THE NEUROENDOTHELIAL AXIS IN TRAUMATIC BRAIN INJURY: MECHANISMS OF MULTIORGAN DYSFUNCTION, NOVEL THERAPIES, AND FUTURE DIRECTIONS.

ABSTRACT: Severe traumatic brain injury (TBI) often initiates a systemic inflammatory response syndrome, which can potentially culminate into multiorgan dysfunction. A central player in this cascade is endotheliopathy, caused by perturbations in homeostatic mechanisms governed by endothelial cells due to injury-induced coagulopathy, heightened sympathoadrenal response, complement activation, and proinflammatory cytokine release. Unique to TBI is the potential disruption of the blood-brain barrier, which may expose neuronal antigens to the peripheral immune system and permit neuroinflammatory mediators to enter systemic circulation, propagating endotheliopathy systemically. This review aims to provide comprehensive insights into the "neuroendothelial axis" underlying endothelial dysfunction after TBI, identify potential diagnostic and prognostic biomarkers, and explore therapeutic strategies targeting these interactions, with the ultimate goal of improving patient outcomes after severe TBI.

Finding the Right Balance: Partial REBOA in a Swine Model of Uncontrolled Vascular Injury.

BACKGROUND: We have previously shown that partial REBOA (pREBOA) deployment in the thoracic aorta is safe for 2 to 4 hours, but it is unclear whether the distal blood flow after partial aortic occlusion would lead to ongoing hemorrhage. The objective of this study was to evaluate the hemostatic efficacy of pREBOA in a model of uncontrolled vascular injury. STUDY DESIGN: Female Yorkshire swine (n = 10, 40 to 45 kg) were anesthetized and instrumented. A through-and-through injury was created in the common iliac artery. The animals were randomly assigned to: (1) pREBOA-PRO deployment after 3 minutes and (2) control. Both groups were given normal saline resuscitation for hypotension. The pREBOA was adjusted to partial occlusion (distal mean arterial pressure of 30 mmHg), and then left without titration for 2 hours. Then, fresh frozen plasma was transfused and the vessel repaired. The balloon was deflated and the animals were monitored for 2 hours. In the critical care period, 2 L of normal saline was infused, norepinephrine was given for mean arterial pressure ≤55, and electrolytes and acidosis were corrected. Organs were examined for gross and histologic evidence of ischemic injuries. The primary endpoint was post-inflation blood loss. RESULTS: All the pREBOA animals survived until the end, whereas control animals had a mean survival time of 38.2 minutes (p < 0.05). The pREBOA group showed significantly less bleeding after balloon deployment (93.8 vs 1,980.0 mL, p < 0.05), and had appropriate lactate clearance, with minimal histologic distal organ ischemia. CONCLUSIONS: Partial aortic occlusion with the newly designed balloon can achieve the desired balance between effective hemorrhage control and adequate distal flow, without a need for ongoing balloon titration.

Effect of Pulsed Low-Intensity Ultrasonography on Symptom Relief and Tibiofemoral Articular Cartilage Thickness Among Veterans Affairs Enrollees With Knee Osteoarthritis: A Randomized Clinical Trial.

