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Structural Assessment of Agonist Efficacy in the μ-Opioid Receptor: Morphine and Fentanyl Elicit Different Activation Patterns.

Over the past two decades, the opioid epidemic in the United States and Canada has evidenced the need for a better understanding of the molecular mechanisms of medications used to fight pain. Morphine and fentanyl are widely used in opiate-mediated analgesia for the treatment of chronic pain. These compounds target the μ-opioid receptor (MOR), a class A G protein-coupled receptor (GPCR). In light of described higher efficacy of fentanyl with respect to morphine, we have performed independent μs-length unbiased molecular dynamics (MD) simulations of MOR complexes with each of these ligands, including the MOR antagonist naltrexone as a negative control. Consequently, MD simulations totaling 58 μs have been conducted to elucidate at the atomic level ligand-specific receptor activity and signal transmission in the MOR. In particular, we have identified stable binding poses of morphine and fentanyl, which interact differently with the MOR. Different ligand-receptor interaction landscapes directly induce sidechain conformational changes of orthosteric pocket residues: Asp149, Tyr150, Gln126, and Lys235. The induced conformations determine Asp149-Tyr328 sidechain-sidechain interactions and Trp295-Ala242 sidechain-backbone H-bond formations, as well as Met153 conformational changes. In addition to differences in ligand binding, different intracellular receptor conformational changes are observed as morphine preferentially activates transmembrane (TM) helices: TM3 and TM5, while fentanyl preferentially activates TM6 and TM7. As conformational changes in TM6 and TM7 are widely described as being the most crucial aspect in GPCR activation, this may contribute to the greater efficacy of fentanyl over morphine. These computationally observed functional differences between fentanyl and morphine may provide new avenues for the design of safer but not weaker opioid drugs because it is desirable to increase the safety of medicines without sacrificing their efficacy.

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Multifocal glioblastoma-two case reports and literature review.

Multifocal glioblastoma is a rare type of glioblastoma with worse prognosis. In this article, we aimed to report two cases of classical multifocal glioblastoma.

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Chronic Scrotal Content Pain: a Review of the Literature and Management Schemes.

Chronic scrotal content pain (CSCP) is a complex condition with multiple etiologies that requires a thorough understanding of its pathophysiology, workup, and treatment options. We performed a comprehensive and contemporary review to augment our current understanding of CSCP.

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Pharmacogenomics and prescription opioid use.

Genome-wide association studies and candidate gene findings suggest that genetic approaches may help in choosing the most appropriate drug and dosage, while preventing adverse drug reactions. This is the field that addresses Precision Medicine: to evaluate variations in the DNA sequence that could be responsible for different individual analgesic response. We review potential gene biomarkers with best overall convergent functional evidence, for opioid use, in pain management. Polymorphisms can modify pharmacodynamics (i.e., mu opioid receptor, ) and pharmacokinetics (i.e., CYP2D6 phenotypes) pathways altering opioid effectiveness, consumption, side effects or additionally, prescription opioid use dependence vulnerability. This review provides a summary of these candidate variants for the translation of genotype into clinically useful information in pain medicine.

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Perioperative glucocorticoid management based on current evidence.

Glucocorticoid preparations, adreno-cortical steroids, with strong anti-inflammatory and immunosuppressive effects, are widely used for treating various diseases. The number of patients exposed to steroid therapy prior to surgery is increasing. When these patients present for surgery, the anesthesiologist must decide whether to administer perioperative steroid supplementation. Stress-dose glucocorticoid administration is required during the perioperative period because of the possibility of failure of cortisol secretion to cope with the increased cortisol requirement due to surgical stress, adrenal insufficiency, hemodynamic instability, and the possibility of adrenal crisis. Therefore, glucocorticoids should be supplemented at the same level as that of normal physiological response to surgical stress by evaluating the invasiveness of surgery and inhibition of the hypothalamus-pituitary-adrenal axis. Various textbooks and research articles recommend the stress-dose of glucocorticoids during perioperative periods. It has been commonly suggested that glucocorticoids should be administered in an amount equivalent to about 100 mg of cortisol for major surgery because it induces approximately 5 times the normal secretion. However, more studies, with appropriate power, regarding the administration of stress-dose glucocorticoids are still required, and evaluation of patients with possible adrenal insufficiency and appropriate glucocorticoid administration based on surgical stress will help improve the prognosis.

