifen were encouraged to re-contact their physicians. RESULTS: Atypia was seen in 60% of subjects. Median 5-year Gail risk was 3.7 (range 1.7-9.4). Only 6 (11.8% 95% CI = 2.9, 20.6%) women reported they would like to take tamoxifen while 6 (11.8% 95% CI = 2.9, 20.6%) remained uncertain. CONCLUSION: We have developed a decision-making guide and process that is acceptable to providers and women to identify and inform women at higher risk of breast cancer with regard to chemoprevention with tamoxifen. Few women in this select group, when provided with a balanced decision guide, wished to pursue chemoprevention with tamoxifen.

Breast Neoplasms↗
PubMedDate not supplied

Assessment of selected co-stimulatory, adhesion and activatory molecules and cytokines of Th(1)/Th(2) balance in acute lymphoblastic leukemia in children.

INTRODUCTION: Recent years have seen a rise in the importance of cytokine production and co-stimulatory/activatory molecule expression in the immune response in leukemia. The aim of our study was to assess the function of T lymphocytes in children with acute lymphoblastic leukemia (ALL) during remission induction based on selected cytokine and co-stimulatory/activatory molecule expression. MATERIAL/METHODS: The study group consisted of 50 children with ALL (B cell precursor). Peripheral blood samples were taken before treatment (day 0), after the prednisone prophase (day 8), and during (day 15) and after (day 33) remission induction. The percentages of T cells with interferon (IFN)-gamma (Th(1)), interleukin (IL)-4 (Th(2)) and IL-2 receptor (IL-2R), CD28, CTLA-4, CD38, ICAM-1, and HLA-DR expression were assessed by tricolor flow cytometry. RESULTS: At the time of diagnosis we noted higher percentages of T cells with adhesion molecule ICAM-1, activation molecule CD38 expression, and an increased population of Th(2 )cells (IL-4) compared with the control group. During and after remission induction we observed a decreased population of CD38(+) T cells, elevated percentages of helper T lymphocytes with IL-2R expression, and a rise in helper T lymphocytes producing IFN-gamma (Th(1)). During fever/infection, higher levels of activated T lymphocytes (CD4(+)HLA-DR(+), CD8(+)HLA-DR(+)), a rise in Th1, and no change in Th(2 )populations were observed. CONCLUSIONS: The results suggest T cell activation and Th(2 )predominance at the time of diagnosis and during remission induction in ALL in children. These results confirm the involvement of cellular immunity in the leukemic process and can be used in immune therapy in leukemia.

CD28 Antigens↗
PubMed1980

Effects of oral contraceptive agents on copper and zinc balance in young women.

Young adult women were selected from a group of volunteers on the basis of present and past use of oral contraceptive agents. Subjects were either those who had never used oral contraceptives or those who had used an agent for a minimum of two menstrual cycles. All subjects were fed diets that provided 2.02 to 2.11 mg of copper and 9.15 to 9.10 mg of zinc daily in an 18-day controlled metabolic study. Both oral contraceptive users and nonusers were in negative zinc balance and zinc excretion as not different (P > 0.05) for the groups. Oral contraceptives did not alter (P > 0.05) the metabolic balance of copper; the mean copper retention values were -0.16 mg/day for the nonusers and -0.13 mg/day for the users of oral contraceptives. As anticipated from reports in the literature, the plasma copper levels were higher (P < 0.01) in the oral contraceptive group, but the levels of zinc were not different. Although blood levels of zinc and copper are usually changed with the use of oral contraceptives, the retention of the two nutrients appears not to be affected.

Adult↗
PubMed1994

Inversion polymorphism and accumulation of lethals in selected lines of Drosophila melanogaster.

Five long-term selected lines of Drosophila melanogaster were monitored for the presence of lethals and inversions on the third chromosome for a period of nearly 100 generations after the cessation of selection. The results provide an example of the action of inversions as a trap for genes with homozygous detrimental effects in small populations. Lines polymorphic for cosmopolitan inversions In(3R)C and In(3L)P maintain linked lethal and detrimental genes in a near-balanced system. Consideration of the high selection response attained despite inversion polymorphism leads to the conclusion that extreme responses to selection can be obtained without exploiting the potential from large genomic regions.