Importance: Osteoarthritis (OA) is a major cause of disability in the US, with no approved treatments to slow progression, but animal models suggest that pulsed low-intensity ultrasonography (PLIUS) may promote cartilage growth. Objective: To evaluate the efficacy of PLIUS in providing symptom reduction and decreased loss of tibiofemoral cartilage thickness in patients with knee OA. Design, Setting, and Participants: A phase 2A, sham-controlled, parallel, double-blind randomized clinical trial was conducted at 2 Veterans Affairs hospitals in Salt Lake City, Utah, and San Diego, California, from May 22, 2015, to January 31, 2019. Data were analyzed from June 27, 2020, to October 20, 2020. Participants recruited through the US Department of Veterans Affairs (N = 132) with clinical and radiographic evidence of early knee OA were randomly assigned to receive PLIUS or a sham device, self-administered for 20 minutes daily over the medial compartment of the knee. All enrollees participated in a 4-week prerandomization sham run-in period, followed by a 48-week treatment period. Randomization was stratified by study site and Kellgren-Lawrence grades 1 (n = 15), 2 (n = 51), and 3 (n = 66). Intervention: Participants either received 48 weeks of PLIUS or sham ultrasonography. Main Outcomes and Measures: The trial incorporated 2 coprimary outcomes: symptomatic improvement assessed by Outcome Measures in Rheumatology Clinical Trials-Osteoarthritis Research Society International Responder Criteria (ie, met if either >50% improvement in pain and function with at least a 20% absolute improvement of at least 2 of the following 3 factors: improvement by at least 20% [pain, function, and patient global assessment] with at least a 10-mm absolute improvement), and cartilage preservation assessed as change in central medial femoral condyle cartilage thickness by magnetic resonance imaging. Intention-to-treat analysis was used. Results: The mean (SD) participant age was 63.6 (10.7) years and 119 were men (90.2%). The mean (SD) duration of OA symptoms was 13.4 (12.3) years. In the PLIUS group, 70.4% (95% CI, 58.2%-82.6%) of the participants experienced symptomatic improvement, compared with 67.3% (95% CI, 54.9%-79.7%) of participants in the sham group (P = .84); there was no statistically significant difference in response rates between the treatment groups, and the between-group rate difference of 3.1% (95% CI, -14.3% to 20.5%) did not meet the predefined 10% threshold for clinically significant symptomatic improvement from application of PLIUS. At 48 weeks of treatment, central medial femoral condyle cartilage thickness decreased by a mean (SD) of 73.8 (168.1) µm in the PLIUS group and by 42.2 (297.0) µm in the sham group. This 48-week mean change between the 2 groups did not reach statistical significance (P = .44), and the between-group 48-week difference of -31.7 µm (95% CI, -129.0 µm to 65.7 µm) did not meet the predefined threshold. There were 99 nonserious adverse events in the PLIUS group and 89 in the sham group during the trial. No serious adverse events were deemed related to the study device. Conclusions and Relevance: PLIUS, as implemented in this study, demonstrated neither symptomatic benefit nor a decrease in loss of tibiofemoral cartilage thickness in knee OA. Trial Registration: ClinicalTrials.gov Identifier: NCT02034409.

Regional Contribution of Previable Infant Deaths to Infant Mortality Rates in the United States.

OBJECTIVE: Lack of standardization of infant mortality rate (IMR) calculation between regions in the United States makes comparisons potentially biased. This study aimed to quantify differences in the contribution of early previable live births (<20 weeks) to U.S. regional IMR. STUDY DESIGN: Population-based cohort study of all U.S. live births and infant deaths recorded between 2007 and 2014 using Centers for Disease Control and Prevention's (CDC's) WONDER database linked birth/infant death records (births from 17-47 weeks). Proportion of infant deaths attributable to births <20 vs. 20 to 47 weeks, and difference (ΔIMR) between reported and modified (births ≥20 weeks) IMRs were compared across four U.S. census regions (North, South, Midwest, and West). RESULTS: Percentages of infant deaths attributable to birth <20 weeks were 6.3, 6.3, 5.3, and 4.1% of total deaths for Northeast, Midwest, South, and West, respectively, p < 0.001. Contribution of < 20-week deaths to each region's IMR was 0.34, 0.42, 0.37, and 0.2 per 1,000 live births. Modified IMR yielded less regional variation with IMRs of 5.1, 6.2, 6.6, and 4.9 per 1,000 live births. CONCLUSION: Live births at <20 weeks contribute significantly to IMR as all result in infant death. Standardization of gestational age cut-off results in more consistent IMRs among U.S. regions and would result in U.S. IMR rates exceeding the healthy people 2020 goal of 6.0 per 1,000 live births.

Gender and ethnic diversity in academic general surgery department leadership.

BACKGROUND: Diversity in surgery has been shown to improve mentorship and patient care. Diversity has improved among general surgery (GS) trainees but is not the case for departmental leadership. We analyzed the race and gender distributions across leadership positions at academic GS programs. METHODS: Academic GS programs (n = 118) listed by the Fellowship and Residency Electronic Interactive Database Access system were included. Leadership positions were ascertained from department websites. Gender and race were determined through publicly provided data. RESULTS: Ninety-two (79.3%) department chairs were white and 99 (85.3%) were men. Additionally, 88 (74.6%) program directors and 34 (77.3%) vice-chairs of education were men. A higher proportion of associate program directors were women (38.5%). Of 787 division-chiefs, 73.4% were white. Only trauma had >10% representation from minority surgeons. Women represented >10% of division chiefs in colorectal, thoracic, pediatric, and plastic/burn surgery. CONCLUSION: Diversity among GS trainees is not yet reflected in departmental leadership. Effort is needed to improve disparities in representation across leadership roles.

