The distribution and metabolism of creatine in the rat testis: In vivo and in vitro effects of testicular toxicants

Early work in this laboratory has shown that after testicular damage is induced in the rat there is an increase in the excretion of creatine in the urine. The aim of this project was to examine the distribution and metabolism of creatine within the rat testis, and to assess urinary creatine excretion as an index of testicular damage. Groups of rats were administered single doses of various cell-specific testicular toxicants: a germ cell toxicant (methoxyacetic acid, MAA), one of two Sertoli cell toxicants (di-n-pentyl phthalate, DPP; 1,3-dinitrobenzene, 1,3-DNB), or a Leydig cell toxicant (ethane-1,2-dimethane sulphonate, EDS). Urinary creatine and creatinine levels were monitored over the following 48 h, after which time the testes were removed, weighed and, after processing, sections were examined by light microscopy. All four treatments resulted in reductions in relative testis weight and produced morphological changes similar to those which have been widely reported in the literature. In addition, MAA, DPP and 1,3-DNB all caused large, transient elevations in urinary creatine excretion and the urinary creatine:creatinine ratio within 24 h. EDS had no such effect. It is inferred from these observations that creatine is associated with the seminiferous epithelium, and may represent a marker for damage to these cells in vivo. The distribution of creatine within the seminiferous epithelium was examined by the use of Sertoli and germ cells isolated from the testes of 4 week old rats. Both cell populations were found to contain creatine and N-phosphorylcreatine (PCr) pools, and to express creatine phosphoryltransferase (CPT) activity. Isolated seminiferous tubules synthesised creatine, and its biosynthetic precursor, guanidinoacetic acid (GAA), from L-arginine as determined by radio-metabolism studies using L-[guanidino-14C]arginine. A crude interstitial cell preparation synthesised neither creatine nor GAA. Cultured Sertoli cells incorporated radioactivity from both L-[guanidino-14C]arginine and [1-14C]glycine into creatine and GAA. Therefore, Sertoli cells have the capacity to carry out both stages of creatine synthesis; transamidination between arginine and glycine, with subsequent methylation of GAA to creatine. Germ cells did not exhibit this activity. Cultured Sertoli cells, maintained in a defined medium, secreted creatine into the overlying incubation medium, in a manner which was linear with time over at least 6 h, but which reached a plateau within 24 h. The secretion of creatine over 24 h was stimulated both by physiological and toxicological modulators of Sertoli cell function. Stimulation of creatine secretion by follicle-stimulating hormone (FSH) and N6,O-2'-dibutyl adenosine 3',5'-cyclic monophosphate (dbcAMP) was enhanced by the inhibition of adenosine 3',5'-cyclic monophosphate phosphodiesterase (cAMP PDE), indicating that creatine secretion is under the influence of intracellular cAMP levels. The secretion of creatine by cultured Sertoli cells, incubated over 4 h in BBSS, was independent of exogenous L-glutamine. However, the dbcAMP-induced stimulation of creatine secretion was dependent upon the presence of L-glutamine in the incubation medium, suggesting that increases in creatine secretion may occur as a consequence of stimulated glutamine oxidation. Isolated germ cells sequestered [1-14C]creatine in a time-dependent manner, which was linear over at least 3 h, by a two component process. One component had a high affinity for creatine (Km = 25 μM), was inhibited both at low temperature and by the absence of sodium ions from the medium, and probably represents an active uptake system. The other component, which had a low affinity for creatine and was independent of temperature and sodium, probably represents passive diffusion. It is concluded that an intercellular pathway for creatine metabolism may exist within the seminiferous epithelium of the rat, by which creatine is synthesised and secreted by the Sertoli cells and is taken up by the germ cells from the interstitial milieu. Creatine is phosphorylated within both the Sertoli and germ cells, but its role is as yet unclear

Evolving Combinational Logic Circuits Using a Hybrid Quantum Evolution and Particle Swarm Inspired Algorithm

An algorithm inspired from quantum evolution and particle swarm optimization is used to evolve combinational logic circuits. This algorithm uses the framework of the local version of particle swarm optimizations with quantum evolutionary algorithms, and integer encoding. A multi-objective fitness function is used to evolve the digital circuits in order to obtain a variety of feasible circuits with minimal number of gates in the design. A comparative study indicates the superior performance of the hybrid quantum evolution-particle swarm inspired algorithm over the particle swarm and other evolutionary algorithms (such as genetic algorithms) independently

Dicotyledonous rosettes of eastern Nebraska: Descriptions and key.

The purpose of this study is to provide descriptions of keys to the identification for the dicotyledonous rosettes of eastern Nebraska. Rosettes are defined as herbaceous, terrestrial, acaulescent cluster of leaves. Vegetative descriptions are provided for 113 species pf 56 genera. A key to the species, based on the descriptions, is provided for identification of the taxa. Field collections were made from October 1988 through July 1990, with most specimens collected from August through November 1989. Specimens were pressed and dried using commonly accepted herbarium techniques. Voucher specimens are deposited at the University of Nebraska at Omaha Herbarium (OMA). Rosettes were identified from personal experience, by growing seeds or transplanted rosettes in a greenhouse or by comparison and association with mature plants found growing with the rosettes in the field. Descriptions are based on the characteristics obtained from the pressed and dried specimens and supplemented by description from field notes on the fresh materials. Characteristics from specimens include leaf shape, leaf size, marginal configuration, surface vestiture, venation pattern, and subterranean morphology. Characteristics from field notes include distribution, habitat, odor, and the presence of latex

The Perceived Effects of the Rapid Rise of Hispanic English Limited Language Learners on the School Systems of Northeast Tennessee.