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A physiological model of the inflammatory-thermal-pain-cardiovascular interactions during an endotoxin challenge.

Inflammation in response to bacterial endotoxin challenge impacts physiological functions including cardiovascular, thermal, and pain dynamics, but the mechanisms are poorly understood. We develop an innovative mathematical model, incorporating interaction pathways between inflammation and physiological processes observed in response to an endotoxin challenge. We calibrate the model to individual data from 20 subjects in an experimental study of the human inflammatory and physiological responses to endotoxin, and we validate the model against human data from an independent study. Using the model to simulate patient responses to different treatment modalities reveals that a multimodal treatment combining several therapeutic strategies gives the best recovery outcome.

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Outcomes of Open and Endoscopic Repairs of Chronic Partial- and Full-Thickness Proximal Hamstring Tendon Tears: A Multicenter Study With Minimum 2-Year Follow-up.

The preponderance of literature on the repair of proximal hamstring tendon tears focuses on the acute phase (<4 weeks). As such, there is a paucity of data reporting on the outcomes of chronic proximal hamstring tears.

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Resting-state magnetoencephalography source magnitude imaging with deep-learning neural network for classification of symptomatic combat-related mild traumatic brain injury.

Combat-related mild traumatic brain injury (cmTBI) is a leading cause of sustained physical, cognitive, emotional, and behavioral disabilities in Veterans and active-duty military personnel. Accurate diagnosis of cmTBI is challenging since the symptom spectrum is broad and conventional neuroimaging techniques are insensitive to the underlying neuropathology. The present study developed a novel deep-learning neural network method, 3D-MEGNET, and applied it to resting-state magnetoencephalography (rs-MEG) source-magnitude imaging data from 59 symptomatic cmTBI individuals and 42 combat-deployed healthy controls (HCs). Analytic models of individual frequency bands and all bands together were tested. The All-frequency model, which combined delta-theta (1-7 Hz), alpha (8-12 Hz), beta (15-30 Hz), and gamma (30-80 Hz) frequency bands, outperformed models based on individual bands. The optimized 3D-MEGNET method distinguished cmTBI individuals from HCs with excellent sensitivity (99.9 ± 0.38%) and specificity (98.9 ± 1.54%). Receiver-operator-characteristic curve analysis showed that diagnostic accuracy was 0.99. The gamma and delta-theta band models outperformed alpha and beta band models. Among cmTBI individuals, but not controls, hyper delta-theta and gamma-band activity correlated with lower performance on neuropsychological tests, whereas hypo alpha and beta-band activity also correlated with lower neuropsychological test performance. This study provides an integrated framework for condensing large source-imaging variable sets into optimal combinations of regions and frequencies with high diagnostic accuracy and cognitive relevance in cmTBI. The all-frequency model offered more discriminative power than each frequency-band model alone. This approach offers an effective path for optimal characterization of behaviorally relevant neuroimaging features in neurological and psychiatric disorders.

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Targeted Drug Delivery for Chronic Nonmalignant Pain: Longitudinal Data From the Product Surveillance Registry.

To assist in assessment of therapy risks and benefits of targeted drug delivery (TDD) for chronic nonmalignant pain using registry data on product performance, adverse events, and elective device replacement.

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CT diagnostic reference levels based on clinical indications: results of a large-scale European survey.

The objective of this study was to investigate the feasibility of defining diagnostic reference levels (DRLs) on a European basis for specific clinical indications (CIs), within the context of the European Clinical DRLs (EUCLID) European Commission project.

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