Does Recall after Sleep-Dependent Memory Consolidation Reinstate Sensitivity to Retroactive Interference?

Previous studies have shown that newly encoded memories are more resistant to retroactive interference when participants are allowed to sleep after learning the original material, suggesting a sleep-related strengthening of memories. In the present study, we investigated delayed, long-term effects of sleep vs. sleep deprivation (SD) on the first post-training night on memory consolidation and resistance to interference. On day 1, participants learned a list of unrelated word pairs (AB), either in the morning or in the evening, then spent the post-training night in a sleep or sleep deprivation condition, in a within-subject paradigm. On day 4, at the same time of day, they learned a novel list of word pairs (AC) in which 50% of the word pairs stemmed with the same word than in the AB list, resulting in retroactive interference. Participants had then to recall items from the AB list upon presentation of the “A” stem. Recall was marginally improved in the evening, as compared to the morning learning group. Most importantly, retroactive interference effects were found in the sleep evening group only, contrary to the hypothesis that sleep exerts a protective role against intrusion by novel but similar learning. We tentatively suggest that these results can be explained in the framework of the memory reconsolidation theory, stating that exposure to similar information sets back consolidated items in a labile form again sensitive to retroactive interference. In this context, sleep might not protect against interference but would promote an update of existing episodic memories while preventing saturation of the memory network due to the accumulation of dual traces.     

The effects of times of day on cognitive and visuo-motor performance efficiency

Twenty-four male graduate volunteers were administered a battery of psychological tests--critical flicker fusion (CFF; alternate and simultaneous), reaction time (simple and choice), memory (forward and backward), and associative recall--to ascertain their performance capability during the different times of day. Each subject performed the tests on two occasions, once in the morning (10:00 h) and on the second occasion in the evening (15:00 h), on two successive days, following a statistically balanced design. Analysis of variance reflected superior performance on reaction time (choice) and memory (backward) in the evening and on associative recall in the morning. While no such effects were noticeable on CFF, appreciable changes in performance with the decreasing brightness level of its light sources was observed. Further work in this direction on a variety of cognitive tests and sensory functions under various times (more than two times) throughout the day is suggested.     

Temporal trends in cardiovascular demand in EMS: Weekday versus weekend differences

Diagnosed cardiovascular disease has well-reported temporal patterns, with demand distribution peaks in the late morning and greater case numbers on Mondays and in winter. We aimed to report temporal patterns of presumptive cardiovascular disease cases as determined after emergency medical services (EMS) assessment and to characterize the demand distribution by day of the week. We conducted a secondary analysis of all Ambulance Victoria cases in metropolitan Melbourne (Victoria, Australia) between January 2008 and December 2011. Analyzed data included time of call, incident mechanism, location type, final assessment (paramedic “diagnosis”) and patient age. We employed Poisson’s regression to analyze case numbers and trigonometric regression to quantify distribution patterns. The 182?983 cases of presumptive cardiovascular disease observed during the study period constituted 15.2% of total demand. The median age of persons attended was 72 (IQR 57–82) and there was an almost even split between genders (51% female). Peak numbers of most cardiovascular case types occurred between 09:00 and 11:00; the only exception was acute pulmonary edema, which had peak case numbers at 06:00. Trigonometric regression showed distinct time of day distribution patterns, which did not alter by season. Although weekend day demand was lower than on Mondays, due to a different distribution pattern, these differences were not constant over the 24-hour period. There were up to 27% fewer cases at 09:00 and up to 2.8% more cases at 01:00 on weekends compared to Mondays. We have shown that examination of presumptive cardiovascular disease using not only case counts but also demand distribution patterns allows for a greater understanding of ambulance demand. Monday might be the most frequent day for cardiovascular cases but different patterns of demand occur on weekends. Increased knowledge of when different types of cases are most likely to occur will help inform EMS planning, including paramedic capacity and resources.     

