The effect of aging and caloric restriction on mitochondrial protein density and oxygen consumption

It has been proposed that part of the anti-aging mechanism of caloric restriction (CR) involves changes in mitochondrial function. To investigate this hypothesis, mitochondria from various tissues of male Brown Norway rats (fully fed and CR) were isolated and respiration rates determined. In mitochondria from liver, heart, brain and kidney, there were no significant effects of CR on state 4 mitochondrial respiration rate. Further experiments using liver mitochondria under a variety of incubation conditions confirmed that CR does not alter mitochondrial respiration rate in this tissue. However, the respiration rate of mitochondria from brown adipose tissue (BAT) of CR animals was approximately three-fold higher compared to mitochondria from fully fed controls. Mitochondrial protein density was significantly higher in liver tissue of CR animals; it was significantly lower in heart and unchanged in BAT. It is concluded that whilst CR results in tissue-specific changes in mitochondrial respiration rate, these effects do not explain the CR-induced changes in free radical production reported previously for these organelles.

Effect of caloric restriction on mitochondrial reactive oxygen species production and bioenergetics: reversal by insulin

To gain insight into the antiaging mechanisms of caloric restriction (CR), mitochondria from liver tissue of male Brown Norway rats were used to study the effects of CR and insulin on mitochondrial reactive oxygen species production and bioenergetics. As assessed by hydrogen peroxide measurement, CR resulted in a decrease in the production rate of reactive oxygen species. This decrease was attributed to a decrease in protonmotive force in mitochondria from the CR animals. The decrease in protonmotive force resulted from an increase in proton leak activity and a concomitant decrease in substrate oxidation activity. Each of these effects of CR was reversed by subjecting CR animals to 2 wk of insulin treatment. To achieve continuous and stable insulin delivery, animals were placed under temporary halothane anesthesia and miniosmotic pumps were implanted subcutaneously. To gain further insight into how CR and insulin exerted its effects on mitochondrial bioenergetics, the effects of CR and insulin were quantified using modular metabolic control analysis. This analysis revealed that the effects of CR were transmitted through different reaction branches of the bioenergetic system, and insulin reversed the effects of CR by acting through the same branches. These results provide a plausible mechanism by which mitochondrial reactive oxygen species production is lowered by CR and a complete description of the effects of CR on mitochondrial bioenergetics. They also indicate that these changes may be due to lowered insulin concentrations and altered insulin signaling in the CR animal.

Developing a model based decision support tool for the identification of sustainable treatment options for domestic wastewater

To enable decision makers to select sustainable wastewater treatment systems, insight into the sustainability of a wide variety of systems should be provided in a transparent way leaving room for adaptation and interpretation according to the local situation. To provide this insight a structured methodology comparing wastewater treatment systems with respect to sustainability is defined. Similar to life cycle assessment (LCA) three phases can be distinguished: (1) goal and scope definition, (2) inventory analysis, and (3) optimisation and results. In the goal and scope definition we set the system boundaries to include most of the water cycle and part of the food cycle. Furthermore, we defined a multi-disciplinary set of sustainability indicators including technical, economic, environmental, and socio-cultural aspects. In the inventory analysis these sustainability indicators are quantified using simple static models of wastewater unit operations. Selection of unit operations results in a model of a complete wastewater treatment system. In the optimisation phase the decision maker can weigh the different sustainability indicators and select sustainable options through integer programming.

Use of primary cultures of rat hepatocytes for the study of ageing and caloric restriction

Primary cultures of hepatocytes are widely used to investigate liver function, but this technology has not been exploited fully in the study of ageing and caloric restriction (CR). Hepatocytes were isolated from adult and aged, fully fed, and calorie restricted male Sprague-Dawley rats and their viability and biochemical status assessed over 48h in primary culture. The in vivo differences in cellular protein and DNA content due to age and CR were maintained over the 48h experimental period. The results of this study confirm earlier reports that protein synthesis and degradation rates decline with age in liver tissue, and this decline is retarded by CR. Rates of protein synthesis and degradation in the first year of life were depressed in response to CR feeding and were only significantly higher than recorded for control animals during the second year of life. Cells from rats of both ages and diets maintained linear rates of extracellular protein synthesis, intracellular protein synthesis, protein degradation and albumin secretion between 24 and 48h in culture. These findings indicate that hepatocytes from CR rats did not respond adversely to the relatively rich culture medium and cells from CR animals did not immediately revert to the fully fed phenotype.

