Independent and Joint Associations of Physical Activity and Sleep on Mental Health Among a Global Sample of 200,743 Adults

BACKGROUND

Previous research has demonstrated that both sleep and physical activity (PA) are independently associated with various indicators of mental health among adults. However, their joint contribution to mental health has received limited attention. The present study used cross-sectional data from the Mental Health Million Project to examine the independent and joint effects of sleep and PA on mental health among a global sample of adults, and whether these effects differ among individuals receiving mental health treatment.

METHOD

The sample included 200,743 participants (33.1% young adults, 45.6% middle-aged adults, 21.3% older adults; 57.6% females, 0.9% other) from 213 countries, territories, and archipelagos worldwide that completed a comprehensive 47-item assessment of mental health including both problems (i.e., ill-being) and assets (i.e., well-being): the Mental Health Quotient. Participants also reported their weekly frequency of PA and adequate sleep, and mental health treatment status. A series of generalized linear mixed models were computed.

RESULTS

Independent dose-response associations were observed, whereby greater amounts of PA and adequate sleep were each associated with better mental health. In addition, a synergistic interaction was observed in which the positive correlation of PA with mental health was strengthened with greater frequency of adequate sleep. These benefits were less pronounced among adults receiving mental health treatment.

CONCLUSION

While findings suggest sleep can help to offset the negative influence of a physically inactive lifestyle (and vice versa), our results point to a "more is better" approach for both behaviors when it comes to promoting mental health.

Overnight exposure to pink noise could jeopardize sleep-dependent insight and pattern detection

Accumulated evidence from the past decades suggests that sleep plays a crucial role in memory consolidation and the facilitation of higher-level cognitive processes such as abstraction and gist extraction. In addition, recent studies show that applying pink noise during sleep can further enhance sleep-dependent memory consolidation, potentially by modulating sleep physiology through stochastic resonance. However, whether this enhancement extends to higher cognitive processes remains untested. In this study, we investigated how the application of open-loop pink noise during sleep influences the gain of insight into hidden patterns. Seventy-two participants were assigned to three groups: daytime-wake, silent sleep, and sleep with pink noise. Each group completed the number reduction task, an established insight paradigm known to be influenced by sleep, over two sessions with a 12-h interval. Sleep groups were monitored by the DREEM 3 headband in home settings. Contrary to our prediction, pink noise did not induce an increase in insight compared to silent sleep and was statistically more similar to the wake condition despite evidence for its typical influence on sleep physiology. Particularly, we found that pink noise limited the time spent in the initial cycle of N1 just after sleep onset, while time spent in N1 positively predicted insight. These results echo recent suggestions that the time in the initial cycle of N1 plays a critical role in insight formation. Overall, our results suggest that open-loop pink noise during sleep may be detrimental to insight formation and creativity due to the alterations it causes to normal sleep architecture.

Re-evaluating two popular EEG-based mobile sleep-monitoring devices for home use

Mobile sleep-monitoring devices for consumer use have been gaining traction as a possible replacement to traditional polysomnography recordings. Such devices potentially offer detailed sleep analysis without requiring the use of designated sleep labs operated by qualified technicians. However, the accuracy of these mobile devices is often not sufficiently evaluated by independent researchers. Here, we compared the performance of two popular mobile electroencephalogram-based systems, the DREEM 3 headband and the Zmachine Insight+. Both devices can be used by participants with minimal training, and provide detailed sleep scoring previously validated by the respective developers in comparison to the gold-standard of polysomnography. A total of 25 participants used both devices simultaneously to record their sleep for two consecutive nights while also keeping a sleep log. We compared the devices' performance, both with each other and in relation to the sleep logs, using several well-known sleep metrics. In addition, we developed a Bayesian lower limit for the devices' expected epoch-by-epoch sleep stage agreement based on their previously published agreement with polysomnography, and compared it with our empirical findings. Results suggest that the Zmachine tends to overestimate periods of wakefulness, likely at the expense of N1/N2 detection, whereas the DREEM tends to underestimate wakefulness and mistake it for N1/N2, with both results more pronounced than previously reported. In addition, we found that the agreement between the devices tends to increase from night 1 to night 2. We formulate several recommendations for how best to use these devices based on our results.

