Assays of glucose tolerance factor and its mode of action, studied with brewer's yeast

Glucose tolerance factor (GTF) has usually been assayed by manometric measurement of CO2 evolved when glucose was metabolizing glucose. By using 14C labeled substrates it has been shown that GTF increases the decarboxylation of pyruvate to ethanol and CO2. Thus in addition to measuring CO2 evolution, the enzymatic estimation of the increased ethanol production can be used to assay GTF. A further effect of GTF was to cause increased carboxylation of pyruvate to substrates that are used in the biosynthesis of cell substance. The metabolic sites of action of GTF are discussed.

Sleep loss disrupts the neural signature of successful learning

Sleep supports memory consolidation as well as next-day learning. The influential "Active Systems" account of offline consolidation suggests that sleep-associated memory processing paves the way for new learning, but empirical evidence in support of this idea is scarce. Using a within-subjects (n = 30), crossover design, we assessed behavioral and electrophysiological indices of episodic encoding after a night of sleep or total sleep deprivation in healthy adults (aged 18-25 years) and investigated whether behavioral performance was predicted by the overnight consolidation of episodic associations from the previous day. Sleep supported memory consolidation and next-day learning as compared to sleep deprivation. However, the magnitude of this sleep-associated consolidation benefit did not significantly predict the ability to form novel memories after sleep. Interestingly, sleep deprivation prompted a qualitative change in the neural signature of encoding: Whereas 12-20 Hz beta desynchronization-an established marker of successful encoding-was observed after sleep, sleep deprivation disrupted beta desynchrony during successful learning. Taken together, these findings suggest that effective learning depends on sleep but not necessarily on sleep-associated consolidation.

Primary solid neoplasms of the greater omentum

Primary solid tumors of the greater omentum are rare, with only 42 reported cases. Malignant hemangiopericytomas constitute only three of these cases. The 40-year-old patient described in this report had abdominal pain, a palpable abdominal mass, early satiety, and weight loss. At laparotomy a large omental hemangiopericytoma was excised, and no other evidence of disease was grossly evident. Eighteen months after initial laparotomy, the patient had widespread progression of the tumor and, despite chemotherapy, died 2 months later. A review of reported cases shows that abdominal discomfort (56%) and mass (35%) are the most common clinical characteristics of a primary omental tumor. Weight loss, ascites, and peritoneal implants usually indicate malignancy. Rare long-term follow-up prevents definitive conclusions regarding therapy and prognosis. At present, surgical excision alone appears to be the treatment of choice, with no demonstrable benefit from either chemotherapy or radiation.

Successful Virtual CPAP Set up in Obstructive Sleep Apnoea: A positive innovation during the pandemic

BACKGROUND

Traditionally continuous positive airways pressure (CPAP) trials for obstructive sleep apnoea (OSA) are through face to face (F2F) set up. During Covid-19 pandemic CPAP was classed as aerosol-generating hence Leeds sleep service moved to a virtual service. Patients received equipment by post followed by virtual reviews (VR). We evaluated the adherence and symptomatic benefit of postal compared to F2F method.

METHODS

Observational data were collected from databases monitoring CPAP loans. F2F patients met a sleep technician for hands on setup in 2019, and in 2020 postal patients received equipment, written guides, and links to custom made YouTube videos. All (F2F and postal) patients had a telephone and VR appointment to discuss symptoms, and CPAP machine (AirSense 10, ResMed Inc., San Diego, USA) data including data on usage and treatment apnoea-hypopnoea index (AHI). Data was analysed using unpaired T-tests, Mann-Whitney U tests, and chi-square tests to examine differences in means, medians, and proportions, respectively of the F2F and postal groups.

RESULTS

Both groups (n = 1,221, 656 F2F, 53.7%) were similar in all categories except length of CPAP trial (postal 33 vs F2F 84 days,p < 0.0001), change in AHI (postal 22.4/Hr vs F2F 25.1/Hr,p = 0.04), and trial average use (postal 4.9 vs F2F 5.2 h,p = 0.04). There was no significant difference in the proportion of patients continuing with CPAP (postal 64%, F2F 66%, p = 0.71), the improvement in Epworth Sleepiness Score (ESS) (postal 6.9/24, F2F 7.1/24, p = 0.31) or the patient's subjective rating on whether they felt much better, better, the same or worse on CPAP (p = 0.27). Logistic regression showed factors which affected odds ratios of continuing CPAP were diagnostic AHI, treatment AHI, treatment ESS and how they felt on CPAP. Trial type did not affect the odds ratios of continuing CPAP.

CONCLUSIONS

Postal CPAP trial patients had similar odds of continuing CPAP therapy compared to patients with F2F trials and achieved similar levels of ESS improvement and reporting feeling better on CPAP. This provides support for postal trials as a viable option post-pandemic.

0102 The Relationship Between Overnight Consolidation and Next-Day Learning

Introduction

Contemporary models of sleep-associated consolidation posit that overnight memory processing paves the way for next-day learning in hippocampus. However, the extent to which new hippocampal learning is dependent on overnight consolidation has yet to be investigated. In this study, we compared the impacts of sleep and sleep deprivation on the consolidation and encoding of hippocampus-dependent memories and, importantly, examined whether individual differences in consolidation were associated with individual differences in encoding.

Methods

Thirty healthy adults (17 females, mean age 20.1±1.65) were trained on a spatial memory task in the evening before a night of sleep or total sleep deprivation (repeated measures). Participants completed a spatial memory test the following morning, and then encoded a novel set of word-image pairs. Two days later (after recovery sleep), memory for the word-image pairs was tested. We predicted that participants’ spatial memory recall would predict performance on the word-image test, suggesting that overnight consolidation lays the groundwork for new encoding in hippocampus.

Results

Sleep (vs. sleep deprivation) improved spatial memory accuracy the following morning (t(29)=3.93, p&lt;.001, d=0.72) and word-image recall two days later (t(29)=12.19, p&lt;.001, d=2.23), suggesting that sleep facilitated the consolidation and encoding of hippocampus-dependent memories, respectively. However, the benefit of sleep for spatial memory recall was not significantly correlated with the benefit of sleep for word-image encoding (r(28)= 0.01, p=0.971), suggesting that hippocampal encoding was not contingent on foregoing overnight consolidation processes.

Conclusion

In support of previous findings, overnight sleep improved consolidation and next-day encoding, as compared to an equivalent period of sleep deprivation. However, the present results did not reveal any relationship between an individual’s sleep-associated consolidation and their next-day learning.

Support

Department of Psychology, University of York scholarship to A.áV.G. Medical Research Council Career Development Award (MR/P020208/1) to S.A.C.