A Clinical Prediction Model to Assess Risk for Pancreatic Cancer Among Patients With Acute Pancreatitis.

OBJECTIVES: We aimed to develop and validate a prediction model as the first step in a sequential screening strategy to identify acute pancreatitis (AP) individuals at risk for pancreatic cancer (PC). MATERIALS AND METHODS: We performed a population-based retrospective cohort study among individuals 40 years or older with a hospitalization for AP in the US Veterans Health Administration. For variable selection, we used least absolute shrinkage and selection operator regression with 10-fold cross-validation to identify a parsimonious logistic regression model for predicting the outcome, PC diagnosed within 2 years after AP. We evaluated model discrimination and calibration. RESULTS: Among 51,613 eligible study patients with AP, 801 individuals were diagnosed with PC within 2 years. The final model (area under the receiver operating curve, 0.70; 95% confidence interval, 0.67-0.73) included histories of gallstones, pancreatic cyst, alcohol use, smoking, and levels of bilirubin, triglycerides, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, and albumin. If the predicted risk threshold was set at 2% over 2 years, 20.3% of the AP population would undergo definitive screening, identifying nearly 50% of PC associated with AP. CONCLUSIONS: We developed a prediction model using widely available clinical factors to identify high-risk patients with PC-associated AP, the first step in a sequential screening strategy.

The ultimate tradeoff: how red cell adaptations to malaria alter the host response during critical illness.

The human immune system evolved in response to pathogens. Among these pathogens, malaria has proven to be one of the deadliest and has exerted the most potent selective pressures on its target cell, the red blood cell. Red blood cells have recently gained recognition for their immunomodulatory properties, yet how red cell adaptations contribute to the host response during critical illness remains understudied. This review will discuss how adaptations that may have been advantageous for host survival might influence immune responses in modern critical illness. We will highlight the current evidence for divergent host resilience arising from the adaptations to malaria and summarize how understanding evolutionary red cell adaptations to malaria may provide insight into the heterogeneity of the host response to critical illness, perhaps driving future precision medicine approaches to syndromes affecting the critically ill such as sepsis and acute respiratory distress syndrome (ARDS).

Development and validation of case-finding algorithms to identify acute pancreatitis in the Veterans Health Administration.

PURPOSE: Acute pancreatitis (AP) is a frequently encountered adverse drug reaction. However, the validity of diagnostic codes for AP is unknown. We aimed to determine the positive predictive value (PPV) of a diagnostic code-based algorithm for identifying patients with AP within the US Veterans Health Administration and evaluate the value of adding readily available structured laboratory information. METHODS: We identified patients with possible AP events first based on the presence of a single hospital discharge ICD-9 or ICD-10 diagnosis of AP (Algorithm 1). We then expanded Algorithm 1 by including relevant laboratory test results (Algorithm 2). Specifically, we considered amylase or lipase serum values obtained between 2 days before admission and the end of the hospitalization. Medical records of a random sample of patients identified by the respective algorithms were reviewed by two separate gastroenterologists to adjudicate AP events. The PPV (95% confidence interval [CI]) for the algorithms were calculated. RESULTS: Algorithm 2, consisting of one ICD-9 or ICD-10 hospital discharge diagnosis of AP and the addition of lipase serum value ≥200 U/L, had a PPV 89.1% (95% CI 83.0%-95.2%), improving from the PPV of algorithm 1 (57.9% [95% CI 46.8-69.0]). CONCLUSIONS: An algorithm consisting of an ICD-9 or ICD-10 diagnosis of AP with a lipase value ≥200 U/L achieved high PPV. This simple algorithm can be readily implemented in any electronic health records (EHR) systems and could be useful for future pharmacoepidemiologic studies on AP.

Immunomodulatory roles of red blood cells.

PURPOSE OF THE REVIEW: To discuss recent advances supporting the role of red blood cells (RBCs) in the host immune response. RECENT FINDINGS: Over the last century, research has demonstrated that red blood cells exhibit functions beyond oxygen transport, including immune function. Recent work indicates that the nucleic acid sensing receptor, toll-like receptor 9 (TLR9), is expressed on the RBC surface and implicated in innate immune activation and red cell clearance during inflammatory states. In addition to this DNA-sensing role of RBCs, there is growing evidence that RBCs may influence immune function by inducing vascular dysfunction. RBC proteomics and metabolomics have provided additional insight into RBC immune function, with several studies indicating changes to RBC membrane structure and metabolism in response to severe acute respiratory syndrome coronavirus 2 infection. These structural RBC changes may even provide insight into the pathophysiology of the 'long-coronavirus disease 2019' phenomenon. Finally, evidence suggests that RBCs may influence host immune responses via complement regulation. Taken together, these recent findings indicate RBCs possess immune function. Further studies will be required to elucidate better how RBC immune function contributes to the heterogeneous host response during inflammatory states. SUMMARY: The appreciation for nongas exchanging, red blood cell immune functions is rapidly growing. A better understanding of these RBC functions may provide insight into the heterogeneity observed in the host immune response to infection and inflammation.

Bat Red Blood Cells Express Nucleic Acid-Sensing Receptors and Bind RNA and DNA.