Ultra-sensitive troponin-I and incident coronary heart disease, stroke, heart failure, cardiac arrhythmias, arterial aneurysms and venous thromboembolism hospitalizations

Background

Cardiac troponin I (cTnI) as measured by high-sensitive assays has been related to incident cardiovascular disease events (CVD) in the community. With the advent of ultra-sensitive assays, it is now possible to detect troponin I at very low concentration, far below the classical threshold of 1.9 pg/mL. However, the clinical relevance of these low concentrations for predicting CVD is largely unknown.

Purpose

To examine the association of cTnI as low as 0.013 pg/mL with incident cardiovascular disease events (CVDs) in the primary prevention setting.

Methods

cTnI was analyzed in the baseline plasma (2008–2012) of CVD free volunteers from the Paris Prospective Study III using for the first time a novel ultra-sensitive immunoassay (Simoa Troponin-I 2.0 Kit, Quanterix, Lexington) with a limit of detection (LOD) of 0.013 pg/mL. Incident CVD hospitalizations for coronary heart disease, stroke, arrhythmias, venous thromboembolism, arterial aneurysms and heart failure were validated by critical review of the hospital records. Hazard ratios were estimated per log-transformed standard deviation (SD) increase of cTnI in Cox models using age as the time scale. The added value (gain in discriminatory capacity) of cTnI for CVD risk prediction was examined by calculating the Harell's C-index boostraped difference of the SCORE 2 risk model with and without cTnI.

Results

There were 9503 CVD free participants (40% women) aged 59.6 (6.3) years at baseline. cTnI was detected in 99.6% of the participants (median value = 0.63 pg/mL, interquartile range [IQR] 0.39–1.09). After a median follow-up of 8.34 years (IQR, 8.0–10.07), 516 participants suffered 612 events. In fully-adjusted analysis, higher cTnI (per 1 SD increase of log cTnI) was significantly associated with CVD events combined (n=516, HR= 1.21; 1.06; 1.39). In univariate Cox analysis and compared to each single established risk factor, cTnI had the highest discrimination capacity for incident CVD events (C-index=0.6349) (Figure 1). Adding log cTnI to the SCORE 2 algorithm increased significantly albeit moderately discriminatory capacity (C-index 0.698 vs. 0.685; boostraped C index difference: 0.0135 (95% CI: 0.0131; 0.0138)).

Conclusion

cTnI concentrations as measured by a novel ultra-sensitive immunoassay is associated with a significant increased risk of incident CVD events in the primary prevention setting.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): ANR: French National Research AgencyEurope: Horizon 2020

Sleep Facilitates Extraction of Temporal Regularities With Varying Timescales

Evidence suggests that memory consolidation is facilitated by sleep, both through the strengthening of existing memories and by extracting regularities embedded in those memories. We previously observed that one sleep stage, Slow-Wave sleep (SWS), is particularly involved in the extraction of temporal regularities. We suggested that this attribute can naturally stem from the time-compressed memory replay known to occur in the hippocampus during SWS. A prediction coming out of this “temporal scaffolding” hypothesis is that sleep would be especially influential on extraction of temporal regularities when the time gap between the events constituting the regularities is shortish. In this study, we tested this prediction. Eighty-three participants performed a cognitive task in which hidden temporal regularities of varying time gaps were embedded. Detecting these regularities could significantly improve performance. Participants performed the task in two sessions with an interval filled with either wake or sleep in between. We found that sleep improved performance across all time gaps and that the longer the gap had been, the smaller was the improvement across both sleep and wake. No interaction between sleep and gap size was observed; however, unlike sleeping participants, awake participants did not exhibit any further performance improvement for the long gaps following the interval. In addition, across all participants, performance for the long gaps was associated with the development of conscious awareness to the regularities. We discuss these results in light of the temporal scaffolding hypothesis and suggest future directions to further elucidate the mechanisms involved.

Sleep to remember, sleep to forget: Rapid eye movement sleep can have inverse effects on recall and generalization of fear memories

Rapid Eye Movement (REM) sleep has been shown to modulate the consolidation of fear memories, a process that may contribute to the development of Post-Traumatic Stress Disorder (PTSD). However, contradictory findings have been reported regarding the direction of this modulation and its differential effects on recall versus generalization. In two complementary experiments, we addressed this by employing sleep deprivation protocols together with a novel fear-conditioning paradigm that required the discrimination between coexisting threat and safety signals. Using skin conductance responses and functional imaging (fMRI), we found two opposing effects of REM sleep: While REM impaired recall of the original threat memories, it improved the ability to generalize these memories to novel situations that emphasized the discrimination between threat and safety signals. These results, as well as previous findings in healthy participants and patients diagnosed with PTSD, could be explained by the degree to which the balance between threat and safety signals for a given stimulus was predictive of threat. We suggest that this account can be integrated with contemporary theories of sleep and fear learning, such as the REM recalibration hypothesis.