Animals↗
PubMed1988

Remodeling of synaptic architecture during hippocampal "kindling".

The "kindling" phenomenon is associated with long-lasting facilitation of synaptic transmission. A possible mechanism of such facilitation could involve changes in the number of synaptic contacts. However, previous attempts to demonstrate a synaptic morphological alteration that could account for the long-term effects of kindling had failed, possibly due to the unavailability, at the time, of unbiased methods for synapse quantitation. Using the unbiased stereological disector technique, we estimated the number of synapses per neuron in the middle molecular layer of the hippocampal dentate gyrus in rats kindled by electrical stimulation of the medial perforant path with implanted electrodes. Unkindled but stimulated (coulombic control) and unstimulated but implanted rats served as controls. Animals were coded and killed 4 weeks after reaching the kindling criterion of five generalized seizures. The most important results were obtained when axospinous synapses with continuous or discontinuous postsynaptic densities ("nonperforated" or "perforated" synapses) were differentially analyzed. Kindling resulted in a selective loss of nonperforated synaptic contacts in contrast to preservation of perforated ones. Furthermore, the ratio of perforated to nonperforated synapses was increased by 45% or 40% in kindled rats relative to unstimulated or coulombic controls, respectively. These findings suggest that synaptic efficacy may depend on a balance of the two synaptic types; selective elimination of nonperforated synapses may augment the potency of remaining synaptic contacts, a process reminiscent of synaptic remodeling during development.

Algorithms↗
PubMed1999

The effect of mating system differences on nucleotide diversity at the phosphoglucose isomerase locus in the plant genus Leavenworthia.

To test the theoretical prediction that highly inbreeding populations should have low neutral genetic diversity relative to closely related outcrossing populations, we sequenced portions of the cytosolic phosphoglucose isomerase (PgiC) gene in the plant genus Leavenworthia, which includes both self-incompatible and inbreeding taxa. On the basis of sequences of intron 12 of this gene, the expected low diversity was seen in both populations of the selfers Leavenworthia uniflora and L. torulosa and in three highly inbreeding populations of L. crassa, while high diversity was found in self-incompatible L. stylosa, and moderate diversity in L. crassa populations with partial or complete self-incompatibility. In L. stylosa, the nucleotide diversity was strongly structured into three haplotypic classes, differing by several insertion/deletion sequences, with linkage disequilibrium between sequences of the three types in intron 12, but not in the adjacent regions. Differences between the three kinds of haplotypes are larger than between sequences of this gene region from different species. The haplotype divergence suggests the presence of a balanced polymorphism at this locus, possibly predating the split between L. stylosa and its two inbreeding sister taxa, L. uniflora and L. torulosa. It is therefore difficult to distinguish between different potential causes of the much lower sequence diversity at this locus in inbreeding than outcrossing populations. Selective sweeps during the evolution of these populations are possible, or background selection, or merely loss of a balanced polymorphism maintained by overdominance in the populations that evolved high selfing rates.

Base Sequence↗
PubMed2006

Understanding the opposition.

Current debates about sex selection start from a paradox: on the one hand, the 'liberal' argument in favour of sex selection is often thought to be sound; but on the other hand there is widespread public opposition to sex selection. So it is worth spending some time examining the arguments against sex selection. Four different types of argument are identified: (i) religious arguments; (ii) consequentialist arguments, mainly concerning disturbance to the sex ratio; (iii) arguments to the effect that sex selection involves a failure to respect the autonomy of a child; (iv) arguments to the effect that the motivation for sex selection brings with it an instrumental attitude to children not compatible with a child's need for unconditional acceptance and love. In the end the conclusion is reached that none of these arguments provide decisive arguments against the liberal thesis that sex selection ought to be permitted, especially where 'family balancing' is envisaged. In the light of this conclusion the issue of fetal sexing followed by selective feticide as a method of sex selection is discussed. It is argued that sex selection is not in general a good reason for abortion, but that this practice may become unstoppable.

Attitude↗
PubMed1997

Changing reversed-phase high performance liquid chromatography selectivity. Which variables should be tried first?

