Biomedical subjects
Publications and source records attributed to J L Hicks.
Hard-tissue and soft-tissue landmarks of the face and oral cavity are introduced. Definitions for anatomic structures are listed, and figures to aid clinical examination are provided. Relevance of these landmarks to examination, diagnosis, and function is made.
Five experiments were conducted to explore how the character of the retention interval affected event-based prospective memory. According to the canons of retrospective memory, prospective performance should have been worse with increasing delays between intention formation and the time it was appropriate to complete an action. That result did not occur. Rather, prospective memory was better with increasing retention intervals in Experiments 1A, 1B, and 3. In manipulating the nature of the retention interval, the authors found that there were independent contributions of retention interval length and the number of intervening activities, with more activities leading to better prospective memory (Experiments 2 and 3). The identical retention intervals did not improve retrospective memory in Experiment 4. Theoretical explanations for these dissociations between prospective and retrospective memory are considered.
Three experiments were conducted to investigate the relationship between the credibility of information and later unconscious plagiarism of that information. In each experiment, ideas concerning ways to reduce traffic accidents were presented from a more credible source (traffic planners) and a less credible source (college freshmen). After a distractor task, participants were asked to generate novel ways to reduce traffic accidents. In Experiments 1 and 2, unconscious plagiarism of ideas presented from the more credible source was greater than from the less credible source. In neither experiment was explicit memory for ideas from each source different in tests of source monitoring or free recall. However, the difference in unconscious plagiarism was eliminated in Experiment 3 by having participants generate the implications of ideas at study. The results are discussed in terms of the explicit factors that affect the incidence of unconscious plagiarism.
We have identified partial loss of function mutations in class VI unconventional myosin, 95F myosin, which results in male sterility. During spermatogenesis the germ line precursor cells undergo mitosis and meiosis to form a bundle of 64 spermatids. The spermatids remain interconnected by cytoplasmic bridges until individualization. The process of individualization involves the formation of a complex of cytoskeletal proteins and membrane, the individualization complex (IC), around the spermatid nuclei. This complex traverses the length of each spermatid resolving the shared membrane into a single membrane enclosing each spermatid. We have determined that 95F myosin is a component of the IC whose function is essential for individualization. In wild-type testes, 95F myosin localizes to the leading edge of the IC. Two independent mutations in 95F myosin reduce the amount of 95F myosin in only a subset of tissues, including the testes. This reduction of 95F myosin causes male sterility as a result of defects in spermatid individualization. Germ line transformation with the 95F myosin heavy chain cDNA rescues the male sterility phenotype. IC movement is aberrant in these 95F myosin mutants, indicating a critical role for 95F myosin in IC movement. This report is the first identification of a component of the IC other than actin. We propose that 95F myosin is a motor that participates in membrane reorganization during individualization.
The intention superiority effect is the finding that intentions to perform an activity are stored in a heightened state of activation. The effect has also been generalized to the finding that once an intention is fulfilled, it is inhibited relative to more neutral material about which no intentionality has been formed. In two experiments, we tested some ecological and naturally occurring situations taken from the literature on prospective memory and demonstrated that they have consistent consequences for the activation level of an intention. In Experiment 1, a constellation of unrelated activities displayed heightened activation prior to completion and displayed inhibition after completion. In Experiment 2, canceling the intention resulted in inhibition just as completing the intention does in this paradigm. The results are discussed in terms of their practical and theoretical importance to theories of prospective memory.
Three experiments explored how participants solved a very open-ended generative problem-solving task. Previous research has shown that when participants are shown examples, novel creations will tend to conform to features shared across those examples (Smith, Ward, & Schumacher, 1993). We made the shared features of the examples conceptually related to one another. We found that when the features were related to the concept of hostility, participants' creations contained hostile features that were not part of any of the examples. These results suggest that participants will design novel entities to be consistent with emergent properties of examples shown to them. We also found that a mild hostility prime from unscrambling sentences had a similar conceptual effect. Together, the two effects suggest that conceptual priming of generative cognitive tasks will influence the cognitive aspects of the creative process.