Infection à SARS-CoV-2 et biomédicaments : une étude multicentrique française de 7808 patients

Introduction

Les formes sévères d’infection à COVID-19 sont liées à une importante réponse inflammatoire. Certains biomédicaments (BM) sont en cours d’évaluation dans des essais thérapeutiques avec pour rationnel cet orage cytokinique. À l’inverse, nous pouvons nous interroger sur le risque d’infections à COVID-19 chez les patients sous BM au long cours. L’objectif principal de notre étude était de déterminer l’impact de la prise d’un BM sur le taux d’hospitalisation, de passage en réanimation (ICU) et de décès chez les patients sous BM atteints d’une infection à COVID-19.

Matériels et méthodes

Étude de cohorte rétrospective multicentrique à partir des données médico-administratives de l’Entrepôt de Données de Santé (EDS) de l’APHP. L’ensemble des patients recevant un BM (anti-TNF, anti-IL-12/23, anti-IL-17 ou anti-intégrine) étaient inclus. Les événements d’intérêt étaient la survenue d’une hospitalisation, d’un séjour en ICU ou d’un décès dans le cadre d’une infection à COVID-19 (confirmée par RT-PCR ou TDM thoracique) entre le 01/02 et le 22/04/20. Le risque d’hospitalisation/ICU/décès était évalué selon la méthodologie du Ratio de Morbidité/Mortalité Standardisé (SMR) en calculant le rapport entre le nombre observé et le nombre attendu. Le nombre attendu d’hospitalisation/ICU/décès était calculé en appliquant le taux d’hospitalisation/ICU/décès à COVID-19 de la population d’Ile-de-France (par tranche d’âge de 20 ans et par sexe) au nombre de personnes sous BM dans la sous-classe correspondante de la même source de données (données EDS de l’APHP).

Résultats

Un total de7808 patients (âge médian 45 ans, 51 % de femmes) étaient inclus ; dont 48 avec un diagnostic d’infection à COVID-19 : 19 (40 %) hospitalisés, 4 (8 %) en ICU et 1 décès. En comparaison avec la population d’Ile-de-France, les taux d’hospitalisation et d’ICU étaient significativement élevés chez les patients sous BM avec SMR 2,19, IC95 % 1,32-3,42, p < 0,001 et SMR 6,04, IC95 % 1,62-15,45, p < 0,001 respectivement, significativement observés chez les [20-40[. Cependant, une analyse post-hoc suggérait que les SMR d’hospitalisation et d’ICU étaient surestimés, un retour aux compte-rendus mettant en évidence une poussée de la pathologie sous-jacente comme principal motif d’hospitalisation chez les [20-40[et non une infection à COVID-19 nécessitant une hospitalisation ou un passage en ICU. Aucun sur-risque de mortalité était mis en évidence.

Discussion

À partir d’une large base de données, notre étude a permis de confirmer que les taux d’hospitalisation, de passage en réanimation et de mortalité n’étaient pas augmentés chez les patients sous BM. Nos résultats sont concordants avec les différentes études publiées dans la littérature (Haberman et al., Favalli et al. ou Sanchez-Piedra et al.).

Conclusion

Ces résultats plaident pour un maintien des BM en période d’épidémie du virus COVID-19 pour éviter la rechute des pathologies inflammatoires de fond.

Direct 24-Hour Presumptive Enumeration of Escherichia coli 0157:H7 in Foods Using Hydrophobic Grid Membrane Filter Followed by Serological Confirmation: Collaborative Study

Fifteen laboratories took part in a collaborative study to validate a method for enumerating Escherichia coli 0157:H7. The method is based on use of a hydrophobic grid membrane filter and consists of 24 h presumptive enumeration on SD-39 Agar and serological confirmation to yield a confirmed E. coli 0157:H7 count. Six food products were analyzed: pasteurized apple cider, pasteurized 2% milk, cottage cheese, cooked ground pork, raw ground beef, and frozen whole egg. The test method produced significantly higher confirmed count results than did the reference method for milk, pork, and beef. Test method results were numerically higher than but statistically equivalent to reference method results for cheese, cider, and egg. The test method produced lower repeatability and reproducibility values than did the reference method for most food/inoculation level combinations and values very similar to those of the reference method for the remaining combinations. Overall, 94% of presumptive positive isolates from the test method were confirmed serologically as E. coli 0157:H7, and 98% of these were also biochemically typical of E. coli 0157:H7 (completed test). Corresponding rates for the reference method were 69 and 98%, respectively. On the basis of the results of this collaborative study and the precollaborative study that preceded it, it is recommended that this method be adopted official first action for enumeration of E. coli 0157:H7 in meats, poultry, dairy foods, infant formula, liquid eggs, mayonnaise, and apple cider