When carrying out HPLC method development, it is often necessary to vary the relative retention of the sample (values of alpha) by changing some experimental variable, e.g., solvent type, pH, etc. The choice of which variable will be most suitable for a change in selectivity depends on two conflicting goals: (a) the attainment of maximum changes in alpha for the better control of resolution and (b) the avoidance of practical problems associated with the use of a given variable to optimize selectivity. This study provides a quantitative evaluation of different variables for their effect on selectivity (alpha). Various practical problems which must be balanced against this ability of a variable to change value of alpha are also discussed. The selection of any two variables for their simultaneous use in controlling alpha is also examined.

Chromatography, High Pressure Liquid↗
PubMed2003

[Biochemistry of lifespan extension].

A review of biochemical mechanisms underlying the known approaches to extension of lifespan and/or slowing down of ageing suggests that they all modify balances between generation of active oxygen and carbonyl species and the mechanisms that protect from their damaging effects or repair their consequences. A likely common target of the geroprotector effects of antioxidants, melatonin, and antidiabetic biguanides is the mitochondrial respiratory chain. In biological species that evolved through r-selection (nematodes, fruit flies, mice, and rats), the balance between anabolic/reproductive and self-maintenance/protective functions is the most significant modifiable factor of longevity and ageing. At the molecular level, the pivot of this balance is formed by the forkhead-type transfactors, whereas at the physiological level the balance is determined by dietary calories and physical activity via mechanism in which the central role is played by insuline-like peptides and, also, growth hormone and leptin or their functional analogs. In biological species that evolved through K-selection (higher primates, particularly humans), the latter balance is less important, and the biochemical factors of aging are more refracted through the higher regulatory systems, of which the most significant are catecholaminergic mechanisms of regulation of neuroendocrine-immune interrelationships and the circulatory system. This results in a decreased geroprotector potential of calory restriction and in an increased importance of the optimal physical activity. When these conclusions are compared with demographic data, it comes out that virtually all advances in gerontology may be reduced to maxims of healthy ageing known from extreme antiquity. Under optimal socioeconomic conditions, the chances to approach the documented world record of human longevity (122 years) may be increased by (not to mention getting rid of smoking and other abuses) high physical activity, adequate nutrition enriched in fresh fruits, optimism, and timely treatment of specific diseases. The most important bottleneck in the realization of these reserves is currently the public consciousness rather than the science.

Aging↗
PubMedDate not supplied

[Selection and mutation from the theoretical information point of view--limits of the preservation of genetic information].

There is no doubt that evolution can only operate in accordance with the laws of thermodynamics. To transform this simple perception into a statement that can be quantified it is necessary to examine how the entropy (or the information content) changes by means of the two main factors of evolution: selection and mutation. In the present paper this aim was reached by using the methods of information theory. That evolution becomes possible the change of information by mutation and selection must not be negative in the long run. Consequently an upper limit for the information content of the genome must be assumed. If the evolution as a self-optimizing process gains this upper limit it reaches a dynamic equilibrium at which the increase of entropy by mutation balances the decrease of entropy by selection. In particular it was examined under which circumstances of dynamic equilibrium master-genotypes (genotypes that can preserve their specific sequence over a long time) can exist.

Biological Evolution↗
PubMed1987

Effect of specific foods, beverages, and spices on amount of ileostomy output in human subjects.

To measure the effect of various selected foods on the amount of ileal excreta, 37 metabolic balance studies were performed on seven subjects who had normal functioning ileostomies for ulcerative colitis. Although this investigation was conducted with the subjects living at home and selecting their own diet, metabolic balance techniques were carefully observed. The diet was identical in the 3-day control and 3-day experimental period except for the alteration of one aspect of the diet in the experimental period. The substances tested were those often either interdicted for or avoided by ileostomates. Only seven (five fruits, one vegetable, and prune juice) of the 37 dietary substances significantly increased the ileal effluent. Excessive water intake, alcohol beverages, fried foods, and spices did not increase ileostomy output. A small but significant loss of sodium and in some instances potassium was observed with prune juice and some fruits that statistically increased ileal output. Although a limited number of foods were studied, application of the results suggests that many dietary substances generally avoided by or interdicted for ileostomates did not significantly increase the amount of ileal excreta when objective measurements are made.

Adult↗