The impact of sleeve gastrectomy on renal function in patients with chronic kidney disease varies with severity of renal insufficiency.

BACKGROUND: Although laparoscopic sleeve gastrectomy is known, in general, to improve renal function in patients with obesity and chronic kidney disease (CKD), its effect on estimated glomerular filtration rate (eGFR) stratified by the stage of CKD is less clear. OBJECTIVES: We aimed to evaluate the impact of sleeve gastrectomy on renal function in a stratified cohort of patients with CKD. SETTING: University Hospital. METHODS: We performed a retrospective review of 1932 patients who met National Institutes of Health's guidelines for metabolic surgery and underwent laparoscopic sleeve gastrectomy performed by 1 of 3 surgeons. One hundred sixty-four patients with CKD stages 1 through 4 were identified. RESULTS: Mean follow-up period was 1.57 ± 1.0 years. Mean age was 56.4 ± 9.9 years with a preoperative body mass index of 47 ± 9 kg/m2, which decreased to 38.9 ± 8.7 kg/m2 at most recent follow-up (P < .001). In the cohort of patients with diabetes, significant decreases were observed in mean glycated hemoglobin level, daily number of oral hypoglycemics, and daily long acting insulin use (P < .001 each). Of 67 patients with diabetes, 34.3% (n = 24) achieved complete remission. In patients with hypertension, average daily number of antihypertensives decreased (P < .001) and 22.3% (n = 31) of 133 patients with hypertension discontinued all antihypertensives. Patients with CKD stages 2, 3a, and 3b showed significant improvement in eGFR. Reinforcing this evidence of improvement, patients with CKD 3a and 3b were more likely to downstage disease compared with those with CKD 4 (58.1% versus 73.1% versus 22.7%, respectively) (P < .001). CONCLUSION: Renal function, as measured by eGFR, in patients with stages 1 and 4 CKD did not improve after laparoscopic sleeve gastrectomy; in contrast, eGFR in patients with CKD stages 2 and 3 significantly improved. Early surgical referral and intervention may be important in achieving the greatest improvement in eGFR and possibly delaying or reversing progression to end-stage renal disease.

Circadian Clock, Time-Restricted Feeding and Reproduction.

The goal of this review was to seek a better understanding of the function and differential expression of circadian clock genes during the reproductive process. Through a discussion of how the circadian clock is involved in these steps, the identification of new clinical targets for sleep disorder-related diseases, such as reproductive failure, will be elucidated. Here, we focus on recent research findings regarding circadian clock regulation within the reproductive system, shedding new light on circadian rhythm-related problems in women. Discussions on the roles that circadian clock plays in these reproductive processes will help identify new clinical targets for such sleep disorder-related diseases.

Effect of slice excitation profile on ungated steady state cardiac perfusion imaging.

In cardiac perfusion imaging, choice of flip angle is an important factor for steady state acquisition. This work focuses on presenting an analytical framework for understanding how non-ideal slice excitation profiles affect contrast in ungated 2D steady state cardiac perfusion studies, and to study a technique for estimating flip angle that maximizes enhanced/unenhanced myocardial contrast-to-noise ratio (CNR) in single slice and multi-slice acquisitions. A numerical simulation of ungated 2D golden ratio radial spoiled gradient echo (SPGR) was created that takes into consideration the actual (Bloch simulated) slice excitation profile. The effect of slice excitation profile on myocardial CNR as a function of flip angle was assessed in phantoms and in-vivo. For fast RF pulses, the flip angle that yields maximum CNR (considering the actual slice excitation profile) was considerably higher than expected, assuming an ideal excitation. The simulation framework presented accurately predicts the flip angle yielding maximum CNR when the actual slice excitation profile is taken into consideration. The prescribed flip angle for optimal contrast in ungated 2D steady-state SPGR cardiac perfusion studies can vary significantly from that calculated when an ideal slice excitation profile is assumed. Consideration of the actual slice excitation can yield a more optimal flip angle estimate in both the single slice and multi-slice cases.

Student Response Systems and Learning: Perceptions of the Student.