Prostaglandin output from the early pregnant rat uterus superfused in vitro, and the effect of A23187 and trifluoperazine

The outputs of prostaglandin (PG) E-2 and 6-oxo-PGF-1 alpha from the early pregnant rat uterus superfused in vitro were significantly higher (P less than 0.05) on Day 4 (09:00-10:00 h) and Day 5 (14:00-15:00 h) than on Day 2 (09:00-10:00 h) and Day 5 (14:00-15:00 h). PGF-2 alpha output was significantly higher (P less than 0.05) only on Day 5 (09:00-10:00 h). PGE-2 was the major PG released at all times, although the amounts of PGF-2 alpha and/or 6-oxo-PGF-1 alpha released were often only slightly less. These findings are consistent with uterine PGs having a role in implantation in the rat. A23187 stimulated 6-oxo-PGF-1 alpha output and, except on Day 4 (09:00-10:00 h), PGF-2 alpha output at all times studied. A23187 had little effect on PGE-2 output. The greatest stimulatory effect of A23187 on 6-oxo-PGF-1 alpha and PGF-2 alpha outputs occurred on Day 5 (09:00-10:00 h), which is the day of highest uterine PGH-2 synthetase activity. These increases in response to A23187 were prevented by trifluoperazine (100 microM), a calmodulin antagonist. Trifluoperazine had no inhibitory effect on the high basal output of PGs on Day 5 (09:00-10:00 h), but caused a small increase in uterine PG output.     

基于就诊流量监测的门诊资源合理分配研究

目的 通过历史流量数据及流量监测系统,对医院门诊流量情况进行分析,为门诊人力资源合理分配提供依据。 方法 应用时间序列数据季节指数分析法对医院历史门诊流量数据按月份、周和每日不同时间段流量进行分析,并对流量监测系统的历史数据进行统计分析。 结果 门诊流量3、5、7、11、12月份较大,1、2月份较少;一周中周一至周三流量较大,周四、周五流量较少;一天中早上8：00～10：00流量较大,呈明显就诊高峰,下午14：00～16：00为就诊低峰。 结论 医院门诊流量在一年的不同月份、每周的不同天次、每日的不同时间段都有不同的变化规律。     

Involvement of prostaglandins in LH-induced superovulation in the cyclic hamster

Osmotic minipumps containing 400 micrograms ovine LH were inserted subcutaneously (sc) on day 1 (estrus) at 09:00-10:00h of the cycle in the hamster. This treatment induced increased ovarian blood flow by day 3 and superovulation of 30.0 +/- 1.4 ova at the next estrus compared to controls (16.5 +/- 0.8 ova). The continuous infusion of LH throughout the cycle increased prostaglandin F (PGF) and decreased prostaglandin E (PGE) in the growing follicles destined to ovulate and suppressed a day 3 increase in PGF concentrations in the nonluteal ovarian remnant devoid of the larger follicles. Indomethacin, a cyclooxygenase inhibitor, given sc (2 or 4 mg regimens) at 12:00-14:00h on days 1 and 2, at 09:00h and 17:00h on day 3 and at 09:00h on day 4 of the cycle to LH-infused and saline treated animals suppressed ovarian prostaglandin levels, prevented the superovulation and prevented the increased ovarian blood flow. Exogenous PGF2 alpha or PGE2 restored the superovulatory effect of LH infusion in the presence of indomethacin. The results suggest that the superovulation in response to continuous LH infusion may be mediated in part by prostaglandins via altered ovarian blood flow.     

Variation in epinephrine and cortisol excretion rates associated with behavior in an Australian Aboriginal community

Urinary epinephrine and cortisol hormone output in a remote Australian Aboriginal community was on average about twice as high in those individuals measured on a Thursday or Friday as those measured at the beginning of the next week (Monday or Tuesday). Diastolic blood pressure was about 6 mm Hg higher in the Thursday–Friday group, but the difference in mean systolic blood pressure between the day groups does not reach statistical significance. These physiological differences are associated with a marked dichotomy in behavior in the two time periods: on the first 2 days, virtually all adults were involved in intense gambling activity for large stakes, but this was not a feature of the latter period. This behavior pattern occurs on a regular weekly basis. If substantiated by longitudinal studies, this phenomenon may provide an additional link between human behavior and a poor health profile mediated via the physiological consequences of high stress hormone output. Am J Phys Anthropol 106:249–253, 1998. © 1998 Wiley-Liss, Inc.     