The balance model of dyslexia and remedial training: an evaluative study

The aim of this study was to test the validity of Bakker's (1983, 1990) theory and treatment paradigm of dyslexia. Twenty-one children (mean age = 9.9 years) categorized as P-type dyslexics (showing accurate but slow and fragmented reading) and 19 children (mean age = 9.7 years) categorized as L-type dyslexics (fast but inaccurate readers) were presented with hemisphere-specific stimulation (HSS) and hemisphere-alluding stimulation (HAS). HSS was produced by presenting words to either the left or the right visual half-field, or to the left or right hand of the participant. HAS training was achieved through the presentation of either semantically/phonetically demanding or perceptually demanding text. Participants were given either a treatment program that was specifically designed for their particular dyslexia subtype, or a program that had been deliberately chosen to be inconsistent with their subtype. Contrary to predictions, participants made gains on all of the reading measures, regardless of the type of treatment given. On the basis of these findings it is suggested that treatment gains made are due to nonspecific training effects and not to the specific nature of Bakker's remedial strategies.

Linear systems approach to simulation of optical diffraction

The diffractive processes within an optical system can be simulated by computer to compute the diffraction-altered electric-field distribution at the output of the system from the electric-field distribution at the input. In the paraxial approximation the system can be described by an ABCD ray matrix whose elements in turn can be used to simplify the computation such that only a single computational step is required. We describe two rearrangements of such computations that allow the simulation to be expressed in a linear systems formulation, in particular using the fast-Fourier-transform algorithm. We investigate the sampling requirements for the kernel-modifying function or chirp that arises. We also use the special properties of the chirp to determine the spreading imposed by the diffraction. This knowledge can be used to reduce the computation if only a limited region of either the input or the output is of interest.

Mood and the correction of positive versus negative stereotypes

The present research examined the effects of sadness on the correction of social stereotypes. Participants who either were not induced to feel sad were asked to form an impression of a single individual who belonged to a group that had either stereotypically positive or negative implications. Experiments 1 and 2 showed that sad people corrected for their negative, but not for their positive stereotypes. Experiment 3 demonstrated that this asymmetry was not due to stereotype valence per se but to whether the stereotype was perceived as an inappropriate basis for judgment. A model is presented that suggests that sad people do not simply ignore category-based information, but rather correct for their stereotypes only when they are perceived as inappropriate, which tends to be more often the case if the stereotype is negative than if it is positive. The implications of the present results for 4 extant models of mood and information processing are discussed.

Antisaccadic eye movements and attentional asymmetry in schizophrenia in three Pacific populations

Antisaccadic eye movements were examined in 50 patients with schizophrenia and in 77 controls in three Pacific populations, namely New Zealand, Palau and Papua New Guinea. Despite the great biocultural variation encompassed by these three populations, schizophrenic patients made significantly more antisaccadic-errors than controls (36% vs. 13%), as has been demonstrated previously in other populations. This neurocognitive deficit may be consistent with frontal lobe dysfunction in schizophrenia. In addition, patients with schizophrenia made significantly more errors than expected when the target was presented in the right visual field (RVF). This trend was observed in patients from all three study areas, and was not seen in any of the control populations. Antisaccadic test performance in schizophrenia may be influenced by lateralized (left hemisphere) neuroanatomical impairment.

Spatial orienting controlled without awareness: a semantically based implicit learning effect

Three experiments tested whether spatial attention can be influenced by a predictive relation between incidental information and the location of target events. Subjects performed a simple dot detection task; 600 msec prior to each target a word was presented briefly 5 degrees to the left or right of fixation. There was a predictive relationship between the semantic category (living or non-living) of the words and target location. However, subjects were instructed to ignore the words, and a post-experiment questionnaire confirmed that they remained unaware of the word-target relationship. In all three experiments, given some practice on the task, response times were faster when target appeared at likely ( p = 0.8 ), compared to unlikely ( p = 0.2 ) locations, in relation to lateral word category. Experiments 2 and 3 confirmed that this effect was driven by semantic encoding of the irrelevant words, and not by repetition of individual stimuli. Theoretical implications of this finding are discussed.