RBCs demonstrate immunomodulatory capabilities through the expression of nucleic acid sensors. However, little is known about bat RBCs, and no studies have examined the immune function of bat erythrocytes. In this study, we show that bat RBCs express the nucleic acid-sensing TLRs TLR7 and TLR9 and bind the nucleic acid ligands, ssRNA, and CpG DNA. Collectively, these data suggest that, like human RBCs, bat erythrocytes possess immune function and may be reservoirs for nucleic acids. These findings provide unique insight into bat immunity and may uncover potential mechanisms by which virulent pathogens of humans are concealed in bats.

Anemia in a young Guinean male.

The etiology of anemia in adults is often multifactorial. This case highlights an uncommon combination of causes of anemia and the importance of a diagnostic workup guided by a patient's unique history, risk factors, and laboratory findings.

Passive Coping Strategies During Repeated Social Defeat Are Associated With Long-Lasting Changes in Sleep in Rats.

Exposure to severe stress has immediate and prolonged neuropsychiatric consequences and increases the risk of developing Posttraumatic Stress Disorder (PTSD). Importantly, PTSD develops in only a subset of individuals after exposure to a traumatic event, with the understanding of this selective vulnerability being very limited. Individuals who go on to develop PTSD after a traumatic experience typically demonstrate sleep disturbances including persistent insomnia and recurrent trauma-related nightmares. We previously established a repeated social defeat paradigm in which rats segregate into either passively or actively coping subpopulations, and we found that this distinction correlates with measures of vulnerability or resilience to stress. In this study, we examined differences between these two behavioral phenotypes in sleep changes resulting from repeated social defeat stress. Our data indicate that, compared to control and actively coping rats, passively coping rats have less slow-wave sleep (SWS) for at least 2 weeks after the end of a series of exposures to social defeat. Furthermore, resilient rats show less exaggerated motor activation at awakenings from rapid eye movement (REM) sleep and less fragmentation of REM sleep compared to control and passively coping rats. Together, these data associate a passive coping strategy in response to repeated social defeat stress with persisting sleep disturbances. Conversely, an active coping strategy may be associated with resilience to sleep disturbances. These findings may have both prognostic and therapeutic applications to stress-associated neuropsychiatric disorders, including PTSD.

Orexin signaling during social defeat stress influences subsequent social interaction behaviour and recognition memory.

Orexins are neuropeptides synthesized in the lateral hypothalamus that influence arousal, feeding, reward pathways, and the response to stress. However, the role of orexins in repeated stress is not fully characterized. Here, we examined how orexins and their receptors contribute to the coping response during repeated social defeat and subsequent anxiety-like and memory-related behaviors. Specifically, we used Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) to stimulate orexins prior to each of five consecutive days of social defeat stress in adult male rats. Additionally, we determined the role of the orexin 2 receptor in these behaviors by using a selective orexin 2 receptor antagonist (MK-1064) administered prior to each social defeat. Following the 5 day social defeat conditioning period, rats were evaluated in social interaction and novel object recognition paradigms to assess anxiety-like behavior and recognition memory, respectively. Activation of orexin neurons by DREADDs prior to each social defeat decreased the average latency to become defeated across 5 days, indicative of a passive coping strategy that we have previously linked to a stress vulnerable phenotype. Moreover, stimulation of orexin signaling during defeat conditioning decreased subsequent social interaction and performance in the novel object recognition test indicating increased subsequent anxiety-like behavior and reduced recognition memory. Blocking the orexin 2 receptor during repeated defeat did not alter these effects. Together, our results suggest that orexin neuron activation produces a passive coping phenotype during social defeat leading to subsequent anxiety-like behaviors and memory deficits.

Reduced Orexin System Function Contributes to Resilience to Repeated Social Stress.

Exposure to stress increases the risk of developing affective disorders such as depression and post-traumatic stress disorder (PTSD). However, these disorders occur in only a subset of individuals, those that are more vulnerable to the effects of stress, whereas others remain resilient. The coping style adopted to deal with the stressor, either passive or active coping, is related to vulnerability or resilience, respectively. Important neural substrates that mediate responses to a stressor are the orexins. These neuropeptides are altered in the cerebrospinal fluid of patients with stress-related illnesses such as depression and PTSD. The present experiments used a rodent social defeat model that generates actively coping rats and passively coping rats, which we have previously shown exhibit resilient and vulnerable profiles, respectively, to examine if orexins play a role in these stress-induced phenotypes. In situ radiolabeling and qPCR revealed that actively coping rats expressed significantly lower prepro-orexin mRNA compared with passively coping rats. This led to the hypothesis that lower levels of orexins contribute to resilience to repeated social stress. To test this hypothesis, rats first underwent 5 d of social defeat to establish active and passive coping phenotypes. Then, orexin neurons were inhibited before each social defeat for three additional days using designer receptors exclusively activated by designer drugs (DREADDs). Inhibition of orexins increased social interaction behavior and decreased depressive-like behavior in the vulnerable population of rats. Indeed, these data suggest that lowering orexins promoted resilience to social defeat and may be an important target for treatment of stress-related disorders.