莫达非尼对睡眠剥夺条件下工作记忆的影响

目的:观察在睡眠剥夺条件下莫达非尼对工作记忆的改善作用,为此药在我军的应用策略提供实验依据。方法:18名健康男性志愿者,在两次睡眠剥夺实验中交叉服用莫达非尼和安慰剂,睡眠剥夺时间从第一天的07:00到第3d的07:00,并于第二天的0:00、12:00和第三天的0:00分别服用莫达非尼100mg或安慰剂。采用随机双盲设计给药,并在第一天的07:00、第二天的02:00和14:00以及第三天的02:00和07:00安排工作记忆测验。结果:工作记忆测验中,两组的反应时和正确率均有统计学差异(P<0.01),莫达非尼组的反应时要快于安慰剂组,正确率也要高于安慰剂组。莫达非尼对工作记忆的改善效果随着睡眠剥夺时间的延长而更趋明显。结论:莫达非尼对睡眠剥夺条件下个体的工作记忆有改善作用,是较为理想的睡眠剥夺对抗药物。     

少年游泳运动员冬训期间HbA_2百分含量的规律性变化

 本研究用聚丙烯酰胺凝胶垂直板电泳,双波长扫描仪对少年游泳运动员的HbA_2百分含量进行测定。发现大运动量训练对HbA_2水平是有影响的。经六天训练(星期二、五为大运动量训练),星期日休息一天,次周的星期一晨HbA_2百分含量升高,星期二大运动量训练后的次日晨HbA_2百分含量显著下降。运动性贫血的运动员,其HbA_2百分含量一周中的变化趋势与正常运动员相似,但HbA_2百分含量比正常运动员高。     

Specific memory effects of Ginkgo biloba extract EGb 761 in middle-aged healthy volunteers

Introduction

Recent reviews showed that Ginkgo biloba extract EGb 761¹ is effective to enhance performance in patients with cognitive impairment (e.g., dementia). The aim of this study was to investigate the effects of EGb 761 on memory and the specificity of such effects on distinct memory functions in middle-aged healthy volunteers.

Methods

A total of 188 healthy subjects aged 45-56 years were randomised to receive EGb 761 (240 mg once daily) or placebo for 6 weeks. Outcome measures were the change in memory performance in a demanding standardised free recall paradigm (list of appointments) and a less demanding standardised recognition test (driving-route). Based on previous findings we predicted superiority of EGb 761 in recall testing. Specificity in effects was assessed by separating immediate vs. delayed and quantitative vs. qualitative free recall measures.

Results

After 6 weeks, EGb 761-treated subjects improved significantly in quantity of recall, i.e., the number of correctly recalled appointments (drug-placebo differences: p = 0.038 for immediate and p = 0.008 for delayed recall). Effects on qualitative recall performance (ratio of false to correct items) were similar (drug-placebo differences: p = 0.092 for immediate and p = 0.010 for delayed recall). No superiority of Ginkgo was evident in another everyday memory test which asked for recognition of a driving route (drug-placebo differences: p > 0.10). The incidence of adverse events was low and not significantly different between treatment groups.

Discussion

EGb 761 (240 mg once daily) improves free recall of appointments in middle-aged healthy volunteers, which requires high demands on self-initiated retrieval of learned material. This function is known to be sensitive to normal aging, i.e., reduced in healthy middle-aged subjects. No effects are seen in a less demanding everyday memory task which does not tap this critical function. This ties in with previous studies which found specific patterns of benefit from EGb 761 in demanding cognitive tasks.     