One-Shot Tagging During Wake and Cueing During Sleep With Spatiotemporal Patterns of Transcranial Electrical Stimulation Can Boost Long-Term Metamemory of Individual Episodes in Humans

Targeted memory reactivation (TMR) during slow-wave oscillations (SWOs) in sleep has been demonstrated with sensory cues to achieve about 5-12% improvement in post-nap memory performance on simple laboratory tasks. But prior work has not yet addressed the one-shot aspect of episodic memory acquisition, or dealt with the presence of interference from ambient environmental cues in real-world settings. Further, TMR with sensory cues may not be scalable to the multitude of experiences over one's lifetime. We designed a novel non-invasive non-sensory paradigm that tags one-shot experiences of minute-long naturalistic episodes in immersive virtual reality (VR) with unique spatiotemporal amplitude-modulated patterns (STAMPs) of transcranial electrical stimulation (tES). In particular, we demonstrated that these STAMPs can be re-applied as brief pulses during SWOs in sleep to achieve about 10-20% improvement in the metamemory of targeted episodes compared to the control episodes at 48 hours after initial viewing. We found that STAMPs can not only facilitate but also impair metamemory for the targeted episodes based on an interaction between pre-sleep metamemory and the number of STAMP applications during sleep. Overnight metamemory improvements were mediated by spectral power increases following the offset of STAMPs in the slow-spindle band (8-12 Hz) for left temporal areas in the scalp electroencephalography (EEG) during sleep. These results prescribe an optimal strategy to leverage STAMPs for boosting metamemory and suggest that real-world episodic memories can be modulated in a targeted manner even with coarser, non-invasive spatiotemporal stimulation.

Rappaport-Vassiliadis Medium for Recovery of Salmonellaspp. from Low Microbial Load Foods: Collaborative Study

Twenty-three laboratories participated in a collaborative study to compare the relative effectiveness of Rappaport-Vassiliadis (RV) medium incubated at 42°C, selenite cystine (SC) broth (35°C), and tetrathionate (TT) broth (35 and 43°C) for recovery of Salmonella from the following foods with a low microbial load: dried egg yolk, dry active yeast, ground black pepper, guar gum, and instant nonfat dry milk. For dry active yeast, lauryl tryptose (LT) broth, incubated at 35°C, was used instead of SC broth. All of the foods were artificially inoculated with single Salmonella serovars, that had been lyophilized before inoculation, at high and low target levels of 0.4 and 0.04 colony forming units/g food, respectively. For analysis of 870 test portions, representing all of the foods except yeast, 249 Salmonella-positive test portions were detected by RV medium, 265 by TT broth (43°C), 268 by TT broth (35°C), and 269 by SC broth (35°C). For analysis of 225 test portions of yeast, 79 Salmonella-positive test portions were detected by RV medium, 79 by TT broth (43°C), 84 by TT broth (35°C), and 68 by LT broth (35°C). RV medium was comparable to, or even more effective than, the other selective enrichments for recovery of Salmonella from all of the foods except guar gum. It is recommended that RV (42°C) and TT (35°C) be used with foods that have a low microbial load, except for guar gum for which SC (35°C) and TT (35°C) are recommended.

Sleep and the extraction of hidden regularities: A systematic review and the importance of temporal rules

As part of its role in memory consolidation, sleep has been repeatedly identified as critical for the extraction of regularities from wake experiences. However, many null results have been published as well, with no clear consensus emerging regarding the conditions that yield this sleep effect. Here, we systematically review the role of sleep in the extraction of hidden regularities, specifically those involving associative relations embedded in newly learned information. We found that the specific behavioral task used in a study had far more impact on whether a sleep effect was discovered than either the category of the cognitive processes targeted, or the particular experimental design employed. One emerging pattern, however, was that the explicit detection of hidden rules is more likely to happen when the rules are of a temporal nature (i.e., event A at time t predicts a later event B) than when they are non-temporal. We discuss this temporal rule sensitivity in reference to the compressed memory replay occurring in the hippocampus during slow-wave-sleep, and compare this effect to what happens when the extraction of regularities depends on prior knowledge and relies on structures other than the hippocampus.

