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PubMed1983

Role of testosterone secretion and penile reflexes in sexual behavior and sperm competition in male rats: a theoretical contribution.

A number of experiments have documented that when male rats are exposed to female rats they undergo a marked increase in the secretion of luteinizing hormone and testosterone. This response can be conditioned to other, previously neutral, stimuli associated with mating. Recent work has highlighted the remarkable sensitivity of penile reflexes to fluctuations in blood concentration of testosterone. Other work has pointed to the function of penile reflexes in seminal plug removal and deposition. It is hypothesized that penile reflexes are potentiated by the increase in testosterone that occurs in response to sexually relevant cues and that the potentiated reflexes play a role in sperm competition during multi-male mating encounters. The sperm competition centers around a male rat's ability to dislodge seminal plugs left in the vagina by other males and to deposit his own plug as tightly as possible to resist dislodgement by another.

Animals↗
PubMed2000

The genetic liability to stress and postweaning isolation have a competitive influence on behavioral organization in rats.

Rats housed in social isolation postweaning (isolates) show profound behavioral and neurobiological differences when compared to socially housed rats (socials). Fischer rats (F344) relative to Lewis rats are hyperresponsive and significantly more susceptible to stressful stimuli. This investigation tested the hypothesis that the behavioral effects of postweaning isolation are more pronounced in a strain of rats with high susceptibility to stress compared to a strain with low susceptibility to stress. Seventy male Sprague-Dawley, Lewis, and F344 rats were housed individually or in groups at weaning on Day 21 and tested on Day 85 in the Behavioral Pattern Monitor. There was no interaction between strain and postweaning isolation for measures of locomotor activity and exploratory behavior (holepoking). However, the postweaning isolation-induced increase in the frequency of repetitive straight movements, a measure of behavioral organization, was more pronounced in Lewis isolates compared to Sprague-Dawley and F344 isolates. These results do not support the hypothesis that rats with a higher susceptibility to stress show more pronounced changes in behavior following postweaning isolation; instead, increased susceptibility to stress may counteract the repetitive movement patterns induced by social isolation.

Animals↗
PubMed2004

Hematopoietic stem cells from NOD mice exhibit autonomous behavior and a competitive advantage in allogeneic recipients.

Type 1 diabetes is a systemic autoimmune disease that can be cured by transplantation of hematopoietic stem cells (HSCs) from disease-resistant donors. Nonobese diabetic (NOD) mice have a number of features that distinguish them as bone marrow transplant recipients that must be understood prior to the clinical application of chimerism to induce tolerance. In the present studies, we characterized NOD HSCs, comparing their engraftment characteristics to HSCs from disease-resistant strains. Strikingly, NOD HSCs are significantly enhanced in engraftment potential compared with HSCs from disease-resistant donors. Unlike HSCs from disease-resistant strains, they do not require graft-facilitating cells to engraft in allogeneic recipients. Additionally, they exhibit a competitive advantage when coadministered with increasing numbers of syngeneic HSCs, produce significantly more spleen colony-forming units (CFU-Ss) in vivo in allogeneic recipients, and more granulocyte macrophage-colony-forming units (CFU-GMs) in vitro compared with HSCs from disease-resistant controls. NOD HSCs also exhibit significantly enhanced chemotaxis to a stromal cell-derived factor 1 (SDF-1) gradient and adhere significantly better on primary stroma. This enhanced engraftment potential maps to the insulin-dependent diabetes locus 9 (Idd9) locus, and as such the tumor necrosis factor (TNF) receptor family as well as ski/sno genes may be involved in the mechanism underlying the autonomy of NOD HSCs. These findings may have important implications to understand the evolution of autoimmune disease and impact on potential strategies for cure.

Animals↗
PubMed1991

Regulating physician investment and referral behavior in the competitive health care marketplace of the '90s--an argument for decentralization.

Congress regulates the investment and referral practices of physicians through the federal Anti-Fraud and Abuse statute. The Anti-Fraud and Abuse statute, however, limits the ability of physicians to adapt their investment and referral practices to an increasingly competitive health care industry. In order to restrict fraudulent practices without restricting competition, the authority to regulate physician investment and referral practices should be returned to the states, who can recognize and exempt beneficial competitive practices from the reach of the applicable state statutes.

