SUMMARYThe Youden Index is often used as a summary measure of the receiver operating characteristic curve. It measures the effectiveness of a diagnostic marker and permits the selection of an optimal threshold value or cutoff point for the biomarker of interest. Some markers, while basically continuous and positive, have a spike or positive mass of probability at the value zero. We provide a flexible modeling approach for estimating the Youden Index and its associated cutoff point for such spiked data and compare it with the standard empirical approach. We show how this modeling approach can be adjusted to take covariate information into account. This approach is applied to data on the Coronary Calcium Score, a marker for atherosclerosis.

Neural stem cells (NSCs) in the dentate gyrus (DG) reside in a specialized local niche that supports their neurogenic proliferation to produce adult-born neurons throughout life. How local niche cells interact at the circuit level to ensure continuous neurogenesis from NSCs remains unknown. Here we report the role of endogenous neuropeptide cholecystokinin (CCK), released from dentate CCK interneurons, in regulating neurogenic niche cells and NSCs. Specifically, stimulating CCK release supports neurogenic proliferation of NSCs through a dominant astrocytemediated glutamatergic signaling cascade. In contrast, reducing dentate CCK induces reactive astrocytes, which correlates with decreased neurogenic proliferation of NSCs and upregulation of genes involved in immune processes. Our findings provide novel circuit-based information on how CCK acts on local astrocytes to regulate the key behavior of adult NSCs.

Posttraumatic stress disorder (PTSD) symptoms and pain after traumatic events such as motor vehicle collision (MVC) have been proposed to be mutually promoting. We performed a prospective multicenter study that enrolled 948 individuals who presented to the emergency department within 24 hours of MVC and were discharged home after evaluation. Follow-up evaluations were completed 6 weeks, 6 months, and 1 year after MVC. Path analysis results supported the hypothesis that axial pain after MVC consistently promotes the maintenance of hyperarousal and intrusive symptoms, from the early weeks after injury through 1 year. In addition, path analysis results supported the hypothesis that one or more PTSD symptom clusters had an influence on axial pain outcomes throughout the year after MVC, with hyperarousal symptoms most influencing axial pain persistence in the initial months after MVC. The influence of hyperarousal symptoms on pain persistence was only present among individuals with genetic vulnerability to stress-induced pain, suggesting specific mechanisms by which hyperarousal symptoms may lead to hyperalgesia and allodynia. Further studies are needed to better understand the specific mechanisms by which pain and PTSD symptoms enhance one another after trauma, and how such mechanisms vary among specific patient subgroups, to better inform the development of secondary preventive interventions.

Objectives-Patients with functional gastrointestinal (GI) disorders treated with tricyclic antidepressants may report non-GI symptoms. It is unclear whether these symptoms are side effects of the medication or reflect a general behavioral tendency to report symptoms. This study 1) evaluated whether a checklist of symptoms reported by patients prior to taking desipramine increased in number or worsened in severity after being on a tricyclic antidepressant (desipramine), and 2) assessed baseline factors that predispose patients to report symptoms.Methods-Female patients in the drug arm of a multi-center NIH treatment trial for functional bowel disorders completed a 15 item symptom questionnaire at baseline before randomization and at 2 weeks after starting Desipramine (n=81), or placebo (n=40) and at study completion 12 weeks later. Patients were asked on each occasion if they experienced any of 15 Symptoms and its level of severity and frequency, and the results were compared.Results-A total of 57 patients in the desipramine arm who completed the questionnaire at both week 0 and week 2 comprised the study sample. Certain symptoms reported as side effects: dizziness, dry mouth/thirstiness, lightheadedness, feeling jittery or tremors and flushing not only were reported more often but also worsened at week 2 indicating a drug effect. Conversely, other symptoms that were also reported as side effects: feeling tired in AM, nausea, blurred vision, headaches, decreased appetite, and trouble sleeping either did not change in severity or showed improvement at week 2 (tiredness). All these symptoms except trouble sleeping were reported less often at Week 2 than at baseline (Week 2). Psychological distress but not desipramine level significantly correlated with symptom reporting.Conclusions-The majority of symptoms often attributed to side effects of desipramine were present prior to treatment, and only a few related to its anticholinergic effects worsened 2 weeks after beginning treatment, suggesting that most symptoms considered as side effects were not related to drug per se. Clinicians should consider that "Side effects" may relate more to psychological distress than to drug effects.

Obesity has been found to increase the risk of musculoskeletal pain (MSP) in other settings, but to our knowledge, the influence of increased body mass index on pain outcomes after common trauma exposures such as motor vehicle collision (MVC) has not been assessed. In addition, obesity results in biomechanical changes, as well as physiologic changes including reduced hypothalamic pituitary adrenal axis negative feedback inhibition, but mechanisms by which obesity may result in worse post-traumatic outcomes remain poorly understood. In this study, we evaluated the influence of body mass index on axial and overall MSP severity (0-10 numeric rating scale) 6 weeks, 6 months, and 1 year after MVC among 917 European Americans who presented to the emergency department for initial evaluation. After adjusting for an array of sociodemographic factors, obesity (particularly morbid obesity) was an independent risk factor for worse MSP after MVC (eg, RR 1.41 [95% CI 1.11, 1.80] for moderate or severe MSP 6 months after MVC among morbidly obese vs normal weight MVC survivors). Interestingly, substantial effect modification was observed between obesity risk and a genetic variant known to reduce hypothalamic pituitary adrenal axis negative feedback inhibition (FKBP5 rs9380526). (eg, 41% vs 16% increased risk of moderate or severe MSP at 6 months among obese individuals with and without the risk allele.) Further studies are needed to elucidate mechanisms underlying chronic pain development in obese trauma survivors and to develop interventions that will reduce chronic pain severity among this common, at-risk group.