Individual Differences in Slow-Wave-Sleep Predict Acquisition of Full Cognitive Maps

Accumulating evidence suggests that sleep, and particularly Slow-Wave-Sleep (SWS), helps the implicit and explicit extraction of regularities within memories that were encoded in a previous wake period. Sleep following training on virtual navigation was also shown to improve performance in subsequent navigation tests. Some studies propose that this sleep-effect on navigation is based on explicit recognition of landmarks; however, it is possible that SWS-dependent extraction of implicit spatiotemporal regularities contributes as well. To examine this possibility, we administered a novel virtual navigation task in which participants were required to walk through a winding corridor and then choose one of five marked doors to exit. Unknown to participants, the markings on the correct door reflected the corridor’s shape (from a bird’s eye view). Detecting this regularity negates the need to find the exit by trial and error. Participants performed the task twice a day for a week, while their overnight sleep was monitored. We found that the more time participants spent in SWS across the week, the better they were able to implicitly extract the hidden regularity. In contrast, the few participants that explicitly realized the regularity did not rely on SWS to do so. Moreover, the SWS effect was strictly at the trait-level: Baseline levels of SWS prior to the experimental week could predict success just as well, but day-to-day variations in SWS did not predict day-to-day improvements. We propose that our findings indicate SWS facilitates implicit integration of new information into cognitive maps, possibly through compressed memory replay.

Age affects reinforcement learning through dopamine-based learning imbalance and high decision noise-not through Parkinsonian mechanisms

Probabilistic reinforcement learning declines in healthy cognitive aging. While some findings suggest impairments are especially conspicuous in learning from rewards, resembling deficits in Parkinson's disease, others also show impairments in learning from punishments. To reconcile these findings, we tested 252 adults from 3 age groups on a probabilistic reinforcement learning task, analyzed trial-by-trial performance with a Q-reinforcement learning model, and correlated both fitted model parameters and behavior to polymorphisms in dopamine-related genes. Analyses revealed that learning from both positive and negative feedback declines with age but through different mechanisms: when learning from negative feedback, older adults were slower due to noisy decision-making; when learning from positive feedback, they tended to settle for a nonoptimal solution due to an imbalance in learning from positive and negative prediction errors. The imbalance was associated with polymorphisms in the DARPP-32 gene and appeared to arise from mechanisms different from those previously attributed to Parkinson's disease. Moreover, this imbalance predicted previous findings on aging using the Probabilistic Selection Task, which were misattributed to Parkinsonian mechanisms.

What can we learn from learning models about sensitivity to letter-order in visual word recognition?

Recent research on the effects of letter transposition in Indo-European Languages has shown that readers are surprisingly tolerant of these manipulations in a range of tasks. This evidence has motivated the development of new computational models of reading that regard flexibility in positional coding to be a core and universal principle of the reading process. Here we argue that such approach does not capture cross-linguistic differences in transposed-letter effects, nor do they explain them. To address this issue, we investigated how a simple domain-general connectionist architecture performs in tasks such as letter-transposition and letter substitution when it had learned to process words in the context of different linguistic environments. The results show that in spite of of the neurobiological noise involved in registering letter-position in all languages, flexibility and inflexibility in coding letter order is also shaped by the statistical orthographic properties of words in a language, such as the relative prevalence of anagrams. Our learning model also generated novel predictions for targeted empirical research, demonstrating a clear advantage of learning models for studying visual word recognition.

Integrating the automatic and the controlled: strategies in semantic priming in an attractor network with latching dynamics

Semantic priming has long been recognized to reflect, along with automatic semantic mechanisms, the contribution of controlled strategies. However, previous theories of controlled priming were mostly qualitative, lacking common grounds with modern mathematical models of automatic priming based on neural networks. Recently, we introduced a novel attractor network model of automatic semantic priming with latching dynamics. Here, we extend this work to show how the same model can also account for important findings regarding controlled processes. Assuming the rate of semantic transitions in the network can be adapted using simple reinforcement learning, we show how basic findings attributed to controlled processes in priming can be achieved, including their dependency on stimulus onset asynchrony and relatedness proportion and their unique effect on associative, category-exemplar, mediated and backward prime-target relations. We discuss how our mechanism relates to the classic expectancy theory and how it can be further extended in future developments of the model.

