Evaluation of Drugs for Treating Obesity

Criteria for the evaluation of new drugs to treat obesity are important as guides for designing clinical trials to test these agents. These criteria must be developed in relation to the realities of obesity, which is a chronic disease associated with morbidity and mortality that is increased by visceral fat deposits. The observation that patients regain weight after stopping drug treatment for obesity argues for the proposition that drugs work only when taken and NOT that the drugs are ineffective. The analogy between the development of treatments for obesity to those for the treatment of hypertension is used to highlight potential areas for new developments. Several features of an ideal drug for the treatment of obesity are suggested. Criteria for evaluating new drugs include both primary and secondary endpoints. The primary endpoint for an anti-obesity drug should be weight loss, possibly by category of success. Losses of total body fat or visceral fat might be alternative primary endpoints. Secondary endpoints include reduction in risk factors for associated diseases and improvement in the quality of life. In trials where vigorous placebo designs including highly aggressive behavior modification or very-low-calorie diets were used, it may be difficult or impossible to detect a response to a drug.     

Psychological perspectives of ecosystem health

Behavior-based and person-based perspectives are integrated to summarize approaches for dealing with the human element of ecosystem health. Behavior is selected by its consequences, and therefore interventions are needed to decrease the natural reinforcing consequences (e.g., convenience, efficiency) of environment-destructive behaviors and to increase the reinforcing consequences of environment-protective behaviors. An ABC Model (for Activator-Behavior-Consequence) can be applied effectively to design intervention programs for benefiting the human behavior aspects of ecosystem health. However, intervention agents are needed to implement positive behavior-change techniques, and this requires people to actively care enough to emit other-directed (or altruistic) behaviors for the health of the ecosystem. Person factors which influence one's propensity to actively care include: self-esteem, belongingness, and empowerment, influenced by perceptions of self-efficacy (I can do it), personal control (I am in control), and optimism (I expect the best). Strategies are reviewed for increasing these person states or expectancies. The health of our ecosystem depends upon people changing their behaviors and attitudes regarding the environment. Behavior-based psychology offers the technology for changing behaviors and attitudes in desirable directions; person-based psychology offers the states or expectancies needed in people to increase their willingness to actively care for the environment. By applying the theory and principles from these subdisciplines of applied psychology, the critical human element of our ecosystem can be accounted for and managed effectively.     

Temperature-dependent sex determination in reptiles: Proximate mechanisms,ultimate outcomes,and practical applications

In many egg-laying reptiles, the incubation temperature of the egg determines the sex of the offspring, a process known as temperature-dependent sex determination (TSD). In TSD sex determination is an “all or none” process and intersexes are rarely formed. How is the external signal of temperature transduced into a genetic signal that determines gonadal sex and channels sexual development? Studies with the red-eared slider turtle have focused on the physiological, biochemical, and molecular cascades initiated by the temperature signal. Both male and female development are active processes—rather than the crganized/default system characteristic of vertebrates with genotypic sex determination—that require simultaneous activation and suppression of testis- and ovary-determining cascades for normal sex determination. It appears that temperature accomplishes this end by acting on genes encoaing for steroidogenic enzymes and steroid hormone receptors and modifying the endocrine microenvironment in the embryo. The temperature experienced in development also has long-term functional outcomes in addition to sex determination. Research with the leopard gecko indicates that incubation temperature as well as steroid hormones serve as organizers in shaping the adult phenotype, with temperature modulating sex hormone action in sexual differentiation. Finally, practical applications of this research have emerged for the conservation and restoration of endangered egg-laying reptiles as well as the embryonic development of reptiles as biomarkers to monitor the estrogenic effects of common environmental contaminants. © 1994 Wiley-Liss, Inc.     

Sexual differentiation of brain and behavior in the zebra finch: Critical periods for effects of early estrogen treatment

In order to determine the critical period(s) during which estrogen alters sexually dimorphic behavior and neuroanatomy in zebra finches (Poephila guttata), nestlings were injected daily 20 μg estradiol benzoate (EB) during posthatching week 1, week 2, week 3, or weeks 1, 2, and 3. At 7 months of age, birds were implanted with testosterone propionate and tested with female partners for singing, dancing, and copulatory mounting. Brains were subsequently processed for morphometry, and the volumes of the song system nuclei HVC, area X, and RA and the soma sizes and densities of neurons in RA were determined. Males given EB during week 1 failed to mount. Females given EB during week 1 were fully masculinized with respect to dancing and RA neuron soma size and density, and were partially masculinized with respect to song nuclei volumes and singing. Treatment beginning after week 1 was ineffective or less effective for all measures. Only for RA neuron measures was treatment for all three weeks more effective than week 1 treatment. Thus the first post-hatching week is the most influential period of those tested for effects of exogenous estrogen on sexual differentiation in this species, and is a period during which both masculinization of females and demasculinization of males is possible. 1994 John Wiley & Sons, Inc.     