Economic Competition↗
PubMedDate not supplied

[Behavioral mechanisms of spatial competition between red wood ants (Formica aquilonia) and ground beetles (Carabidae)].

Behavioral aspects of spatial competition between red wood ants (Formica aquilonia) and six mass species of Carabidae were studied in field and laboratory experiments. We showed that red wood ants essentially influence spatial distribution of ground beetles on their common territories. Transplantation experiments suggest that in newly established ants' settlements stronger forms of interrelations arise than in old stable colony. To examine the ability of beetles to avoid collisions with ants we used two experimental techniques. In laboratory, we tested carabids ability to avoid a clash in a Y-shaped labyrinth containing an active tethered ant in one section. In field experiments we compared quantitative characteristics of movements (such as crookedness of individual trajectories, speed of movement, the time spent on stops) for beetles placed close to ants foraging routes and on ant-free plots. All beetles studied displayed a clear tendency to learn, that is, to modity their behavior in order to avoid collisions with ants. Species that exhibited best parameters of learning were closer to ants by their size and characteristic movement, namely, Pterostichus oblogopunctatus and P. magus. Beetles' stereotyped behavioral tactics can be considered universal for avoiding collisions with any subject (for instance, with an ant) of a certain size and speed of movements. A set of tactics in the labyrinth included: (1) attempts to round the ant; (2) turns away after touching the ant with antennae; (3) turns away without a contact; (4) avoidances of a dangerous section; (5) stops near the ant with the antennae hidden. Comparing pairwise difference between four species shows that beetles use species-specific preference for definite combinations of tactics. Effective learning allows carabids to penetrate into ant foraging territory and partly avoide interference competition. It seems that red wood ants are not inclined to learn to avoid collisions with competing carabid species. Instead, they recognize an "enemy's image" and selectively attack relatively small predatory carabids rather than herbivorous species. Experiments with dummy beetles suggest that ants react for several hierarchically organized key characteristics of competitors such as speed of movement, dark color, bilateral symmetry, protuberances (legs, antennae), and smell. Among "professional" groups in ant family, guards and hunters react to beetles aggressively, whereas aphid tenders ignore them. Sophisticated combination of flexible and innate behavioral patterns enables insects to share territories and interact in the mode of relatively mild, spatial, competition instead of predation. Eliciting sets of hierarchically organized features of competitors that govern adjustment of spatial distribution in insects' community enable us to integrate ideas of classic and cognitive ethology.

Animals↗
PubMed2002

[A study of school children with type A behavior pattern association of "competitiveness" and "impatience-aggression" with lifestyle-related factors].

PURPOSE: To study associations of the type A behavior pattern with the results of physical and blood examinations and data from a questionnaire on lifestyle for elementary school and junior high school students. METHODS: 277 elementary school students of 4th grade (9-10 y) and 297 junior high school students of 1st grade (12-13 y) in a community in Saitama who completed a test for the type A behavior pattern developed by Yamasaki, underwent physical and blood examinations for parameters like serum cholesterol, blood pressure, height and weight and were administered a questionnaire concerning lifestyle. RESULTS: Points of the test for a type A behavior pattern were higher in 9-10 y than in 12-13 y individuals (both sexes or boys). Factor analysis applying 17 items of the test for type A behavior as variables demonstrated two common factors; "competitiveness" and "impatience-aggression". Mean impatience-aggression scores for individuals were significantly higher in 9-10 y than in 12-13 y children; however, the competitiveness score showed no significant difference between the two groups. Higher competitiveness scores were shown by children who prefer sports or play sports after school, also in 9-10 y children not warned against excess eating or not eating slowly by their parents. Higher impatience-aggression scores were shown by children not preferring sports, not playing sports after school, eating while watching TV or reading books, and also in 9-10 y children eating until full, and in 12-13 y children not chewing foods well or who were warned of excess eating by parents. 12-13 y students having a higher atherosclerosis index showed low competitiveness and high impatience-aggression scores. CONCLUSION: By analyzing two factors included in the type A behavior pattern in school children, we found associations with lifestyle and the atherosclerosis index. The results provide a basis for further follow-up studies on the relationship between type A behavior pattern and prevention of future cardiovascular disease.