Internally- and externally-driven network transitions as a basis for automatic and strategic processes in semantic priming: theory and experimental validation

For the last four decades, semantic priming—the facilitation in recognition of a target word when it follows the presentation of a semantically related prime word—has been a central topic in research of human cognitive processing. Studies have drawn a complex picture of findings which demonstrated the sensitivity of this priming effect to a unique combination of variables, including, but not limited to, the type of relatedness between primes and targets, the prime-target Stimulus Onset Asynchrony (SOA), the relatedness proportion (RP) in the stimuli list and the specific task subjects are required to perform. Automatic processes depending on the activation patterns of semantic representations in memory and controlled strategies adapted by individuals when attempting to maximize their recognition performance have both been implicated in contributing to the results. Lately, we have published a new model of semantic priming that addresses the majority of these findings within one conceptual framework. In our model, semantic memory is depicted as an attractor neural network in which stochastic transitions from one stored pattern to another are continually taking place due to synaptic depression mechanisms. We have shown how such transitions, in combination with a reinforcement-learning rule that adjusts their pace, resemble the classic automatic and controlled processes involved in semantic priming and account for a great number of the findings in the literature. Here, we review the core findings of our model and present new simulations that show how similar principles of parameter-adjustments could account for additional data not addressed in our previous studies, such as the relation between expectancy and inhibition in priming, target frequency and target degradation effects. Finally, we describe two human experiments that validate several key predictions of the model.

Spreading activation in an attractor network with latching dynamics: automatic semantic priming revisited

Localist models of spreading activation (SA) and models assuming distributed representations offer very different takes on semantic priming, a widely investigated paradigm in word recognition and semantic memory research. In this study, we implemented SA in an attractor neural network model with distributed representations and created a unified framework for the two approaches. Our models assume a synaptic depression mechanism leading to autonomous transitions between encoded memory patterns (latching dynamics), which account for the major characteristics of automatic semantic priming in humans. Using computer simulations, we demonstrated how findings that challenged attractor-based networks in the past, such as mediated and asymmetric priming, are a natural consequence of our present model's dynamics. Puzzling results regarding backward priming were also given a straightforward explanation. In addition, the current model addresses some of the differences between semantic and associative relatedness and explains how these differences interact with stimulus onset asynchrony in priming experiments.

Excessive attractor instability accounts for semantic priming in schizophrenia

One of the most pervasive findings in studies of schizophrenics with thought disorders is their peculiar pattern of semantic priming, which presumably reflects abnormal associative processes in the semantic system of these patients. Semantic priming is manifested by faster and more accurate recognition of a word-target when preceded by a semantically related prime, relative to an unrelated prime condition. Compared to control, semantic priming in schizophrenics is characterized by reduced priming effects at long prime-target Stimulus Onset Asynchrony (SOA) and, sometimes, augmented priming at short SOA. In addition, unlike controls, schizophrenics consistently show indirect (mediated) priming (such as from the prime ‘wedding’ to the target ‘finger’, mediated by ‘ring’). In a previous study, we developed a novel attractor neural network model with synaptic adaptation mechanisms that could account for semantic priming patterns in healthy individuals. Here, we examine the consequences of introducing attractor instability to this network, which is hypothesized to arise from dysfunctional synaptic transmission known to occur in schizophrenia. In two simulated experiments, we demonstrate how such instability speeds up the network’s dynamics and, consequently, produces the full spectrum of priming effects previously reported in patients. The model also explains the inconsistency of augmented priming results at short SOAs using directly related pairs relative to the consistency of indirect priming. Further, we discuss how the same mechanism could account for other symptoms of the disease, such as derailment (‘loose associations’) or the commonly seen difficulty of patients in utilizing context. Finally, we show how the model can statistically implement the overly-broad wave of spreading activation previously presumed to characterize thought-disorders in schizophrenia.

Anal dilatation versus left lateral sphincterotomy for chronic anal fissure: a prospective randomized study