Acute effects of unilateral ovariectomy on follicular development in the cyclic hamster

Hamsters were hemispayed at 09:00 h on Day 3 of the cycle (Day 1 equal to ovulation) and were killed 1 h after injection of [3H]thymidine at 09:00, 12:00, 17:00 or 22:00 h. Unilateral ovariectomy had no effect on the number of Stage 1 or Stage 2 follicles, but there were significantly fewer Stage 3 follicles between 10:00 and 13:00 h. This decrease was not encountered in intact hamsters and was reflected in an increase in the number of Stage 6 (antral) follicles. At 13:00 h there was no difference in the number of atretic follicles between the experimental and control groups. It is concluded that preantral follicles with 6-7 layers of granulosa cells were recruited within 4 h after unilateral ovariectomy and transformed into antral follicles.     

Bacterial water quality and network hydraulic characteristics: a field study of a small, looped water distribution system using culture-independent molecular methods

Aims: To determine the spatial and temporal variability in the abundance, structure and composition of planktonic bacterial assemblages sampled from a small, looped water distribution system and to interpret results with respect to hydraulic conditions. Methods and Results: Water samples were collected from five sampling points, twice a day at 06:00 h and 09:00 h on a Monday (following low weekend demand) and a Wednesday (higher midweek demand). All samples were fully compliant with current regulated parameter standards. This study did not show obvious changes in bacterial abundance (DAPI count) or community structure Denaturing gradient gel electrophoresis analysis with respect to sample site and hence to water age; however, the study did show temporal variability with respect to both sampling day and sample times. Conclusions: Data suggests that variations in the bacterial assemblages may be associated with the local system hydraulics: the bacterial composition and numbers, over short durations, are governed by the interaction of the bulk water and the biofilm influenced by the hydraulic conditions. Significance and Impact of the Study: This study demonstrates general stability in bacterial abundance, community structure and composition within the system studied. Trends and patterns supporting the transfer of idealized understanding to the real world were evident. Ultimately, such work will help to safeguard potable water quality, fundamental to public health.     

Delaying and Extending Sleep During Weekends: Sleep Recovery or Circadian Effect?

There is a well-known tendency to delay and prolong our sleep during weekends (Saturday and Sunday), with an advance and reduction of sleep during workdays (Monday to Friday). The objective of this work was to determine if the changes of sleep during weekends are produced by a partial sleep deprivation or a lack of entraining of circadian rhythms to an advanced phase, during workdays. The subjects were 52 undergraduate female students, mean age = 17.5 years, SD = 1.32. All students attended school following a regular schedule, from Monday to Friday. Two groups of students were studied: one attended school from 07:00 to 12:00 h (morning group, n = 30); the other attended school from 14:00 to 18:00 (afternoon group, n = 22). None of the students worked or was engaged in other activity with a fixed schedule. All kept a sleep-wake diary for 2 weeks, in which they recorded their bedtimes, wakeup times, and sleep-onset latencies. The morning group delayed 47.4 min [t(29) = 4.72, p < 0.0001] and prolonged their sleep 118.2 min [t(29) = 9.4, p < 0.0001] during weekends. Although the afternoon group had the opportunity to maintain a delayed phase and a long sleep time throughout the week, they delayed their bedtime by 24 min [t(21) = 2.99, p < 0.01] during weekends, without changing their sleep duration. The findings suggest that the prolonged sleep during weekends is due to reduction of sleep during workdays, whereas the delay of bedtime seems to be associated with a tendency of the human circadian system to maintain a delayed phase     

