Fear information and social phobic beliefs in children: a prospective paradigm and preliminary results.

This paper presents a first attempt to develop a prospective paradigm to test Rachman's (Behav. Res. Ther. 15 (1977) 375) theory of fear acquisition for social fears. Following the prospective paradigm for animal fears developed by Field et al. (Behav. Res. Ther. 39 (2001) 1259) an attempt is made to adapt this paradigm to look at the effect of fear information in the development of social fears. A large group of normal children (N=135) who were at an age (10-13 years) at which social concerns are most pertinent were tested using this paradigm. They were given positive, negative or neutral information about three social situations: public speaking, eating in public, and meeting a new group of children. Children's fear beliefs were measured before and after the information was given and the information was given by a teacher, a same age peer or no information was given (a control). The results indicate that although information can change social fear beliefs it is dependent upon the type of social activity and who provides the information. The implications of these initial results for our understanding of both the role of fear information in the development of social fear beliefs, and the limitations of this current paradigm are discussed.

Who's afraid of the big bad wolf: a prospective paradigm to test Rachman's indirect pathways in children.

Rachman's theory [The conditioning theory of fear insition: a critical examination. Behav. Res. Ther. 15 (1977) 375-387] of fear acquisition suggests that fears and phobias can be acquired through three pathways: direct conditioning, vicarious learning and information/instruction. Although retrospective studies have provided some evidence for these pathways in the development of phobias during childhood [see King, Gullone, & Ollendick, Etiology of childhood phobias: current status of Rachman's three pathway's theory. Behav. Res. Ther. 36 (1998) 297-309 for a review], these studies have relied on long-term past memories of adult phobics or their parents. The current study was aimed towards developing a paradigm in which the plausibility of Rachman's indirect pathways could be investigated prospectively. In Experiment 1, children aged between 7 and 9 were presented with two types of information about novel stimuli (two monsters): video information and verbal information in the form of a story. Fear-related beliefs about the monsters changed significantly as a result of verbal information but not video information. Having established an operational paradigm, Experiment 2 looked at whether the source of verbal information had an effect on changes in fear-beliefs. Using the same paradigm, information about the monsters was provided by either a teacher, an adult stranger or a peer, or no information was given. Again, verbal information significantly changed fear-beliefs, but only when the information came from an adult. The role of information in the acquisition of fear and maintenance of avoidant behaviour is discussed with reference to modern conditioning theories of fear acquisition.

Calcium-transport function of the chick embryonic chorioallantoic membrane. II. Functional involvement of calcium-binding protein, Ca2+-ATPase and carbonic anhydrase.

This study aimed to investigate the mechanism of active calcium transport in the chick embryonic chorioallantoic membrane (CAM) by assessing the functional involvement of three previously identified, putative components of the transport pathway. These components are a calcium-binding protein (CaBP), Ca2+-activated ATPase and carbonic anhydrase. Using specific reagents, including antibodies and enzyme inhibitors in vivo and in vitro in CAM calcium uptake assays, it was shown that these biochemically identified components were all functionally involved. The results of these studies also indicate that active calcium uptake by the CAM requires the presence of the CaBP on the cell surface in a laterally mobile manner, while carbonic anhydrase appeared to be a cytosolic component. We further analysed the subcellular location of the calcium-uptake activity by gel filtration and density-gradient fractionation of cell-free microsomes of the CAM and the results suggest that this activity is associated with the plasma membrane.

Calcium-transport function of the chick embryonic chorioallantoic membrane. I. In vivo and in vitro characterization.

During chick embryonic development, the chorioallantoic membrane (CAM) is responsible for the mobilization of shell calcium into the embryonic circulation. The calcium-transport function of the CAM was studied here by measuring CAM calcium uptake in vivo and in vitro. The in vivo technique involved the use of an uptake chamber constructed on top of the CAM in situ. The in vitro methods included two systems: CAM tissue disks and cell-free microsomal membranes isolated from the CAM. Analyses using these three assays show that calcium uptake by the CAM exhibited characteristics indicative of active transport, such as temperature dependence, saturability, energetic requirement and ion specificity. The data also show that calcium-uptake activities of the CAM increase as a function of embryonic age in a manner coincident with the increased accumulation of calcium by the developing embryo in ovo.

Calcium-activated ATPase of the chick embryonic chorioallantoic membrane. Identification, developmental expression, and topographic relationship with calcium-binding protein.

A Ca2+-activated ATPase activity is present in the chick embryonic chorioallantoic membrane (CAM), the placenta-like tissue which translocates eggshell calcium into the embryonic circulation. The enzyme is membrane-bound, ATP-specific, Mg2+-dependent, exhibits dual Km values of 30 microM and 0.3 mM Ca2+, and has a Mr of 170,000. Throughout embryonic development, a single electrophoretic form of the Ca2+-ATPase is found and, furthermore, its specific activity as a function of age follows a bimodal pattern. In particular, from incubation days 14-15 to the end of gestation, a period representing rapid embryonic calcium accumulation, Ca2+-ATPase specific activity increases 6-fold. Cytohistochemistry localized the Ca2+-ATPase exclusively within the CAM ectoderm which lies adjacent to the calcium-rich shell membrane/eggshell. In a parallel study, cleavable bifunctional cross-linking agents were used to characterize the in situ protein topography of the CAM ectodermal surface adjacent to the calcium-binding protein (CaBP), a CAM cell-surface protein associated with calcium transport. We found that the immediate near neighbor of the CaBP is a 170,000 Mr, membrane-bound protein. The 170,000 protein was co-isolated with the CaBP after cross-linkage in situ and subsequent immunoprecipitation with anti-CaBP antibodies. Reductive cleavage of the immune complex released detectable Ca2+-ATPase activity, suggesting that the 170,000 protein is the Ca2+-ATPase of the CAM.