Adolescent↗
PubMed2005

A model of contagion through competition in the aggressive behaviors of elementary school students.

This article extends the work of Kellam, Ling, Merisca, Brown and Ialongo (1998) by applying a mathematical model of competition between children to peer contagion in the aggressive behaviors of elementary school students. Nonlinearity in the relationship between group aggression and individual aggression at 2-year follow-up is present. Consistent with the findings of Kellam et al. (1998), hierarchical linear modeling indicates that the relationship is statistically significant for those students whose initial parental ratings of aggressive behavior were above the sample median. In the context of competition between students, the behavior of initially aggressive students may be negatively reinforced. Lowering aggression in the school environment may therefore be the most effective way to lower the level of these students' aggressive behavior.

Aggression↗
PubMed1999

Four-year changes in college athletes' ethical value choices in sports situations.

Positive values for fairness in competition are supposed to undergird the behavior of athletes engaged in sport. Whether athletes' values actually develop over 4 years in a college that emphasizes character development is the focus of this study. Athletes' (N = 631) use of deontological ethics (Hahm, Beller & Stoll, 1989) in 21 sports value dilemmas were evaluated. At entrance, as well as near graduation, intercollegiate athletes' value scores were lower than intramural athletes' scores. Both groups' scores declined while they were in college. Individual-sport athletes had higher scores than team-sport athletes but manifested a greater decline over 4 years. The findings are consistent with other studies that show decreases in "sportsmanship orientation" and an increase in "professional" attitudes associated with participation in sport.

Age Factors↗
PubMed2004

Effects of competitor and natural organic matter characteristics on the equilibrium sorption of 1,2-dichlorobenzene in soil and shale.

The competitive sorption behaviors of 1,2-DCB in binary solute systems in four natural sorbents having natural organic matter (NOM) matrixes of different physicochemical characters were investigated in batch reactors. Specifically, the study focused on investigating how the extent of 1,2-DCB competitive sorption depends on (i) the rigidity of NOM matrixes as assessed by the efficiency of chemical oxidation and (ii) the closeness of competitor structure to that of the primary solute. The chemical oxidation and elemental composition results suggest that the shale NOM is the most reduced and condensed, the peat was the most oxidized and amorphous, and two surface soils had intermediate NOM structures. Four chlorinated benzenes and phenanthrene were used as competing solutes. All five chemicals exhibited competition against 1,2-DCB in all sorbents, including the peat, but the extent of competition varied significantly. Little difference in the extent of competition with 1,2-DCB was observed for the various chlorinated benzenes even though some were liquids and some were solids at the experimental temperature. All of the chlorobenzenes were more effective competitors than phenanthrene. The shale showed markedly different competition features from the other sorbents, with a much smaller competitive effect at a given sorbed volume of competitor. However, normalizing sorbed competitor volumes by the capacity of the adsorption domain in the Polanyi-Manes single-solute partition-adsorption model (V0) produced qualitatively similar competitive behavior for each solute; displacement of 1,2-DCB increased with increasing sorbed competitor volumes up to V0, and little additional competition occurred beyond that point. The extent of competition was positively correlated with the maximum adsorption capacity and the fraction of "hard" and "soot" carbon contents as assessed by chemical and thermal oxidation methods. These findings indicate that competition is associated with voids in the NOM structure, that these voids are likely present within the condensed ("hard" plus "soot") carbon domain, and therefore that diagenetic alteration of NOM plays a central role in determining competitive sorption characteristics for hydrophobic contaminants.

Adsorption↗
PubMed2006

Relationship between sexual behavior classifications of rams and lambs sired in a competitive breeding environment.