This study examined the rapid rise of the number of ELL/ Hispanic learners who are enrolling in the public school systems of Northeast Tennessee. The purpose of the study was to determine the effect that the rapid rise of ELL/Hispanic learners was having on these school systems. The approach to the study was a mixed-methods approach. Data were collected from respondents using a survey instrument that included both Likert-type responses and short answer questions. The population of this study were the 132 building-level principals of the 17 public school districts located in the First Congressional District of Northeast Tennessee. There were 81 survey responses received from the participants for a percentage of 61.4. Descriptive statistics and frequencies were used to analyze the quantitative portion of the survey using the Statistical Package of the Social Sciences program designed to analyze and display data. Qualitative data were analyzed using the cut-and-put-in-the-folder method suggested by Bogdan and Biklen (1998, p. 186). The findings of the qualitative section of the study revealed that principals were concerned about cultural differences and ways to encourage parental involvement at their children\u27s school. The communication barrier was mentioned as the most common barrier at their particular schools. Principals were concerned with the increasing pressure concerning standardized testing and adequate yearly progress. They also stated that the testing process was unfair to ELL/Hispanic students. Attendance and discipline were issues that principals stated that ELL/Hispanic students required no more of their time than did non-ELL/Hispanic students. The quantitative data revealed that principals with a substantial enrollment of 5% or more ELL/Hispanic students in their building reported they do not have an adequate number of translators and they prefer a pull-out program versus a replacement program. The findings also revealed a large neutral response from principals to the Likert-type items. This may be because these principals had few or no ELL/Hispanic students enrolled at their school

Evolving Combinational Logic Circuits Using a Hybrid Quantum Evolution and Particle Swarm Inspired Algorithm

In this paper, an algorithm inspired from quantum evolution and particle swarm to evolve combinational logic circuits is presented. This algorithm uses the framework of the local version of particle swarm optimization with quantum evolutionary algorithms, and integer encoding. A multi-objective fitness function is used to evolve the combinational logic circuits in order obtain feasible circuits with minimal number of gates in the design. A comparative study indicates the superior performance of the hybrid quantum evolution-particle swarm inspired algorithm over the particle swarm and other evolutionary algorithms (such as genetic algorithms) independently

Empirical Study of an Unconstrained Modified Particle Swarm Optimization

In this paper, an unconstrained modified particle swarm optimization (UMPSO) algorithm is introduced and studied empirically. Four well known benchmark functions, with asymmetric initial position values, are used as testing functions for the UMPSO algorithm. The UMPSO is a variation of the canonical PSO in which the velocity and position is unconstrained, an additional strategic component is added, and the social component term has been modified. The strategy component is used instead of varying parameters or mutation to enhance diversity in the swarm during the search. The UMPSO algorithm is then compared to results obtained from the constrained canonical PSO (CPSO) and the unconstrained canonical PSO (UPSO). The results show that UMPSO algorithm with no maximum velocity and position, and no minimum velocity and position value that performs better than the CPSO and the UPSO for the Sphere, Rosenbrock, Rastrigrin, and Griewank benchmark functions

Interpersonal Skills in Aviation: Applications and Development

The purpose of this paper is to highlight the critical role that interpersonal skills play in the aviation environment. Many volumes have been written on the matter and it is not our intention here to review every research endeavour in interpersonal skills and aviation but rather to provide an overview of some of the more important research, drawing out the implications for aviation management. The paper is organized in the following manner: We first examine what interpersonal skills are and why they are important in aviation. This is followed by an examination of the literature on interpersonal skills in selection (pilots, air traffic controllers), which in turn is followed by interpersonal skills and training, especially in Crew Resource Management (CRM). The paper concludes with practical suggestions regarding interpersonal skill development

Approaches to Learning: Relationships with Pilot Performance

Using a sample of 62 trainee pilots, this study aimed to examine the relationships between approaches to learning (Surface, Deep, Achieving) and performance in ground school topics of perceived differing degrees of difficulty and also performance in the aeroplane as measured by hours taken to fly solo. Significant negative relationships were found between Surface Approach scores and all ground school topics. For time taken to fly the aeroplane without an instructor, Deep scores showed a significant negative relationship. Achieving Approach scores played little role in the findings

A Comparative Analysis of Airline Pilots’ Approaches to Learning

This paper reports a study investigating approaches to learning (deep, surface, achieving) by airline pilots. Three hundred and forty-six respondents from five international airlines and an institute completed the Pilot Learning Process Questionnaire (PLPQ). The results showed a general tendency for surface scores to be substantially lower than deep and achieving scores, with greatest variability among the carriers on the achieving scale. The European carrier was implicated in all post hoc analyses conducted and one Pacific Rim carrier\u27s profile showed significant differences from other airlines. The results are discussed in terms of cultural, training/rewards, and tenure factors. Implications for pilot training and selection are noted