TGF-beta: a balancing act

Regulation of developmental processes as well as host defense and repair mechanisms requires the maintenance of a delicate balance of positive and negative regulatory signals. TGF-beta, a molecule known for its many diverse activities, can promote or inhibit cell growth and function. Disruption of the balance between these opposing activities can contribute to aberrant development, malignancy, or pathogenic immune and inflammatory responses. TGF-beta transgenic mouse studies highlight the essential function(s) of TGF-beta and its receptors and provide insight to potential therapeutic approaches to manipulate TGF-beta expression.     

Developmental signalling: a careful balancing act

Embryos of arthropods and chordates are patterned along the dorso-ventral axis by a gradient of secreted morphogens of the Bmp4/Dpp family. This gradient now appears to be shaped by the opposing activities of Bmp-sequestering proteins, on the one hand, and Bmp-releasing metalloproteases, on the other.     

The preterm labor experience: a balancing act

The purpose of the study was to identify how women described, interpreted, and managed their preterm labor experience. Ten married, middle-class women participated in an in-depth, tape-recorded interview in the hospital after preterm labor was stabilized; periodically over the telephone after discharge from the hospital; and in the hospital, home, or via telephone after birth, for a total of 31 interviews. Using qualitative data analysis techniques, the findings were conceptualized as five recursive stages: becoming aware that something was wrong and feeling unbalanced, making sense of the experience as they sought to understand why preterm labor occurred, trying different strategies to re-create a balance in their lives, addressing other life stressors that threatened restoring balance, and emerging from the preterm labor experience with added growth. An increased understanding of the preterm labor experience from the women's perspective can be helpful to health care professionals and others who support women during pregnancy.     

The role of cytokines in bacterial pneumonia: an inflammatory balancing act

The effect of 2 mM ethanol, a concentration indicative of daily alcohol consumption, was investigated on trichloroethylene (TRI) metabolism in perfused Wistar rat liver. The study consisted of two parts: The first part studied TRI administration with or without ethanol. In the second study chloral hydrate (CH), an intermediate in TRI metabolism, was administered in the absence or presence of ethanol to phenobarbital (PB) treated or non-PB-treated rats. The concentrations of the metabolites, total trichloroethanol (TCE), and trichloroacetic acid (TCA) were measured by gas chromatography and intracellular reduced pyridine nucleotides by surface fluorometry. In the first study, ethanol infusion significantly increased the TCE/TCA ratio, TCE production rate, and percentage of reduced pyridine nucleotides, and decreased TCA production rate without an associated change in the sum of TCE and TCA formation rates. In the second study, ethanol infusion in the absence or presence of PB produced similar significant increases in the TCE/TCA ratio, TCE production rate, and percentage of reduced pyridine nucleotides, accompanied by a decrease in TCA formation. The observed shift in TRI metabolism in the presence of ethanol, from oxidation to TCA to reduction to TCE, suggests that alcohol exerts alterations in hepatic intracellular oxidation-reduction (redox) states.     

Analysis of an instrumental motor act

Different instrumental conditioned reactions were elaborated in dogs which suffered simultaneously from thirst and hunger. During the elaboration, not only external agents and the animal's own movements become conditioned stimuli but also any objects linked to these movements whose positive signal meaning is compared in the course of reinforcement with negative signal meaning of other objects and becomes differentiated. To achieve one and the same aim, different instrumental habits may be used, while the same habit may be used for achieving different aims. During instrumental conditioning any habit may acquire a generalized positive biological significance as a means of procuring.     

The act frequency approach to personality.

Personality dispositions are viewed as summaries of act frequencies that, in themselves, possess no explanatory status. As sociocultural emergents, dispositions function as natural cognitive categories with acts as members. Category boundaries are fuzzy, and acts within each category differ in their prototypicality of membership. This formulation is illustrated by a series of studies involving undergraduate raters, which focused on indices of act trends and on a comparative analysis of the internal structure of dispositions. The act frequency approach is placed within a taxonomic framework of the relations among act categories and hierarchic classification. Theoretical implications of the act frequency approach are examined. Dispositional consistency is distinguished from behavioral consistency, and several act frequency indices (e.g., dispositional versatility and situational scope) are defined. Situational analysis and personality coherence are viewed from the act frequency perspective. Discussion focuses on the possible origins and development of dispositional categories and implications of alternative middle-level constructs for act categorization and personality theory. (102 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)