The objectives for this study were to 1) determine the relationship between sexual performance class and lambs sired in a competitive mating environment, and 2) determine whether the male-oriented ram test is valid. Fifteen 2- to 3-yr-old whitefaced rams classified as female-oriented, with high or low sexual performance, or classified as male-oriented were used in a multiple-sire breeding arrangement. Five groups of approximately 200 ewes each were exposed for 21 d to 3 rams per group consisting of 1 ram from each class. Rams were blocked for sexual class, and those with close genetic relationship were assigned to different pens. Genomic DNA was prepared from blood collected from 15 rams, 934 ewes, and 1,757 lambs. Up to 4 microsatellite markers were used to determine a lamb's sire. Of 884 ewes with identifiable lambs (known sires), 178 ewes had single lambs, 408 had multiples sired by 1 ram, and 298 had multiples sired by more than 1 ram. The sexual partner preference test used to identify male-oriented rams did not absolutely reflect their sexual performance during competitive breeding. In contrast to only mounting and servicing males in preference tests before breeding, male-oriented rams sired 480 lambs from 330 ewes. Serving capacity tests predicted sexual performance of high and low sexual performance rams. High performance rams impregnated more ewes (499 vs. 258; P < 0.05) and sired more lambs (756 vs. 357; P < 0.05) than did low performance rams, respectively. Low performance and male-oriented rams did not differ for ewes impregnated or lambs sired. We conclude that 1) sexual partner preference tests used to classify male-oriented rams were not absolute in reflecting their breeding performance in a competitive breeding environment; 2) serving capacity tests predicted that high performance rams would breed more ewes than low performance rams and sire more lambs than either low performance or male-oriented rams; and 3) under the conditions of this study, low performance and male-oriented rams did not have an adverse impact on the overall breeding outcome. Combined, low performance and male-oriented rams sired 81 more lambs than did high performance rams, but this required twice as many rams to obtain approximately equal breeding results. Therefore, we suggest that serving capacity tests should be used to select high performance rams, reduce number of rams with marginal sexual performance, and make decisions on ram numbers needed.

Animals↗
PubMed1999

Regulating managed care: interest group competition for control and behavioral health care.

In this essay I identify how historic patterns of competition among health care interest groups have simultaneously retained their past contours and also changed significantly as a result of the jolt created by the rise of managed care. I explain why it is that I and other executives of for-profit managed behavioral health care organizations, traditionally advocates of market-based approaches to accountability, have begun to support some versions of regulation by the national government in order to restore consumer confidence in the credibility of managed health plans. Key concepts that are addressed include notions of public accountability, control of the purse strings, consumer protections, and provider privileges.

Behavioral Medicine↗
PubMed1996

Effect of subchronic and chronic exposure to 5-hydroxytryptophan (5-HTP) on the aggressive behavior induced by food competition in undernourished dominant and submissive pigeons (Columba livia).

The acute administration of 5-HTP was reported to block in undernourished dominant pigeons the aggressive attacks induced in a submissive partner by food competition. In the present study, undernourished pigeons with previously consolidated dominance were submitted to subchronic and chronic 5-HTP treatment. Adult males (n = 28) were kept at 80% of their body weight by a restricted diet. These were divided in pairs made of a previously ranked dominant subject (total time spent in aggression higher than 200 s/20 min) and a submissive one of similar body weight (time spent in aggression between 90 and 150 s/20 min). The same pairs were exposed to a daily 20 min interaction during each experiment in an observation chamber bearing a central feeder. The time spent in aggressive behavior, feeder control behavior and eating behavior was recorded. Intratest body weight gain was also recorded. In Experiment 1, 8 pairs of pigeons were exposed to a daily trial for 4 successive days (pretreatment-scores). The dominant subjects were then injected subcutaneously, 30 min. before trials, with 7.5 mg/kg 5-HTP from day 5 to day 8 (Treatment scores). The Recovery scores were obtained through a 4-trial post-treatment schedule. In Experiment 2 different pigeons were used. The pretreatment and recovery scores were obtained according to a 16-trial schedule (16 days). Both 4-day (subchronic) and 16-day (chronic) 5-HTP treatments attenuated aggression by the dominant subjects and reduced their intra-test body weight gain but did not decrease dominance for feeder control. The recovery scores of total aggression in subchronic experiments returned to pretreatment scores. In chronic experiments, instead, the recovery scores of aggression remained lower than pretreatment scores, whereas body-weight-gain scores came back to pretreatment values. This suggests that dominant subjects submitted to chronic 5-HTP might have learned to maintain dominance and feeder control in a virtual absence of aggressive behavior.

5-Hydroxytryptophan↗