BACKGROUND: Several surgical methods are accepted for the treatment of chronic anal fissure. The most popular are anal dilatation (AD) and left lateral sphincterotomy (LLS). The objective of the current study was to prospectively evaluate the results of these two procedures in terms of recurrence rate, complications and patient satisfaction. METHODS: The study enrolled all patients who required operation for chronic anal fissure in the Division of General Surgery, Campus Golda, Rabin Medical Center, between the years 1997 and 2001. Exclusion criteria were acute anal fissure or inflammatory bowel disease. RESULTS: A total of 108 patients participated in the study, at an average age of 42.4 years (SD=12.5). The patients were randomly assigned to two groups; one for LLS (53 patients, 49.1%) and one for AD (55 patients, 50.9%). The study protocol included a questionnaire and a physical examination performed 1, 2, 3, 6 and 12 months after operation. The questionnaire contained questions about pain, bloody stool, incontinence for gas, fluid or hard feces, during the day or night, and soiling. The patients were also asked about their satisfaction on an analog scale from 1 to 10. The average follow-up was 11.2 months (SD=4.1). Minor incontinence occurred in 8 patients of AD group and in 2 patients of LLS group (p<0.005). Recurrence occurred in 6 cases of the AD group and in one case of the LLS group (p<0.003). Satisfaction score was insignificantly higher in the LLS group (9.1+/-0.8 in the LLS group and 7.4+/-2.0 in the AD group). CONCLUSIONS: These results suggest that LLS is the preferred method for the treatment for chronic anal fissure.

Rappaport-Vassiliadis medium for recovery of Salmonella spp. from low microbial load foods: collaborative study

Twenty-three laboratories participated in a collaborative study to compare the relative effectiveness of Rappaport-Vassiliadis (RV) medium incubated at 42 degrees C, selenite cystine (SC) broth (35 degrees C), and tetrathionate (TT) broth (35 and 43 degrees C) for recovery of Salmonella from the following foods with a low microbial load: dried egg yolk, dry active yeast, ground black pepper, guar gum, and instant nonfat dry milk. For dry active yeast, lauryl tryptose (LT) broth, incubated at 35 degrees C, was used instead of SC broth. All of the foods were artificially inoculated with single Salmonella serovars, that had been lyophilized before inoculation, at high and low target levels of 0.4 and 0.04 colony forming units/g food, respectively. For analysis of 870 test portions, representing all of the foods except yeast, 249 Salmonella-positive test portions were detected by RV medium, 265 by TT broth (43 degrees C), 268 by TT broth (35 degrees C), and 269 by SC broth (35 degrees C). For analysis of 225 test portions of yeast, 79 Salmonella-positive test portions were detected by RV medium, 79 by TT broth (43 degrees C), 84 by TT broth (35 degrees C), and 68 by LT broth (35 degrees C). RV medium was comparable to, or even more effective than, the other selective enrichments for recovery of Salmonella from all of the foods except guar gum. It is recommended that RV (42 degrees C) and TT (35 degrees C) be used with foods that have a low microbial load, except for guar gum for which SC (35 degrees C) and TT (35 degrees C) are recommended.

MAG3-F0 scintigraphy in decision making for emergency intervention in renal colic after helical CT positive for a urolith

Patients with renal colic are evaluated with clinical, laboratory, and imaging methods for stratification for emergency decompression, medical treatment, or discharge and follow up. The current standard practice is heavily based on unenhanced helical CT for detecting uroliths. However, the presence of a urolith does not necessarily mean that the kidney is obstructed and requires emergency decompression. In this study, technetium-mercaptoacetyltriglycine (MAG3) diuretic scintirenography was used to detect obstruction in patients with renal colic. The contribution of this test to patient management after positive findings from helical CT was also studied.

METHODS

Diagnostic criteria were established on the basis of previous experience with 60 patients who had renal colic and had undergone radiography of the kidneys, ureters, and urinary bladder (KUB) and diuretic Tc-MAG3 scintirenography and were followed up to correlate scintigraphic findings with clinical outcome. Subsequently, 80 patients with renal colic underwent scintigraphy within 12 h of presentation in the emergency room, after abdominal helical CT showed findings positive for calculus and suggestive of obstruction. After therapeutic oral or intravenous hydration and analgesics, diuretic dynamic renal scintigraphy (flow, function, delayed imaging) was performed after intravenous injections of 10 mCi (370 MBq) 99mTc-MAG3 and 40 mg furosemide (at zero time, or F0). Results were available soon after completion of the study and were considered in patient management. Four characteristic patterns of scintirenography, essential in patient stratification and treatment, had been standardized and were used for interpretation of the studies: the unobstructed kidney; the partially obstructed kidney, proximally or distally obstructed, with mild to severe obstruction and impairment of function; the totally obstructed kidney, with arrested renal function; and the unobstructed but dysfunctioning kidney after decompression, or stunned kidney.