Person memory and judgment: pragmatic influences on impressions formed in a social context

Ss who receive information about a person's traits and behaviors in a social context are likely to focus their attention on the pragmatic implications of this information (i.e., why the information was conveyed). To examine this hypothesis, Ss listened to a taped conversation in which a male target (T) and another speaker (O) exchanged anecdotal accounts of T's behavior. Ss typically used O's trait description of T to form an evaluative concept of O rather than of T, whereas T's trait description of himself had no effect on evaluations of him. Ss had better recall of statements O made when they were unfavorable and, therefore, violated a conversational norm to be polite. However, behaviors that T himself mentioned were often recalled better when they were favorable, and therefore, in violation of a normative expectation to appear modest. The inconsistency of T's behaviors with initial trait descriptions of him had little effect on the recall of these behaviors.

Attentional interaction in the split-brain: evidence from negative priming

Negative priming refers to an inhibitory effect, in which responding is slower when an attended target is identical, or related to a previously ignored distractor. It has been suggested that the processes underlying this effect are important for maintaining attentional focus and orientation. A version of this paradigm, in which subjects attended to digits presented to the RVF, and ignored digits presented to the LVF was employed with two split-brain subjects and seven normal controls. The task was to categorize RVF digits as odd or even. Each of the split-brain patients showed significant amounts of negative priming from ignored LVF distractors, as did the normal control subjects. It is concluded that even in the split-brain there are rich attentional interactions with respect to complex attributes encoded within each hemisphere. It is suggested that these rely on interaction between cortical and subcortical processing, and may play an important role in relation to the unified and apparently well integrated behaviour of commissurotomy patients in everyday settings.

Spatial attention and expectancy for colour, category and location: further evidence against the spotlight model

A study of spatial attention is reported in which different colours and categories of object tended to appear at different locations. Subjects made speeded orientation judgements to alphanumeric characters that could appear either above or below the centre of a display. In the Colour Condition subjects were informed that red characters tended to appear at one location (p = 0.8), while green characters tended to appear at the other. In the Category Condition letters tended to appear at one location, and digits at the other. Before each trial subjects were cued to expect either a red or a green character (Colour Condition); or a letter or a digit (Category Condition). It was found that spatial selectivity varied according to the colour, or category of object presented. The latter finding replicated an earlier report (Lambert 1987). Spatial selectivity was appropriate for the character presented, even when it was in the uncued colour (or category). It is concluded that subjects are able to form and make use of complex attentional expectancies concerning combinations of colour with location, and category with location. Theoretical implications of these results are discussed.

The self and social judgment: effects of affective reaction and "own position" on judgments of unambiguous and ambiguous information about others

Ss who differed in the extremity of self-definition ("own position") with respect to a given trait (sociability, independence, or patience) made trait and evaluative judgments of behavioral stimuli that varied in their descriptive implications for that trait. Across 4 experiments, individual differences in trait ratings of unambiguous information were mediated largely by differences in Ss' affective reactions to these stimuli rather than by direct use of own position as a judgmental anchor. When the target information was ambiguous, however, own position influenced trait judgments independently of Ss' affective reactions to these stimuli. These latter effects were moderated by either encoding or informational mechanisms. A theoretical framework is presented that accounts for these results and predicts how effects of self-knowledge on judgments of others should vary across different trait dimensions.

The self and social judgment: Effects of affective reaction and "own position" on judgments of unambiguous and ambiguous information about others

Ss who differed in the extremity of self-definition ("own position") with respect to a given trait (sociability, independence, or patience) made trait and evaluative judgments of behavioral stimuli that varied in their descriptive implications for that trait. Across 4 experiments, individual differences in trait ratings of unambiguous information were mediated largely by differences in Ss' affective reactions to these stimuli rather than by direct use of own position as a judgmental anchor. When the target information was ambiguous, however, own position influenced trait judgments independently of Ss' affective reactions to these stimuli. These latter effects were moderated by either encoding or informational mechanisms. A theoretical framework is presented that accounts for these results and predicts how effects of self-knowledge on judgments of others should vary across different trait dimensions.

Interhemispheric interaction in the split-brain

An experiment is reported in which a split-brain patient (LB) was simultaneously presented with two words, one to the left and one to the right of fixation. He was instructed to categorize the right sided word (living vs non-living), and to ignore anything appearing to the left of fixation. LB's performance on this task closely resembled that of normal neurologically intact individuals. Manual response speed was slower when the unattended (left visual field) word belonged to the same category as the right visual field word. Implications of this finding for views of the split-brain syndrome are discussed.

