Clinical signs associated with severe ST segment elevation in three cats with a hypertrophic cardiomyopathy phenotype.

Three cats were presented for unusual collapsing episodes. Echocardiography revealed a hypertrophic cardiomyopathy (HCM) phenotype in each cat. Continuous electrocardiographic monitoring showed that the clinical signs coincided with periods of severe ST-segment elevation in each cat. The first cat was treated with amlodipine and diltiazem but did not improve and was euthanized due to poor quality of life. Postmortem examination revealed cardiac lymphoma without obstructive coronary disease. The second cat was thought to have cardiac lymphoma, based on pericardial effusion cytology, and was euthanized before starting therapy. The third cat was diagnosed with HCM and left ventricular outflow tract obstruction and was treated with atenolol and diltiazem. This treatment reduced the frequency of episodic clinical signs, but the cat subsequently developed congestive heart failure and was euthanized. This case series describes clinical signs associated with severe ST elevation in cats with an HCM phenotype, and their outcomes. Continuous electrocardiographic monitoring was necessary to detect transient ST elevation in each case.

Neutron spectroscopy of plutonium using a handheld detection system.

The ability to distinguish multiple forms of plutonium from one another, such as oxide and metal, is paramount in areas of nuclear nonproliferation and international safeguards. In its metal form, plutonium can be readily used in a nuclear weapon, while oxide forms are associated with nuclear reactor fuel. Oxide-based plutonium forms emit neutrons with an energy spectrum that is significantly different from the fission neutrons that are emitted from plutonium metal. Organic scintillation detectors output pulses that are proportional to the neutron energy deposited, and therefore present a means of distinguishing these plutonium forms based on their energy spectra. In this work, metal and oxide forms of plutonium were measured using a handheld detection system based on an organic glass scintillator. Monte Carlo modeling of these experiments was performed to provide insight into the origin of the features in the observed light output spectra. Through analysis of multiple regions of these spectra, in a matter of minutes we were able to unambiguously discriminate oxide and metal plutonium forms from one another and from a plutonium-beryllium neutron source, which was considered for comparison because these sources are commonly used in industrial applications. The ability to discriminate weapons-usable material from nuclear reactor fuel has applications in nuclear treaty verification and safeguards.

Impact of non-invasive post-mortem micro-CT imaging on a fetal autopsy service: a single centre retrospective study.

AIM: To evaluate the impact of a new, less-invasive micro-computed tomography (CT) service on autopsy service provision. We recorded parental consent, type of autopsy performed, autopsy reporting times and time taken for the body to be released from the mortuary. MATERIALS AND METHODS: A retrospective, single-centre case series was conducted for all perinatal deaths since the introduction of our micro-CT service in 2016, with a detailed review of records extracted from 2019 and 2021. Fetal demographics (gestational age, weight), type of autopsy conducted, and the time taken from receiving the body to releasing the body and issuing a final report were recorded. RESULTS: Micro-CT imaging uptake increased to over two hundred cases/year by 2021. Overall, invasive autopsies reduced from (45.8%, 196/428; 2019) to (32.1%, 125/390; 2021) with an equivalent rise in less-invasive autopsy from 54.2% (232/428;2019) to 67.9% (265/390;2019). Offering a micro-CT service resulted in an increase in consent to imaging-based autopsies from (76.9%, 329/428;2019) to (87.2%, 340/390;2021). Micro-CT has become the most common post-mortem imaging performed in our institution at 54.4% (212/251;2021), although the body preparation time from the tissue staining required has increased the time to provide an autopsy report to 17 days and release of the body to 18 days. CONCLUSION: Our study shows that introducing a micro-CT post-mortem imaging service was associated with reduced use of conventional invasive procedures, despite a slight increase in turnaround times. Understanding these factors and continued improvements in micro-CT service delivery will help make this accessible to a wider population in the future.

Temporal asymmetry of neural representations predicts memory decisions.

A stimulus can be familiar for multiple reasons. It might have been recently encountered, or is similar to recent experience, or is similar to 'typical' experience. Understanding how the brain translates these sources of similarity into memory decisions is a fundamental, but challenging goal. Here, using fMRI, we computed neural similarity between a current stimulus and events from different temporal windows in the past and future (from seconds to days). We show that trial-by-trial memory decisions (is this stimulus 'old'?) were predicted by the difference in similarity to past vs. future events (temporal asymmetry). This relationship was (i) evident in lateral parietal and occipitotemporal cortices, (ii) strongest when considering events from the recent past (minutes ago), and (iii) most pronounced when veridical (true) memories were weak. These findings suggest a new perspective in which the brain supports memory decisions by comparing what actually occurred to what is likely to occur.