A class of high-affinity inhibitors is disclosed that selectively target and irreversibly inactivate the epidermal growth factor receptor tyrosine kinase through specific, covalent modification of a cysteine residue present in the ATP binding pocket. A series of experiments employing MS, molecular modeling, site-directed mutagenesis, and 14C-labeling studies in viable cells unequivocally demonstrate that these compounds selectively bind to the catalytic domain of the epidermal growth factor receptor with a 1:1 stoichiometry and alkylate Cys-773. While the compounds are essentially nonreactive in solution, they are subject to rapid nucleophilic attack by this particular amino acid when bound in the ATP pocket. The molecular orientation and positioning of the acrylamide group in these inhibitors in relation to Cys-773 entirely support these results as determined from docking experiments in a homology-built molecular model of the ATP site. Evidence is also presented to indicate that the compounds interact in an analogous fashion with erbB2 but have no activity against the other receptor tyrosine kinases or intracellular tyrosine kinases that were tested in this study. Finally, a direct comparison between 6-acrylamido-4-anilinoquinazoline and an equally potent but reversible analog shows that the irreversible inhibitor has far superior in vivo antitumor activity in a human epidermoid carcinoma xenograft model with no overt toxicity at therapeutically active doses. The activity profile for this compound is prototypical of a generation of tyrosine kinase inhibitors with great promise for therapeutic significance in the treatment of proliferative disease.
In 5 experiments, the character of concurrent cognitive processing was manipulated during an event-based prospective memory task. High- and low-load conditions that differed only in the difficulty of the concurrent task were tested in each experiment. In Experiments 1 and 2, attention-demanding tasks from the literature on executive control produced decrements in prospective memory. In Experiment 3, attention was divided by different loads of articulatory suppression that did not ultimately lead to decrements in prospective memory. A high-load manipulation of a visuospatial task requiring performance monitoring resulted in worse prospective memory in Experiment 4, whereas in Experiment 5 a visuospatial task with little monitoring did not. Results are discussed in terms of executive functions, such as planning and monitoring, that appear to be critical to successful event-based prospective memory.
Prospective memory, remembering to carry out one's planned activities, was investigated using a naturalistic paradigm. Three experiments, with a total of 405 participants, were conducted. The goal was to demonstrate that the cognitive processing underlying successful everyday prospective remembering involves components other than mere "memory." Those components are probably best represented as individual differences in various cognitive capacities. More specifically, metamemory, attentional capacities, and planning processes that reprioritize intentions according to the demands of everyday life may determine how people actually accomplish the plans they establish for themselves. The results of these experiments suggest that researchers interested in the topic will have to contend with a multidimensional set of factors before any comprehensive understanding of prospective remembering can be realized.
In the revelation effect, the probability of labeling a target or a lure as "old" on item recognition tests increases if just prior to their recognition judgment, participants first identify a disguised version of the test item. The same occurs with interpolated tasks that occur just prior to a recognition judgment if the task shares constituents with the test items. One explanation of this test bias is an increased feeling of familiarity that comes from the identification stage preceding the recognition judgment (e.g., D. C. LeCompte, 1995; C. R. Lou, 1993). This study's finding in 4 experiments that 2-alternative forced-choice recognition either yields no effects of revelation or an "antirevelation" effect, even when both items were studied or nonstudied, is incongruent with this explanation. The authors argue that revelation decrements familiarity, and this results in a more liberal criterion shift. They also argue that their theory is more consistent with previous empirical data.
When a memory test is unexpected, recall performance is quite poor at retention intervals as short as 2-4 seconds. Orienting tasks that change encoding conditions are known to affect forgetting in such "very rapid forgetting" paradigms where people are misled to believe that recall will not be required. We evaluated the hypothesis that differences in forgetting among orienting tasks are attributable to contributions of secondary memory during encoding in two experiments. In Experiment 1, short-term recall performance was inversely related to task demands during encoding, although long-term memory performance was not. Task demands were assessed by making the duration of stimulus presentation dependent on the time required to perform three different orienting tasks. In Experiment 2, we compared performance of that variable-length stimulus presentation to the fixed-length presentation used in most prior research. The results suggested that additional encoding or rehearsal time does not have an appreciable impact on short-term performance. Thus, differences in forgetting appeared to be a function of the contribution of secondary memory rather than a function of the time available to engage in primary memory rehearsal strategies.