To assess student perception of learning and use of a student response system (SRS) as a teaching/learning strategy. Survey methods were used to explore student perceptions of learning and use of student response systems as a pedagogical strategy. Fifty-nine graduate students participated in the survey post completion of two graduate intervention courses. Overall, there was a positive response to the use of SRS's in the classroom. All of the students (100%) recommended the continued use of the clickers for various reasons. The primary benefit reported by students related to providing immediate feedback, the opportunity to manipulate and revisit the content, and the ability to check for understanding within a class session. Students recommended the continued use of the SRS in classes to support acquisition of content and exam preparation. The student reported technology difficulties as the only the negative to SRS use in the classroom. Instructor perception was that the addition of the SRS devices added a new way to interact with the students. Suggestions for incorporating the use of a SRS devices into classroom instruction are offered.

Quantitative sodium magnetic resonance imaging of cartilage, muscle, and tendon.

Sodium magnetic resonance imaging (MRI), or imaging of the 23Na nucleus, has been under exploration for several decades, and holds promise for potentially revealing additional biochemical information about the health of tissues that cannot currently be obtained from conventional hydrogen (or proton) MRI. This additional information could serve as an important complement to conventional MRI for many applications. However, despite these exciting possibilities, sodium MRI is not yet used routinely in clinical practice, and will likely remain strictly in the domain of exploratory research for the coming decade. This paper begins with a technical overview of sodium MRI, including the nuclear magnetic resonance (NMR) signal characteristics of the sodium nucleus, the challenges associated with sodium MRI, and the specialized pulse sequences, hardware, and reconstruction techniques required. Various applications of sodium MRI for quantitative analysis of the musculoskeletal system are then reviewed, including the non-invasive assessment of cartilage degeneration in vivo, imaging of tendinopathy, applications in the assessment of various muscular pathologies, and assessment of muscle response to exercise.

Quantitative techniques for musculoskeletal MRI at 7 Tesla.

Whole-body 7 Tesla MRI scanners have been approved solely for research since they appeared on the market over 10 years ago, but may soon be approved for selected clinical neurological and musculoskeletal applications in both the EU and the United States. There has been considerable research work on musculoskeletal applications at 7 Tesla over the past decade, including techniques for ultra-high resolution morphological imaging, 3D T2 and T2* mapping, ultra-short TE applications, diffusion tensor imaging of cartilage, and several techniques for assessing proteoglycan content in cartilage. Most of this work has been done in the knee or other extremities, due to technical difficulties associated with scanning areas such as the hip and torso at 7 Tesla. In this manuscript, we first provide some technical context for 7 Tesla imaging, including challenges and potential advantages. We then review the major quantitative MRI techniques being applied to musculoskeletal applications on 7 Tesla whole-body systems.

Sodium MRI radiofrequency coils for body imaging.

The proliferation of high-field whole-body systems, advances in gradient performance and refinement of signal-to-noise ratio (SNR)-efficient short-TE sequences suitable for sodium imaging have led to a resurgence of interest in sodium imaging for body applications. With this renewed interest has come increased demand for SNR-efficient sodium coils. Efficient coils can significantly increase SNR in sodium imaging, allowing higher resolutions and/or shorter scan times. In this work, we focus on body imaging applications of sodium MRI, and review developments in MRI radiofrequency (RF) coil topologies for sodium imaging. We first provide a brief discussion of RF coil design considerations in sodium imaging. This is followed by an overview of common coil topologies, their advantages and disadvantages, and examples of each.

MRI evaluation of spontaneous intervertebral disc degeneration in the alpaca cervical spine.

Animal models have historically provided an appropriate benchmark for understanding human pathology, treatment, and healing, but few animals are known to naturally develop intervertebral disc degeneration. The study of degenerative disc disease and its treatment would greatly benefit from a more comprehensive, and comparable animal model. Alpacas have recently been presented as a potential large animal model of intervertebral disc degeneration due to similarities in spinal posture, disc size, biomechanical flexibility, and natural disc pathology. This research further investigated alpacas by determining the prevalence of intervertebral disc degeneration among an aging alpaca population. Twenty healthy female alpacas comprised two age subgroups (5 young: 2-6 years; and 15 older: 10+ years) and were rated according to the Pfirrmann-grade for degeneration of the cervical intervertebral discs. Incidence rates of degeneration showed strong correlations with age and spinal level: younger alpacas were nearly immune to developing disc degeneration, and in older animals, disc degeneration had an increased incidence rate and severity at lower cervical levels. Advanced disc degeneration was present in at least one of the cervical intervertebral discs of 47% of the older alpacas, and it was most common at the two lowest cervical intervertebral discs. The prevalence of intervertebral disc degeneration encourages further investigation and application of the lower cervical spine of alpacas and similar camelids as a large animal model of intervertebral disc degeneration.