Circadian response of annual weeds to glyphosate and glufosinate

Five field experiments were conducted in 1998 and 1999 in Minnesota to examine the influence of time of day efficacy of glyphosate [N-(phosphonomethyl)glycine] and glufosinate [2-amino-4-(hydroxymethyl-phosphinyl)butanoic acid] applications on the control of annual weeds. Each experiment was designed to be a randomized complete block with four replications using plot sizes of 3×9 m. Glyphosate and glufosinate were applied at rates of 0.421 kg ae/ha and 0.292 kg ai/ha, respectively, with and without an additional adjuvant that consisted of 20% nonionic surfactant and 80% ammonium sulfate. All treatments were applied with water at 94 L/ha. Times of day for the application of herbicide were 06:00h, 09:00h, 12:00h, 15:00h, 18:00h, 21:00h, and 24:00h. Efficacy was evaluated 14 d after application by visual ratings. At 14 d, a circadian response to each herbicide was found, with greatest annual weed control observed with an application occurring between 09:00h and 18:00h and significantly less weed control observed with an application at 06:00h, 21:00h, or 24:00h. The addition of an adjuvant to both herbicides increased overall efficacy, but did not overcome the rhythmic time of day effect. Results of the multiple regression analysis showed that after environmental temperature, time of day was the second most important predictor of percent weed kill. Thus, circadian timing of herbicide application significantly influenced weed control with both glyphosate and glufosinate.     

Weekend Eating in the United States Is Linked with Greater Energy,Fat, and Alcohol Intake

Objectives: To determine if macronutrient consumption for the U.S. population is greater on weekend days than weekdays. Research Methods and Procedures: The nationally representative 1994 to 1996 Continuing Survey of Food Intakes by Individuals was used for this analysis. Dietary intake was assessed using two independent days of dietary recall data. Ordinary least squares multivariate analysis was used to analyze dietary outcome variables to explore the effect of weekend day vs. weekday intake. Results: This study's results indicate that statistically significant dietary intake differences occur for different days of the week but not for all age groups—nor for all nutrients. The average American, 2 years and older, consumes 82 kcal more per day on each weekend day (Friday through Sunday) than they do on weekdays (Monday through Thursday). These overall increases in dietary intake are significant for the overall sample and are largest for the 19‐ to 50‐year‐old age group; among this age group, the weekend day increase (vs. weekday) is 115 kcal/d. The increased proportions of energy from fat and alcohol consumed on weekends are greater for this adult age group by 0.7% and 1.4%, respectively, whereas the proportion of energy from carbohydrate decreases 1.6%. Discussion: The effects of weekend days on nutrient intake are substantial and should be considered in future clinical and population‐based interventions and in dietary monitoring and research in the U.S.     

Reduction in endometrial neutrophils in proximity to implanting rat blastocysts.

An antiserum to rat neutrophils was raised and used to follow the distribution of endometrial neutrophils during the peri-implantation period. Uteri from four pregnant and four pseudopregnant rats killed at 14:00, 17:00, 20:30 and 23:00 h on day 5 of pregnancy and 09:00 h on day 6 were sectioned. Four sections from each of four implantation sites and four intersites from each rat were immunostained. There was wide variability among rats in the number of endometrial neutrophils, but a nested analysis of variance showed significantly fewer neutrophils at implantation sites than at intersites from 20:30 h onwards. This difference was primarily due to the presence of more neutrophils in intersite regions of the endometrium. The results from this study do not support a role for neutrophils in the implantation-associated increase in microvascular permeability or decidualization in rats.     

Weekly Changes in Psychophysiological Variables of 8- to 10-Year-Old School Girls

Three groups of schoolgirls 8, 9, and 10 years of age, respectively, self assessed sleep onset/offset and duration, as well as oral temperature and a set of cognitive measures, at school at 09:00, 11:00, 14:00, and 16:00 h on Mondays, Tuesdays, Thursdays, and Fridays (and/or Saturday) for 2 consecutive weeks (spring 1987 and 1989). The scores of a letter cancellation test exhibited neither daily nor weekly temporal variation at the age of 8 years [analysis of variance (ANOVA), p > 0.05]. In contrast, in the 10-year-olds, changes as a function of both time of day (peak time 14:00–16:00 h) and day of week (peak day Tuesday-Friday) were substantiated. Moreover, the time of best performance on the letter cancellation test varied systematically according to the day of the week (ANOVA, p = 0.000). Day of the week changes in the observed duration of sleep, self-rated fatigue, drowsiness, and attention changes were not detected in any of the age groups. It is hypothesized that temporal performance variations in the girls during the 7-day period was age related.     