This article presents the results of a small workgroup convened by the American Association of Dental Schools to examine experiences related to establishing and conducting dental education programs that have significant affiliations with community-based clinical care settings. The workgroup meeting is a component of the association's effort to identify and promote innovative and non-traditional methods by which the number of postdoctoral general dentistry (PGD) positions can be increased to meet current demand for PGD education. The participants identified factors and conditions believed to be critical to successful program linkages. The information should be helpful to others as they consider opportunities to establish PGD programs or increase their number of PGD training positions.
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The ninaC proteins are found in Drosophila photoreceptor cells. Their primary sequences suggest they are kinase/myosin chimeras, but their myosin head-like domain is the most divergent amongst all the myosin-like proteins described to date. To investigate possible roles of the ninaC proteins in cell structure, we examined the ultrastructure of the photoreceptor cells in various ninaC mutants, and tested the ability of the proteins to interact with actin filaments in a myosin-like manner. In flies lacking the larger ninaC protein, p174, an ultrastructural phenotype was evident before eclosion. The axial actin cytoskeleton of the rhabdomeral microvilli appeared either fragmented or as an isolated structure, without linkage to the microvillar membrane. Deletion of the myosin head-like domain or the calmodulin-binding domain of p174 resulted in a similar abnormal cytoskeleton. Breakdown of the rhabdomeres followed, although at different rates depending on the deletion. Lack of the smaller protein, p132, per se did not result in photoreceptor degeneration, but in older flies there was an abnormal accumulation of multivesicular bodies. Moreover, the presence of p132 retarded the degeneration that occurs in the absence of p174, even though the p132 remained outside the rhabdomere. Biochemical studies showed that both ninaC proteins bind actin filaments and cosediment with actin filaments in an ATP-sensitive manner. These results outline structural roles for the ninaC proteins, and are consistent with the notion, suggested by their amino acid sequences, that the proteins are actin-based mechanoenzymes.
Three experiments were performed to test Smith, Ward, and Schumacher's (1993) conformity hypothesis-that people's ideas will conform to examples they are shown in a creative generation task. Conformity was observed in all three experiments; participants tended to incorporate critical features of experimenter-provided examples. However, examination of total output, elaborateness of design, and the noncritical features did not confirm that the conformity effect constrained creative output in any of the three experiments. Increasing the number of examples increased the conformity effect (Experiment 1). Examples that covaried features that are naturally uncorrelated in the real world led to a greater subjective rating of creativity (Experiment 2). A delay between presentation and test increased conformity (Experiment 3), just as models of inadvertent plagiarism would predict. The explanatory power of theoretical accounts such as activation, retrieval blocking, structured imagination, and category abstraction are evaluated.