RNAi screen identifies Brd4 as a therapeutic target in acute myeloid leukaemia.

Epigenetic pathways can regulate gene expression by controlling and interpreting chromatin modifications. Cancer cells are characterized by altered epigenetic landscapes, and commonly exploit the chromatin regulatory machinery to enforce oncogenic gene expression programs. Although chromatin alterations are, in principle, reversible and often amenable to drug intervention, the promise of targeting such pathways therapeutically has been limited by an incomplete understanding of cancer-specific dependencies on epigenetic regulators. Here we describe a non-biased approach to probe epigenetic vulnerabilities in acute myeloid leukaemia (AML), an aggressive haematopoietic malignancy that is often associated with aberrant chromatin states. By screening a custom library of small hairpin RNAs (shRNAs) targeting known chromatin regulators in a genetically defined AML mouse model, we identify the protein bromodomain-containing 4 (Brd4) as being critically required for disease maintenance. Suppression of Brd4 using shRNAs or the small-molecule inhibitor JQ1 led to robust antileukaemic effects in vitro and in vivo, accompanied by terminal myeloid differentiation and elimination of leukaemia stem cells. Similar sensitivities were observed in a variety of human AML cell lines and primary patient samples, revealing that JQ1 has broad activity in diverse AML subtypes. The effects of Brd4 suppression are, at least in part, due to its role in sustaining Myc expression to promote aberrant self-renewal, which implicates JQ1 as a pharmacological means to suppress MYC in cancer. Our results establish small-molecule inhibition of Brd4 as a promising therapeutic strategy in AML and, potentially, other cancers, and highlight the utility of RNA interference (RNAi) screening for revealing epigenetic vulnerabilities that can be exploited for direct pharmacological intervention.

An integrated approach to dissecting oncogene addiction implicates a Myb-coordinated self-renewal program as essential for leukemia maintenance.

Although human cancers have complex genotypes and are genomically unstable, they often remain dependent on the continued presence of single-driver mutations-a phenomenon dubbed "oncogene addiction." Such dependencies have been demonstrated in mouse models, where conditional expression systems have revealed that oncogenes able to initiate cancer are often required for tumor maintenance and progression, thus validating the pathways they control as therapeutic targets. Here, we implement an integrative approach that combines genetically defined mouse models, transcriptional profiling, and a novel inducible RNAi platform to characterize cellular programs that underlie addiction to MLL-AF9-a fusion oncoprotein involved in aggressive forms of acute myeloid leukemia (AML). We show that MLL-AF9 contributes to leukemia maintenance by enforcing a Myb-coordinated program of aberrant self-renewal involving genes linked to leukemia stem cell potential and poor prognosis in human AML. Accordingly, partial and transient Myb suppression precisely phenocopies MLL-AF9 withdrawal and eradicates aggressive AML in vivo without preventing normal myelopoiesis, indicating that strategies to inhibit Myb-dependent aberrant self-renewal programs hold promise as effective and cancer-specific therapeutics. Together, our results identify Myb as a critical mediator of oncogene addiction in AML, delineate relevant Myb target genes that are amenable to pharmacologic inhibition, and establish a general approach for dissecting oncogene addiction in vivo.

Toolkit for evaluating genes required for proliferation and survival using tetracycline-regulated RNAi.

Short hairpin RNAs (shRNAs) are versatile tools for analyzing loss-of-function phenotypes in vitro and in vivo. However, their use for studying genes involved in proliferation and survival, which are potential therapeutic targets in cancer and other diseases, is confounded by the strong selective advantage of cells in which shRNA expression is inefficient. We therefore developed a toolkit that combines Tet-regulated miR30-shRNA technology, robust transactivator expression and two fluorescent reporters to track and isolate cells with potent target knockdown. We demonstrated that this system improves the study of essential genes and was sufficiently robust to eradicate aggressive cancer in mice by suppressing a single gene. Further, we applied this system for in vivo negative-selection screening with pooled shRNAs and propose a streamlined, inexpensive workflow that will facilitate the use of RNA interference (RNAi) for the identification and evaluation of essential therapeutic targets.