Changes in the density of peripheral benzodiazepine binding sites in genital organs of the female rat during the oestrous cycle

The affinity and the density of peripheral-type benzodiazepine binding sites (PBzS) in tissues from the genital organs of female rats were studied during the oestrous cycle. When comparing PBzS density on the day of oestrus to PBzS density on the day of pro-oestrus, a significant increase was observed in the ovary (1.9-fold), oviduct (2.4-fold) and uterus (1.7-fold), but not in the kidney. Serum oestradiol also increased to a maximum on the day of pro-oestrus. The ovarian and uterine PBzS density and serum concentrations of oestradiol and progesterone were measured every 8 h between the days of dioestrus and pro-oestrus. Ovarian and uterine PBzS density increased to a maximal value at 01:00 and 09:00 h, respectively, on the day of pro-oestrus. However, a significant increase in PBzS density occurred in the ovary (P less than 0.02) and uterus (P less than 0.001) at 09:00 h on the day of pro-oestrus as compared to 09:00 h on the day of dioestrus. These changes were associated with an increase in serum oestradiol and progesterone concentrations. The affinity of PBzS in all tissues examined remained unaltered during the oestrous cycle. This study demonstrates that changes associated with the oestrous cycle occur in the density of PBzS in various genital organs.     

Effects of hemodialysis on serum lipids and phospholipids of end-stage renal failure patients

There is a link between diabetes and oxidative stress. Hyperglycaemia leads to free radical generation and alterations of endogenous antioxidants. Our aim is to study the effect of orally administered L-tryptophan (TRP), the melatonin precursor, an endogenous antioxidant, on circulating levels of glycaemia, insulin and melatonin, and on the superoxide dismutase and catalase antioxidant systems in non-diabetic (ND) and type 2 diabetic (n5-STZ) male Wistar rats. At 19:30 every day for 15 days, TRP (125 mg/kg body weight) was administered orally. At 09:00 every two days the glycaemia was measured and every day the intake of food and water was recorded. At the beginning and end of treatment (at 09:00; 21:00; 02:00) plasma insulin and melatonin levels were measured, and (at 09:00) the enzymatic activities of catalase and superoxide dismutase (SOD) in erythrocytes were also measured. Glycaemia values were greater (p < 0.01) in n5-STZ rats than in ND rats, while insulin levels were lower (p < 0.05) at all times studied and these parameters were not altered by the TRP administration. Melatonin levels at 02:00 were lower in n5-STZ than in ND rats (p < 0.05). The TRP administration did not modify the circulating melatonin levels in ND rats, but raised (p < 0.01) the levels at 02:00 in the treated n5-STZ group. In ND rats after TRP administration there was a decline in catalase activity (p < 0.05), while in n5-STZ rats there was a rise (p < 0.01) at the end of treatment. However, there were no significant changes in SOD activity. There was increased food intake (g/day) in the treated n5-STZ group (p < 0.01). In conclusion, the oral administration of TRP did not modify glycaemia or insulinaemia levels, but raised melatonin levels in diabetic rats at 02:00, lowered catalase activity in ND rats but raised it in n5-STZ rats, and increased food intake in n5-STZ rats.     

Heart Rate Recovery Predicts Memory Performance in Older Adults

The current study examined cardiovascular reactivity and recovery during memory testing in a sample of 28 younger and 28 older adults. Heart rate (HR) levels were measured before, during, and after a memory test (word list recall). Contrary to prediction, older adults did not have a blunted cardiovascular response to memory tasks compared to younger adults. Word list recall performance was predicted by both Age and an Age × HR recovery interaction. As expected, younger adults performed better on the word list task than older adults. In addition, older adults with better posttest HR recovery performed significantly better than older adults with poor posttest HR recovery, whereas HR recovery differences in younger adults were inconsequential. These relationships were not affected by subjective appraisals of anxiety and task difficulty. Overall, cardiac dysregulation, seen here as low HR recovery, represents an important, potentially modifiable, factor in memory performance in older adults. In addition to being beneficial to overall health, interventions designed to help older adults regulate their HR responses may help offset certain memory declines.