Clinical characteristics of women with HIV in the RESPOND cohort: A descriptive analysis and comparison to men.

BACKGROUND: Women with HIV are globally underrepresented in clinical research. Existing studies often focus on reproductive outcomes, seldom focus on older women, and are often underpowered to assess sex/gender differences. We describe CD4, HIV viral load (VL), clinical characteristics, comorbidity burden, and use of antiretroviral therapy (ART) among women with HIV in the RESPOND study and compare them with those of the men in RESPOND. METHODS: RESPOND is a prospective, multi-cohort collaboration including over 34 000 people with HIV from across Europe and Australia. Demographic and clinical characteristics, including CD4/VL, comorbidity burden, and ART are presented at baseline, defined as the latter of 1 January 2012 or enrolment into the local cohort, stratified by age and sex/gender. We further stratify men by reported mode of HIV acquisition, men who have sex with men (MSM) and non-MSM. RESULTS: Women account for 26.0% (n = 9019) of the cohort, with a median age of 42.2 years (interquartile range [IQR] 34.7-49.1). The majority (59.3%) of women were white, followed by 30.3% Black. Most women (75.8%) had acquired HIV heterosexually and 15.9% via injecting drug use. Nearly half (44.8%) were receiving a boosted protease inhibitor, 31.4% a non-nucleoside reverse transcriptase inhibitor, and 7.8% an integrase strand transfer inhibitor. The baseline year was 2012 for 73.2% of women and >2019 for 4.2%. Median CD4 was 523 (IQR 350-722) cells/µl, and 73.6% of women had a VL <200 copies/mL. Among the ART-naïve population, women were more likely than MSM but less likely than non-MSM (p < 0.001) to have CD4 <200 cells/µL and less likely than both MSM and non-MSM (p < 0.001) to have VL ≥100 000 copies/mL. Women were also more likely to be free of comorbidity than were both MSM and non-MSM (p < 0.0001). CONCLUSION: RESPOND women are diverse in age, ethnicity/race, CD4/VL, and comorbidity burden, with important differences relative to men. This work highlights the importance of stratification by sex/gender for future research that may help improve screening and management guidelines specifically for women with HIV.

Recall as a Window into Hippocampally Defined Events.

We experience the present as a continuous stream of information, but often experience the past in parcels of unique events or episodes. Decades of research have helped to articulate how we perform this event segmentation in the moment, as well as how events and their boundaries influence what we later remember. More recently, neuroscientific research has suggested that the hippocampus plays a role at critical moments during event formation alongside its established role in enabling subsequent recall. Here, we review and explore the relationship between event processing and recall with the perspective that it can be uniquely characterized by the contributions of the hippocampus and its interactions with the rest of the brain. Specifically, we highlight a growing number of empirical studies suggesting that the hippocampus is important for processing events that have just ended, bridging the gap between the prior and current event, and influencing the contents and trajectories of recalled information. We also catalogue and summarize the multifaceted sets of findings concerning how recall is influenced by event structure. Lastly, we discuss several exciting directions for future research and how our understanding of events might be enriched by characterizing them in terms of the operations of different regions of the brain.

Benefits of spaced learning are predicted by re-encoding of past experience in ventromedial prefrontal cortex.

More than a century of research shows that spaced learning improves long-term memory. Yet, there remains debate concerning why. A major limitation to resolving theoretical debates is the lack of evidence for how neural representations change as a function of spacing. Here, leveraging a massive-scale 7T human fMRI dataset, we tracked neural representations and behavioral expressions of memory as participants viewed thousands of natural scene images that repeated at lags ranging from seconds to many months. We show that spaced learning increases the similarity of human ventromedial prefrontal cortex representations across stimulus encounters and, critically, these increases parallel and predict the behavioral benefits of spacing. Additionally, we show that these spacing benefits critically depend on remembering and, in turn, 're-encoding' past experience. Collectively, our findings provide fundamental insight into how spaced learning influences neural representations and why spacing is beneficial.