Nucleus-specific effects of meal duration on daily profiles of Period1 and Period2 protein expression in rats housed under restricted feeding.

Restricted feeding (RF) schedules provide a cycle of fasting and feeding each day and induce circadian rhythms in food-anticipatory activity. In addition, daily rhythms in the expression of circadian clock genes, such as rhythms in Period1 (PER1) or Period2 (PER2), are also shifted in many brain areas that are important for the regulation of motivation and emotion. In order to differentiate brain areas that respond to the time of food presentation from areas that are sensitive to the degree of restriction, the present study compared RF schedules that provided rats with either a 2 h-meal (2hRF) or a 6 h-meal (6hRF) each day. As expected, 2hRF was associated with less food-consumption, more weight-loss, and more food-anticipatory running-wheel activity than 6hRF. In association with these metabolic and behavioral differences, the daily pattern of PER1 and PER2 expression in the dorsomedial hypothalamic nucleus (DMH), which has been proposed to be integral to the generation and/or maintenance of food-anticipatory activities, peaked earlier in the 2hRF group and later in the 6hRF group. Because both RF groups exhibited approximately synchronous food-anticipatory activity, but phase shifted rhythms of PER1 and PER2 expression in the DMH, it suggests that the phase of food-anticipatory activity is not directly regulated by this brain area. Next, daily rhythms of PER2 expression in the limbic forebrain responded to each RF schedule in a nucleus-specific manner. In some brain areas, the amplitude of the PER2 rhythm was differentially adjusted in response to 2hRF and 6hRF, while other areas, responded similarly to both RF schedules. These findings demonstrate that daily rhythms of clock gene expression can be modulated by the motivational state of the animal, as influenced by meal duration, weight loss and food-consumption.

Food-entrainable circadian oscillators in the brain.

Circadian rhythms in mammalian behaviour and physiology rely on daily oscillations in the expression of canonical clock genes. Circadian rhythms in clock gene expression are observed in the master circadian clock, the suprachiasmatic nucleus but are also observed in many other brain regions that have diverse roles, including influences on motivational and emotional state, learning, hormone release and feeding. Increasingly, important links between circadian rhythms and metabolism are being uncovered. In particular, restricted feeding (RF) schedules which limit food availability to a single meal each day lead to the induction and entrainment of circadian rhythms in food-anticipatory activities in rodents. Food-anticipatory activities include increases in core body temperature, activity and hormone release in the hours leading up to the predictable mealtime. Crucially, RF schedules and the accompanying food-anticipatory activities are also associated with shifts in the daily oscillation of clock gene expression in diverse brain areas involved in feeding, energy balance, learning and memory, and motivation. Moreover, lesions of specific brain nuclei can affect the way rats will respond to RF, but have generally failed to eliminate all food-anticipatory activities. As a consequence, it is likely that a distributed neural system underlies the generation and regulation of food-anticipatory activities under RF. Thus, in the future, we would suggest that a more comprehensive approach should be taken, one that investigates the interactions between multiple circadian oscillators in the brain and body, and starts to report on potential neural systems rather than individual and discrete brain areas.

Managerial guidelines to support parents during the hospitalisation of their children in a private paediatric unit.

The purpose of this article is to describe managerial guidelines to support parents with the hospitalisation of their child in a private paediatric unit. The hospitalisation of a child is regarded as a major stressor for both parents and child. The role of the family in participating in a child's illness is slowly being recognised (Kibel & Wagstaff 2001:544), but the South African government per se has not yet issued any formal reports on parental participation in the hospitalisation process. The study explored and described the nursing care experiences of parents regarding the hospitalisation of their child in a paediatric unit; managerial guidelines to support parents with their lived experiences of their child's hospitalisation in a paediatric unit. To achieve the purpose and the objectives of the research, an interpretive-phenomenological qualitative approach was used in the research design and methods. Research was conducted through unstructured individual interviews, narrative diaries and field notes and data were analysed through open-coding (Tesch, 1990). Parents were asked to respond to the question "How did you experience your child's hospitalisation in the paediatric ward", followed by probing when the responses of the parents were ambiguous. Purposive sampling was used to achieve saturation of data and seven parents were interviewed and fifteen parents completed narrative diaries. The model of Lincoln and Guba (1985) was used to ensure trustworthiness. Ethical considerations were maintained throughout the study and consent was obtained from the respondents. The recommendations of the research were that attention should be given to 1) empowering parents to participate in their child's care; 2) guiding nursing personnel to plan the discharge process; 3) including parents in the unit routine; 4) fostering a trusting relationship with parents; 5) promoting the communication of information; and 6) creating a therapeutic environment for parents.

Experiences of parents during the hospitalisation of their child in a private paediatric unit.

A change in the health of a child is regarded as a major stressor for parents which further increases when the child is admitted to a hospital (Kaplan & Sadock, 1998:799). The role of the family in a child's illness is slowly being recognised (Kibel & Wagstaff, 2001:544), but the South African government per se has not yet issued any formal reports on parental participation in the hospitalisation process. The purpose of the study was to describe recommendations to support parents with the hospitalisation of their child in a private paediatric unit. An interpretive-phenomenological qualitative approach was followed through unstructured individual interviews, narrative diaries and field notes. Purposive sampling was used to achieve saturation of data. Seven parents were interviewed and 15 parents completed narrative diaries. Trustworthiness and ethical considerations were maintained throughout the study. The transcribed interviews, narrative diaries and field notes were analysed through open-coding. Recommendations focus on 1) empowering parents to participate in their child's care; 2) guiding nursing personnel to plan the discharge process; 3) including parents in the unit routine; 4) fostering a trusting relationship with parents; 5) promoting the communication of information; and 6) creating a therapeutic environment for parents.

