Evidence that the modulation of membrane-associated protein kinase C activity by an endogenous inhibitor plays a role in N1E-115 murine neuroblastoma cell differentiation

Murine neuroblastoma cells, N1E-115, were induced to differentiate into neuron-like cells by serum deprivation for 18 h. As previous studies have shown that the suppression of protein kinase C (PKC) activity by selective inhibitors or neutralizing antibodies induces neuroblastoma cells to differentiate, we tested the hypothesis that serum deprivation may cause a rapid loss in membrane PKC activity that occurs well before the morphological changes that are characteristic of cell differentiation. A significant reduction in particulate (membrane) PKC activity was indeed observed within 3 h of serum withdrawal when enzyme activity was measured in intact native membranes by the recently described in vitro "direct" assay. This rapid reduction in enzyme activity was confirmed by the decreased phosphorylation of the MARCKS protein, an endogenous PKC-selective substrate, in intact cells. The decrease in membrane PKC activity occurred without any loss in the amount of membrane-associated enzyme, suggesting that some factor(s) resident in neuroblastoma membranes was suppressing PKC activity. Indeed, results indicate the presence of an endogenous inhibitor of PKC tightly associated with neuroblastoma membranes. This inhibitory activity increased in the membranes of cells subjected to serum deprivation, raising the possibility that it was likely responsible for the decline in membrane PKC activity in differentiating N1E-115 cells. Preliminary characterization indicated that the inhibitory activity is a protein and is localized mainly in the membrane fraction. Thus, these results demonstrate directly that endogenous inhibitor can regulate membrane-associated PKC activity in cells and thereby modulate PKC-related neuronal functions.     

The effects of lumbar massage on muscle fatigue, muscle oxygenation, low back discomfort, and driver performance during prolonged driving

An increasing dependence of society on automobiles for both work and leisure and the corresponding increase in time spent seated in the car has been correlated with a greater risk of low back pain and absence from work (Porter and Gyi 2002). This study examined the effects of three types of lumbar massage units on seating comfort, muscle fatigue, muscle oxygenation, muscle blood flow and driving performance during a 1 h simulated driving task. Electromyographic (EMG) signals were recorded from the right and left thoracic and lumbar erector spinae musculature. Average EMG (AEMG), mean power frequency (MPF), gaps and amplitude probability distribution function (APDF) parameters were analysed from the three massage seats and compared to a control seat. Near infrared spectroscopy (NIRS) and skin temperature from the right thoracic and lumbar erector spinae were used as an indication of muscle oxygenation and blood flow throughout the driving task. Ratings of perceived discomfort were used to assess driver discomfort, and driving performance was assessed by calculating mean lap times for the duration of each driving trial. The results showed statistically significant increases in skin temperature compared with the control seat after 60 min of driving. The NIRS results reflected these trends although the results were not statistically significant. AEMG and MPF measures showed no significant differences between the seats. MPF measures were found to increase over time, effects attributed to increases in muscle temperature. Gaps and APDF analyses revealed greater rest times and lower activation levels, respectively, with the control seat, which could result in increased loading of passive structures. This study demonstrated the beneficial effects of lumbar massage systems in increasing muscle blood flow and oxygenation. Although EMG parameters were not significantly different, the trends support the significant blood flow results. Future research should include longer driving times and adjustments in EMG measures to account for the effects of increasing muscle temperature on AEMG and MPF measures.     

Earth conductivity estimates from through-the-Earth electromagnetictransmission tests

Electromagnetic narrowband signals were transmitted through the Earth at 27 coal mines located throughout the United States. From these tests, apparent Earth conductivity values were derived based upon a homogeneous half-space model of the Earth. The derived conductivity values were found to be inversely proportional to the transmitted frequency and mine depth. This result is not consistent with the assumption of a homogeneous half-space Earth. A linear regression model relating the logarithm of the conductivity to the mine depth was formulated. The author found that the apparent Earth conductivity could be estimated from a linear combination of the transmitted frequency and mine depth     

Man & machine: I wonder if we can coexist

We have always had some fear of our machines. During the Industrial Revolution, for instance, we developed machines fueled by steam and oil to assist us in our labour-intensive tasks, and saw dramatic increases in our productivity. But we worried, maybe rightfully so, because we saw machines that outpaced us physically and we knew that we could not compete. After a while, we learned to accept them. It has been our nature to accept new technologies after we have seen how they can improve our way of life—at least up to now. Today we have a new type of machine to worry about. This one is powered not by steam but by knowledge, and is designed to aid us in our mental tasks. It is this design goal that troubles us the most. Perhaps it stems from the notion that although we can now accept being surpassed by machines in mechanical tasks, we consider mental creativity to be the province of humanity. The development of an intelligent machine, therefore, stirs our emotions. This paper looks at our emotional relationship with intelligent machines. It considers questions, both old and new, that may have concerned us about our machines and ourselves. To focus the discussion on this introspection, the paper takes a close look at the films "2001: A Space Odyssey" and "Artificial Intelligence: A.I." By no means does this paper answer the questions that we have lived with when building intelligent machines. It simply casts the questions in a light that we should consider.     

Introducing students to expert systems

Abstract: The emerging field of expert systems requires universities to address the educational requirements necessary to prepare students to enter and contribute to this field. This paper provides a guideline to educators on how to effectively introduce students to expert systems. This guideline describes the major objectives of an introductory course on expert systems, course topics, course material, and insight into how to effectively present the course. The recommendations made in this paper are a product of the experiences of the author gained over years of presenting such a course.     

Computer-mediated communication in adolescents with and without a history of specific language impairment (SLI)

The various uses of computer-mediated communication (CMC) are transforming the nature of social interactions and human relations among adolescents. Little is known about engagement of exceptional youth with this technology. The present study investigated the implications of language and social factors for frequency of CMC use and its relationship to adolescent well-being in young people with and without a history of specific language impairment (SLI). Eighty six adolescents with a history of SLI and 90 typically developing 17 year olds participated. Participants completed standardized assessments of psycholinguistic abilities and self-report measures of language motivations and social motivations for CMC use, as well as anxiety and depression. Results indicate that language abilities have a complex relationship with frequency of CMC use; social abilities have a more direct association and are predictive of frequency of CMC use. Both adolescents with SLI and typically developing adolescents were less shy online. No association was obtained between frequency of CMC use and reported emotional symptoms of anxiety and/or depression. It is argued that the characteristics of CMC, in terms of its less stringent language demands and its reduced-cues environment, can provide a medium for positive adaptation of adolescents with communication challenges.     

Wundt's American doctoral students.

Using the student records in the archives at Karl Marx University in Leipzig, Germany, 33 American students have been identified who took their doctoral degrees with Wilhelm Wundt. Wundt served as major reader (Erstgutachter) for 16 students and as secondary reader (Zweitgutachter) for another 17. Many of these students are unknown to psychologists, even among historians of psychology. This article provides the 1st comprehensive catalog of these students and includes information on their dissertation work and subsequent careers. Wundt's effect on his American students is also discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)