Stereotypes and social judgment: the effects of typicality and group heterogeneity

Two experiments showed that when subjects believed a group to be heterogenous, they based their liking for a particular group member on their liking for the group as a whole, independently of and in addition to the target's behavior, and regardless of the target's typicality. When they believed the group to be homogenous, however, they treated the target's typicality as a favorable or unfavorable attribute, which affected their evaluation. The latter subjects used their group stereotype as a standard of comparison in judging the implications of the target's behavior for a trait to which it was relevant. All subjects' stereotypes had a positive influence on judgments of stereotyped-related traits for which the target's behavior was uninformative. A conceptualization is proposed to account for these findings.

Cognitive representation of conversations about persons

Ss listened to a man and woman discuss the behaviors of a third, target person. First, however, they received handwritten sets of trait adjectives that each speaker had ostensibly used to describe the target before engaging in the conversation. Ss with the objective of forming an impression of the target person had better recall of behaviors if they were evaluatively inconsistent with the female speaker's trait description of the target. However, the behaviors' consistency with the male speaker's description of the target had little influence. When Ss listened to the conversation with instructions to infer each speaker's impression of the target, they typically had better recall of behaviors that were inconsistent with trait descriptions provided by the particular speaker who mentioned them. When they were told to form impressions of the speakers themselves, however, Ss had generally better recall of the behaviors mentioned by a given speaker when they were inconsistent with the trait description provided by the other speaker. Existing models of person memory and judgment could not account a priori for either these results or for judgments of the target and speakers.

Cognitive representation of conversations about persons

Ss listened to a man and woman discuss the behaviors of a third, target person. First, however, they received handwritten sets of trait adjectives that each speaker had ostensibly used to describe the target before engaging in the conversation. Ss with the objective of forming an impression of the target person had better recall of behaviors if they were evaluatively inconsistent with the female speaker's trait description of the target. However, the behaviors' consistency with the male speaker's description of the target had little influence. When Ss listened to the conversation with instructions to infer each speaker's impression of the target, they typically had better recall of behaviors that were inconsistent with trait descriptions provided by the particular speaker who mentioned them. When they were told to form impressions of the speakers themselves, however, Ss had generally better recall of the behaviors mentioned by a given speaker when they were inconsistent with the trait description provided by the other speaker. Existing models of person memory and judgment could not account a priori for either these results or for judgments of the target and speakers.

Stereotypes and social judgment: The effects of typicality and group heterogeneity

Two experiments showed that when subjects believed a group to be heterogenous, they based their liking for a particular group member on their liking for the group as a whole, independently of and in addition to the target's behavior, and regardless of the target's typicality. When they believed the group to be homogenous, however, they treated the target's typicality as a favorable or unfavorable attribute, which affected their evaluation. The latter subjects used their group stereotype as a standard of comparison in judging the implications of the target's behavior for a trait to which it was relevant. All subjects' stereotypes had a positive influence on judgments of stereotyped-related traits for which the target's behavior was uninformative. A conceptualization is proposed to account for these findings.

Selective attention, visual laterality, awareness, and perceiving the meaning of parafoveally presented words

Four experiments are reported investigating the effect of selective attention on the semantic encoding of parafoveally presented words. In Experiments 1 and 2 a right visual field (RVF) performance bias was found when subjects attended to words that could appear either left or right of centre (attend-side condition). When subjects attended centrally and ignored lateral distractor words (attendcentre condition) there was an inhibitory effect of word meaning from left visual field (LVF) distractors. Both inhibitory and facilitatory effects of semantic category were observed from unattended words in Experiments 3 and 4. The pattern of effects depended upon the direction of spatial bias in an attend-side condition. Both kinds of effect occurred even for subjects who were unable to make consciously directed semantic category decisions to words at the same eccentricity (4°) and exposure time (15 msec) as ignored distractors in the attend-centre condition. Implications of these findings for theories of selective attention, for the issue of semantic encoding independent of conscious awareness, and for theories of the relationship between lateral performance biases and functional hemispheric asymmetry are discussed.

Imageability does not interact with visual field in lateral word recognition with oral report

Four lateral tachistoscopic experiments are reported which tested the hypothesis that the right hemisphere has a selective ability to process highly imageable words (the RH imageability hypothesis). The prediction that performance asymmetry would vary as a function of word imageability, in a lateral recognition task with oral report, was not fulfilled. Results suggested that several previously published studies which hitherto have been regarded as supporting the RH imageability hypothesis may be discounted on artifactual grounds. The implications of these findings for the overall status of the hypothesis were discussed.