RESULTS

Among the 80 patients with positive helical CT findings, 56.5% were found to have obstruction by scintigraphy (32.5% partially, 24% completely); the remaining 43.5% did not have obstruction (21% without an indication of recent obstruction and 22.5% with stunned kidneys after spontaneous decompression). Occasionally, findings of preexistent urine extravasation or infection were present. Patients who, by scintigraphy, never had obstruction or had experienced spontaneous decompression did not require admission or emergency intervention; those with complete or severe obstruction required admission and decompression for relief of pain or restoration of function, whereas those with mild obstruction were treated variably with forced fluids, analgesics, or, less frequently, elective surgery. Outcome information from clinical examination, imaging, and interventional findings indicated that this stratification was successful. The test caused no side effects.

CONCLUSION

For renal colic, clinical selection, KUB radiography, and even positive helical CT findings were all found to have a low positive predictive value for obstruction (in this study, 35%, 32%, and 56% respectively). Anatomic studies, including helical CT, should be followed by diuretic MAG3-F0 scintirenography to diagnose and quantify or exclude obstruction, detect spontaneous decompression, and appropriately stratify patients for emergency intervention, observation and medical therapy, or further work-up and discharge with referral to the clinic.

Twenty-four-hour direct presumptive enumeration of Listeria monocytogenes in food and environmental samples using the ISO-GRID method with LM-137 agar

A new culture medium, LM-137 agar, was developed for use with the ISO-GRID hydrophobic grid membrane filter system for direct presumptive enumeration of Listeria monocytogenes in 24 h. The method was validated against three-replicate, three-dilution most probable number procedures based on enrichment methods specified by the U.S. Department of Agriculture, the Association of Official Analytical Chemists International and the U.S. Food and Drug Administration. The study encompassed meats, dairy products, egg, produce, seafood, and environmental samples. The ISO-GRID filter method produced significantly higher recovery of L. monocytogenes from fermented sausage, hot dogs, pasteurized and raw milk, raw shrimp, and environmental swab samples (P < 0.05). The reference methods yielded significantly higher counts from frozen raw pork and cole slaw (P < 0.05). Confirmation rates of presumptive positive isolates from the filter method ranged from a low of 92% (frozen raw pork) to 100% (most other products). Neither the recovery efficiency nor the confirmation rate were affected by the presence of competing aerobic flora.

Enumeration of beta-glucuronidase-positive Escherichia coli in foods by using the ISO-GRID method with SD-39 agar

A study was undertaken to compare beta-glucuronidase-positive Escherichia coli counts produced by the ISO-GRID hydrophobic grid membrane filter method using SD-39 agar (test method) with those produced by AOAC Official Method 990.11, an existing ISO-GRID method using lactose monensin glucuronate agar and buffered MUG agar (reference method). The methods were evaluated using 21 food products, with three independent lots of five replicate samples analyzed per product by both methods. The test and reference methods were statistically equivalent for 19 of the 21 products; frozen, raw ground lamb produced significantly higher counts using the reference method, whereas counts obtained from cottage cheese were significantly higher using the SD-39 agar-based method.

Two-Day Hydrophobic Grid Membrane Filter Method for Yeast and Mold Enumeration in Foods Using YM-11 Agar: Collaborative Study

Twenty laboratories participated in a collaborative study to validate a 2-day hydrophobic grid membrane filter method using YM-11 agar for enumeration of yeast and mold in foods. Six naturally contaminated food products were included in the study: garlic powder, raw ground beef, walnuts, flour/meal, orange juice, and yogurt. The test method produced significantly higher results than the 5-day pour plate reference method for orange juice and significantly lower, though numerically similar, results for walnuts and yogurt. Differences between the test and reference methods were not significant for garlic powder, raw ground beef, or flour/meal. Repeatability and reproducibility were similar for both the test and reference methods in all cases. The hydrophobic grid membrane filter method for enumeration of yeast and mold in foods has been adopted by AOAC INTERNATIONAL.

Decrease in canine corneal endothelial cell density and increase in corneal thickness as functions of age

Fifty-nine normal dogs, ranging in age from 6 weeks to 132 months were examined with contact specular microscopy to determine the relationship of age to corneal endothelial cell density, morphology, and corneal thickness. Canine corneal endothelial cells appear quite similar to those of other species studied, including man. The hexagonally shaped canine endothelial cells tend to enlarge with age, with the population in young animals averaging around 2500 cells/mm2 and the number of cells in older dogs being frequently below 2100 cells/mm2. A significant increase in corneal thickness was observed with age. Healthy canine corneal endothelial cells appear to maintain a functional monolayer by enlargement and migration and represent a reasonable model for future endothelial cell study.