Neurotoxic mechanisms of triclosan: The antimicrobial agent emerging as a toxicant

Several scientific studies have suggested a link between increased exposure to pollutants and a rise in the number of neurodegenerative disorders of unknown origin. Notably, triclosan (an antimicrobial agent) is used in concentrations ranging from 0.3% to 1% in various consumer products. Recent studies have also highlighted triclosan as an emerging toxic pollutant due to its increasing global use. However, a definitive link is missing to associate the rising use of triclosan and the growing number of neurodegenerative disorders or neurotoxicity. In this article, we present systematic scientific evidence which are otherwise scattered to suggest that triclosan can indeed induce neurotoxic effects, especially in vertebrate organisms including humans. Mechanistically, triclosan affected important developmental and differentiation genes, structural genes, genes for signaling receptors and genes for neurotransmitter controlling enzymes. Triclosan-induced oxidative stress impacting cellular proteins and homeostasis which triggers apoptosis. Though the scientific evidence collated in this article unequivocally indicates that triclosan can cause neurotoxicity, further epidemiological studies may be needed to confirm the effects on humans.     

Leptocephalus eel larvae will feed in aquaria

Synopsis Premetamorphosing larvae of Muraenesox cinereus (Muraenesocidae) and Conger myriaster (Congridae), caught and kept alive in aquaria, repeatedly bit pieces out of a lump of squid paste. By coloring the paste with Brilliant Red, ingestion and defecation were clearly seen through the transparent gut. The paste is not their natural food, but nevertheless a possible food item for rearing eels from eggs; most previous efforts have failed inasmuch as the larvae have starved.     

Apios americana,a fly-pollinated papilionaceous flower?

In the flowers ofApios americana the vexillum remains ± in its bud position. In this way, a dark cavity is formed displaying a bright window at its base. Insect visitors are attracted to the hidden inflorescences by scent. In their attempt to reach the window they trigger an explosive release of stigma and pollen. Stigmatic fluid glues pollen to the visitor. All characters of the flower fit well into the myiophilous syndrome and thus flies are expected to be the proper pollinators.Apios americana seems to be the only myiophilous exception within the predominantly melittophilousFabaceae.     

Spatial components of foraging behavior in an African Ponerine ant,Paltothyreus tarsatus

Colonies of the African stink ant Paltothyreus tarsatuslocated in the forest have nests with shorter horizontal galleries and a smaller total foraging surface than colonies located in open areas. Each solitary worker specializes on the same central or peripheral hunting zone but she does not specialize on a particular sector during group-retrieving. The search for prey is characterized by a wandering walk with spatial parameters varying in two ways. Capture of a termite releases a path characterized by sinuosity and a decrease in speed of movement. In contrast, a failure in the course of an attempted capture releases an increase in both sinuosity and speed of movement corresponding to a socalled reserve behavior. Each worker shortens her retrieving trip in comparison with her search trip and the straightness of the homing paths depends on the size and shape of the prey. Our data show that behavioral flexibility at the individual level in P. tarsatusis important in determining spatial foraging strategy at the colony level.     

Cartesian representation of stimulus direction: Parallel processing by two sets of giant interneurons in the cockroach

The cockroachPeriplaneta americana responds to wind puffs by turning away, both on the ground and when flying. While on the ground, the ventral giant interneurons (ventrals) encode the wind direction and specify turn direction, whereas while flying the dorsal giant interneurons (dorsals) appear to do so. We report here on responses of these cells to controlled wind stimuli of different directions. Using improved methods of wind stimulation and of positioning the animal revealed important principles of organization not previously observed.All six cells of largest axonal diameter on each side respond preferentially to ipsilateral winds. One of these cells, previously thought to respond non-directionally (giant interneuron 2), was found to have a restricted directional response (Fig. 3). The organization of directional coding among the ventral giant interneurons is nearly identical to that among the dorsals (Fig. 2). Each group contains, on each side, one cell that responds primarily to wind from the ipsilateral front, another primarily in the ipsilateral rear, and a third responding more broadly to ipsilateral front and rear.These results are discussed in terms of the mechanisms of directional localization by the assembly of giant interneurons.Abbreviations GI giant interneuron - vGI ventral giant interneuron - dGI dorsal giant interneuron - CF 5-carboxyfluorescein - A6 6th abdominal ganglion - TI thoracic interneuron - BED best excitatory direction