Timed restricted feeding restores the rhythms of expression of the clock protein, Period2, in the oval nucleus of the bed nucleus of the stria terminalis and central nucleus of the amygdala in adrenalectomized rats.

Feeding schedules that limit food availability to a set time of day are powerful synchronizers of the rhythms of expression of the circadian clock protein Period 2 (PER2) in the limbic forebrain in rats. Little is known, however, about the mechanisms that mediate the effect of such timed restricted feeding (TRF) schedules on the expression of PER2. Adrenal glucocorticoids have been implicated in the circadian regulation of clock genes expression in peripheral tissues as well as in the control of the rhythms of expression of PER2 in certain limbic forebrain regions, such as the oval nucleus of the bed nucleus of the stria terminalis (BNSTov) and central nucleus of the amygdala (CEA) in rats. To study the possible involvement of glucocorticoids in the regulation of PER2 expression by TRF, we assessed the effect of adrenalectomy on TRF-entrained PER2 rhythms in the limbic forebrain in rats. Adrenalectomy selectively abolished the rhythms of PER2 in the BNSTov and CEA in normally fed rats, as previously shown, but had no effect on TRF-entrained PER2 rhythms in the same structures. These findings show that the effect of TRF on PER2 rhythms in the limbic forebrain is independent of adrenal glucocorticoids and demonstrate that the involvement of glucocorticoids in the regulation PER2 rhythms in the limbic forebrain is not only region specific, as previously shown, but also state dependent.

Differential regulation of the expression of Period2 protein in the limbic forebrain and dorsomedial hypothalamus by daily limited access to highly palatable food in food-deprived and free-fed rats.

Circadian clock genes are rhythmically expressed in many areas of the brain and body and are thought to underlie most endogenous circadian behaviors and physiological processes. Daily rhythms of clock gene expression throughout the brain and body are normally coordinated by the suprachiasmatic nucleus (SCN), but they are also strongly influenced by daily temporal restrictions of food availability. Here, we studied the effects of a daily restricted presentation of highly palatable complete meal replacement, chocolate Ensure Plus (Ensure) in food-deprived (restricted feeding, RF) and free-fed (restricted treat, RT) rats, on the expression of the clock protein, Period2 (PER2) in regions of the brain involved in motivational and emotional regulation; these include the oval nucleus of the bed nucleus of the stria terminalis (BNSTov), the central nucleus of the amygdala (CEA), the basolateral amygdala (BLA), the dentate gyrus (DG) and the dorsomedial hypothalamus (DMH). RF and RT rats consumed similar amounts of Ensure, but changes in the pattern of PER2 expression were seen only in the RF condition, suggesting that changes in PER2 expression in these regions are triggered by the daily alleviation of a negative metabolic state associated with RF and are independent of the positive incentive properties of the consumed substance, per se. In contrast, the expression of the immediate early gene, Fos, was increased in these regions by both RF and RT schedules, showing that signals concerning the incentive value of the consumed food reach these regions. No changes in either PER2 or Fos expression were observed in the SCN of RF or RT rats. These findings demonstrate that mechanisms leading to changes in the expression of PER2 and those affecting the induction of Fos under RF and RT are, at least in part, dissociable.

Analysis of mutations that uncouple transport from phosphorylation in enzyme IIGlc of the Escherichia coli phosphoenolpyruvate-dependent phosphotransferase system.

Mutations that uncouple glucose transport from phosphorylation were isolated in plasmid-encoded Escherichia coli enzyme IIGlc of the phosphoenolpyruvate-dependent phosphotransferase system (PTS). The uncoupled enzymes IIGlc were able to transport glucose in the absence of the general phosphoryl-carrying proteins of the PTS, enzyme I and HPr, although with relatively low affinity. Km values of the uncoupled enzymes IIGlc for glucose ranged from 0.5 to 2.5 mM, 2 orders of magnitude higher than the value of normal IIGlc. Most of the mutant proteins were still able to phosphorylate glucose and methyl alpha-glucoside (a non-metabolizable glucose analog specific for IIGlc), indicating that transport and phosphorylation are separable functions of the enzyme. Some of the uncoupled enzymes IIGlc transported glucose with a higher rate and lower apparent Km in a pts+ strain than in a delta ptsHI strain lacking the general proteins enzyme I and HPr. Since the properties of these uncoupled enzymes IIGlc in the presence of PTS-mediated phosphoryl transfer resembled those of wild-type IIGlc, these mutants appeared to be conditionally uncoupled. Sequencing of the mutated ptsG genes revealed that all amino acid substitutions occurred in a hydrophilic segment within the hydrophobic N-terminal part of IIGlc. These results suggest that this hydrophilic loop is involved in binding and translocation of the sugar substrate.