Radiocarbon constraints on the glacial ocean circulation and its impact on atmospheric CO2

While the ocean’s large-scale overturning circulation is thought to have been significantly different under the climatic conditions of the Last Glacial Maximum (LGM), the exact nature of the glacial circulation and its implications for global carbon cycling continue to be debated. Here we use a global array of ocean–atmosphere radiocarbon disequilibrium estimates to demonstrate a ∼689±53 14C-yr increase in the average residence time of carbon in the deep ocean at the LGM. A predominantly southern-sourced abyssal overturning limb that was more isolated from its shallower northern counterparts is interpreted to have extended from the Southern Ocean, producing a widespread radiocarbon age maximum at mid-depths and depriving the deep ocean of a fast escape route for accumulating respired carbon. While the exact magnitude of the resulting carbon cycle impacts remains to be confirmed, the radiocarbon data suggest an increase in the efficiency of the biological carbon pump that could have accounted for as much as half of the glacial–interglacial CO2 change

Metabolic alterations during the growth of tumour spheroids

Solid tumours undergo considerable alterations in their metabolism of nutrients in order to generate sufficient energy and biomass for sustained growth and proliferation. During growth, the tumour microenvironment exerts a number of influences (e.g. hypoxia and acidity) that affect cellular biology and the flux or utilisation of fuels including glucose. The tumour spheroid model was used to characterise the utilisation of glucose and describe alterations to the activity and expression of key glycolytic enzymes during the tissue growth curve. Glucose was avidly consumed and associated with the production of lactate and an acidified medium, confirming the reliance on glycolytic pathways and a diminution of oxidative phosphorylation. The expression levels and activities of hexokinase, phosphofructokinase-1, pyruvate kinase and lactate dehydrogenase in the glycolytic pathway were measured to assess glycolytic capacity. Similar measurements were made for glucose-6-phosphate dehydrogenase, the entry point and regulatory step of the pentose-phosphate pathway (PPP) and for cytosolic malate dehydrogenase, a key link to TCA cycle intermediates. The parameters for these key enzymes were shown to undergo considerable variation during the growth curve of tumour spheroids. In addition, they revealed that the dynamic alterations were influenced by both transcriptional and posttranslational mechanisms

Metabolic alterations during the growth of tumour spheroids

Solid tumours undergo considerable alterations in their metabolism of nutrients in order to generate sufficient energy and biomass for sustained growth and proliferation. During growth, the tumour microenvironment exerts a number of influences (e.g. hypoxia and acidity) that affect cellular biology and the flux or utilisation of fuels including glucose. The tumour spheroid model was used to characterise the utilisation of glucose and describe alterations to the activity and expression of key glycolytic enzymes during the tissue growth curve. Glucose was avidly consumed and associated with the production of lactate and an acidified medium, confirming the reliance on glycolytic pathways and a diminution of oxidative phosphorylation. The expression levels and activities of hexokinase, phosphofructokinase-1, pyruvate kinase and lactate dehydrogenase in the glycolytic pathway were measured to assess glycolytic capacity. Similar measurements were made for glucose-6-phosphate dehydrogenase, the entry point and regulatory step of the pentose-phosphate pathway (PPP) and for cytosolic malate dehydrogenase, a key link to TCA cycle intermediates. The parameters for these key enzymes were shown to undergo considerable variation during the growth curve of tumour spheroids. In addition, they revealed that the dynamic alterations were influenced by both transcriptional and posttranslational mechanisms

Thank You to Our 2023 Peer Reviewers

On behalf of the AGU Advances editorial team, we would like to express our sincere gratitude to everyone who reviewed manuscripts for us in 2023. Peer review is time-consuming, but it remains essential to the scientific process. Advances reviewers continue to help define the scope of our journal by commenting specifically on whether a paper is likely to have broad and immediate impact. We also appreciate the degree to which reviewers have embraced AGU's open data strategies, although this obviously takes more time

Sleep disruption due to nocturnal heartburn: a review of the evidence and clinical implications

Nocturnal heartburn (NHB) is a symptom that affects up to 25% of the general population and has been shown to cause sleep disruption that adversely affects quality of life and psychomotor performance. Few studies have evaluated the association between occasional NHB and sleep disturbances; therefore, this connection may be underappreciated and left untreated by the primary care provider and patient, with potentially significant negative clinical consequences and effects on quality of life. This review sought to describe what is currently known about the interplay between occasional NHB and sleep disruption, and identify whether acid suppression therapy can improve symptoms of occasional NHB and associated sleep disruptions. The pathophysiology of heartburn-induced sleep disruption appears to follow a bidirectional cycle due to the normal physiologic changes that occur in the upper gastrointestinal tract during sleep and due to the potential for heartburn symptoms to cause sleep arousal. The majority of the identified studies suggested that pharmacologic interventions for acid reduction, including proton pump inhibitors or histamine type-2 receptor antagonists (H2RAs), improved objective and/or subjective sleep outcomes among individuals with gastroesophageal reflux disease (GERD) and NHB. Several studies specific to famotidine demonstrated that treatment with 10 mg or 20 mg reduced nighttime awakenings due to NHB. In conclusion, NHB symptoms can cause sleep dysfunction that can have a profound adverse downstream effect on quality of life, next-day functioning, and health-related outcomes. The current approach to managing occasional NHB is similar to that associated with GERD, highlighting the need for studies specific to the occasional heartburn population. Health care providers should investigate NHB as one of the potential causes of sleep complaints, and patients with heartburn should be questioned about sleep quality, recalled arousals, next-day vitality, early fatigue, and next-day functioning