Calcium signaling within astrocytes in the CNS may play a role comparable to that of electrical signaling within neurons. ATP is a molecule known to produce Ca2+ responses in astrocytes, and has been implicated as a mediator of intercellular Ca2+ signaling in other types of nonexcitable cells. We characterized the signal transduction pathway for ATP-evoked Ca2+ responses in cultured astrocytes from the dorsal spinal cord. Nearly 100% of these astrocytes respond to extracellularly applied ATP, which causes release of Ca2+ from an intracellular pool that is sensitive to thapsigargin and insensitive to caffeine. We found that intracellular administration of IP3 also caused release of Ca2+ from a thapsigargin-sensitive intracellular pool, and that IP3 abolished the response to ATP. The ATP-evoked Ca2+ response was blocked by the IP3 receptor antagonist heparin, applied intracellularly, but not by N-desulfated heparin, which is not an antagonist at these receptors. The Ca2+ response caused by ATP was also blocked by a phospholipase C inhibitor, U-73122, but not by its inactive analog, U-73343. Increases in [Ca2+]i were elicited by intracellular application of activators of heterotrimeric G-proteins, GTP gamma S and AIF4-. On the other hand, [Ca2+], was unaffected by a G-protein inhibitor, GDP beta S, but it did abolish the Ca2+ response to ATP. Pretreating the cultures with pertussis toxin did not affect responses to ATP. Our results indicate that in astrocytes ATP-evoked release of intracellular Ca2+ is mediated by IP3 produced as a result of activating phospholipase C coupled to ATP receptors via a G-protein that is insensitive to pertussis toxin. ATP is known to be released under physiological and pathological circumstances, and therefore signaling via the PLC-IP3 pathway in astrocytes is a potentially important mechanism by which ATP may play a role in CNS function.
ATP has been proposed as a possible chemical mediator of synaptic transmission in the spinal dorsal horn on the basis that it is released in dorsal horn synaptosomes in a Ca(2+)-dependent manner and that its effects mimic those of synaptic inputs to dorsal horn neurons. In the present study we examined the actions of ATP on neurons and glia in cell culture using optical and electrophysiological recording techniques. We found that ATP increased intracellular Ca2+ concentration ([Ca2+]i) in > 99% of astrocytes. In contrast, only 35% of neurons and 20% of oligodendrocytes responded to ATP. The prevalence of the ATP-evoked response in astrocytes led us to characterize the type of receptor mediating the response, the source of Ca2+, and the membrane currents activated by ATP. We found that ADP was approximately equipotent with ATP in increasing [Ca2+]i whereas AMP and adenosine had no effect. In addition, responses to ATP were blocked in a concentration-dependent manner by the P2 purinergic receptor antagonist suramin. Furthermore, as it was found that 2-methylthio-ATP was more potent than ATP and that beta, gamma-methylene-ATP was ineffective, the responses were mediated via the P2 gamma subtype of purinergic receptor. The increase in [Ca2+]i evoked by ATP persisted in extracellular medium with no added Ca2+ and containing EGTA, indicating that this increase was due to release of Ca2+ from intracellular stores. Release of Ca2+ by ATP was blocked by thapsigargin but was unaffected by caffeine. ATP had several effects on membrane current activating inward, outward, and mixed currents despite uniformly causing increases in [Ca2+]i. These observations indicate that ATP has diverse electrophysiological effects on astrocytes as well as increasing [Ca2+]i in these cells. We speculate that ATP released from synaptic terminals in the dorsal horn might act not only on postsynaptic neurons but also on perisynaptic astrocytes. Thus, a physiological role for ATP may be as a neuronal-glial signaling molecule within the spinal dorsal horn.
In September of 1991, all postgraduate general dentistry (PGD) program directors (Advanced Education in General Dentistry [AEGD] and General Practice Residency [GPR] directors [n = 325]) were surveyed to ascertain their opinions of the ideal goals and objectives of PGD programs. The response rate was 81.5 percent (n = 265). The directors rated the relative importance of various PGD program goals and objectives. The average of all the items rated was 3.4 on a scale ranging from 1 = unimportant to 4 = very important. The respondents identified several clinical and didactic subject areas that they considered very important including; infection control, CPR, dental and medical emergencies, diagnosing dentoalveolar trauma, diagnosing oral pathology, and assessment and treatment of patients with medical conditions. They also identified several training areas which were beyond the scope of a PGD program, e.g., research techniques, pediatric sedation, and selected advanced clinical procedures in dentistry (implantology and orthodontics) which require a long time to complete. In general, there was substantial agreement among the directors of different program types and sites as to the relative importance of various program goals. The largest differences were found among directors of programs from different sites, e.g., hospitals versus dental schools as opposed to directors from different program types, e.g., GPR versus AEGD. There is now a need to determine the relationship of these identified idealized goals and differences to program outcomes for the graduates of PGDs.