National Institutes of Health
  • Bethesda, MD, United States
Recent publications
Radiologists and members-in-training are experiencing higher (and escalating) rates of burnout, resulting in a profound impact on the health of physicians, patients, and the community. Lately, the radiology community has demonstrated a growing awareness of this phenomenon, which has led to emphasis on practicing and promoting wellness. With a myriad of factors contributing to burnout in radiology, a multifaceted approach is pivotal for counteracting burnout and fostering overall well-being, including efforts driven at both organizational and individual levels. This article discusses perspectives from the members of the Early Career Committee at the Society for Advanced Body Imaging (SABI); it explores their beliefs and practical strategies for maintaining personal well-being.
Although linked to esophageal carcinogenesis, the mechanisms by which cigarette smoke mediates initiation and progression of esophageal adenocarcinomas (EAC) have not been fully elucidated. In this study, immortalized esophageal epithelial cells and EAC cells (EACCs) were cultured with or without cigarette smoke condensate (CSC) under relevant exposure conditions. Endogenous levels of microRNA (miR)-145 and lysyl-likeoxidase 2 (LOXL2) were inversely correlated in EAC lines/tumors compared with that in immortalized cells/normal mucosa. The CSC repressed miR-145 and upregulated LOXL2 in immortalized esophageal epithelial cells and EACCs. Knockdown or constitutive overexpression of miR-145 activated or depleted LOXL2, respectively, which enhanced or reduced proliferation, invasion, and tumorigenicity of EACC, respectively. LOXL2 was identified as a novel target of miR-145 as well as a negative regulator of this miR in EAC lines/Barrett's epithelia. Mechanistically, CSC induced recruitment of SP1 to the LOXL2 promoter; LOXL2 upregulation coincided with LOXL2 enrichment and concomitant reduction of H3K4me3 levels within the promoter of miR143HG (host gene for miR-145). Mithramycin downregulated LOXL2 and restored miR-145 expression in EACC and abrogated LOXL2-mediated repression of miR-145 by CSC. These findings implicate cigarette smoke in the pathogenesis of EAC and demonstrate that oncogenic miR-145-LOXL2 axis dysregulation is potentially druggable for the treatment and possible prevention of these malignancies.
NADPH oxidases (NOX’s), and the reactive oxygen species (ROS) they produce, play an important role in host defense, thyroid hormone synthesis, apoptosis, gene regulation, angiogenesis and other processes. However, overproduction of ROS by these enzymes is associated with cardiovascular disease, fibrosis, traumatic brain injury (TBI) and other diseases. Structural similarities between NOX’s have complicated development of specific inhibitors. Here, we report development of NCATS-SM7270, a small molecule optimized from GSK2795039, that inhibited NOX2 in primary human and mouse granulocytes. NCATS-SM7270 specifically inhibited NOX2 and had reduced inhibitory activity against xanthine oxidase in vitro. We also studied the role of several NOX isoforms during mild TBI (mTBI) and demonstrated that NOX2 and, to a lesser extent, NOX1 deficient mice are protected from mTBI pathology, whereas injury is exacerbated in NOX4 knockouts. Given the pathogenic role played by NOX2 in mTBI, we treated mice transcranially with NCATS-SM7270 after injury and revealed a dose-dependent reduction in mTBI induced cortical cell death. This inhibitor also partially reversed cortical damage observed in NOX4 deficient mice following mTBI. These data demonstrate that NCATS-SM7270 is an improved and specific inhibitor of NOX2 capable of protecting mice from NOX2-dependent cell death associated with mTBI.
Among the numerous general anesthetics utilized in rodent surgical procedures, the co-administration of ketamine and xylazine is the current standard for induction and maintenance of surgical planes of anesthesia and pain control. In contrast to classical GABAergic anesthetics, which act to inhibit CNS activity, inducing muscle relaxation, sedation, hypothermia, and brain hypoxia, ketamine and xylazine act through different mechanisms to induce similar effects while also providing potent analgesia. By using three-point thermorecording in freely moving rats, we show that the ketamine-xylazine mixture induces modest brain hyperthermia, resulting from increased intra-cerebral heat production due to metabolic brain activation and increased heat loss due to skin vasodilation. The first effect derives from ketamine, which alone increases brain and body temperatures due to brain metabolic activation and skin vasoconstriction. The second effect derives from xylazine, which increases heat loss due to potent skin vasodilation. By using oxygen sensors coupled with amperometry, we show that the ketamine-xylazine mixture modestly decreases brain oxygen levels that results from relatively weak respiratory depression. This tonic pharmacological effect was preceded by a strong but transient oxygen increase that may result from a stressful injection or unknown, possibly peripheral action of this drug combination. This pattern of physiological effects elicited by the ketamine-xylazine mixture differs from the effects of other general anesthetic drugs, particularly barbiturates.
Keratins are key structural proteins found in skin and other epithelial tissues. Keratins also protect epithelial cells from damage or stress. Fifty-four human keratins were identified and classified into two families, type I and type II. Accumulating studies showed that keratin expression is highly tissue-specific and used as a diagnostic marker for human diseases. Notably, keratin 79 (KRT79) is type II cytokeratin that was identified as regulator of hair canal morphogenesis and regeneration in skin, but its role in liver remains unclear. KRT79 is undetectable in normal mouse but its expression is significantly increased by the PPARA agonist WY-14643 and fenofibrate, and completely abolished in Ppara-null mice. The Krt79 gene has functional PPARA binding element between exon 1 and exon 2. Hepatic Krt79 is regulated by HNF4A and HER2. Moreover, hepatic KRT79 is also significantly elevated by fasting- and high-fat diet-induced stress, and these increases are completely abolished in Ppara-null mice. These findings suggest that hepatic KRT79 is controlled by PPARA and is highly associated with liver damage. Thus, KRT79 may be considered as a diagnostic marker for human liver diseases.
Background: As a potential indicator of equity in research partnerships, we conducted a bibliometric analysis of author affiliations and author order in publications about sub-Saharan Africa published in the journal Sexually Transmitted Diseases. Methods: We identified articles in the journal Sexually Transmitted Diseases that were about sub-Saharan Africa and published from 2011 to 2020. Medical Subject Heading (MeSH) terms in PubMed were used to identity articles about sub-Saharan Africa. Authors with at least one affiliation in sub-Saharan Africa were characterized as sub-Saharan Africa-affiliated authors. Results: Of the 1,439 articles that were published in Sexually Transmitted Diseases from 2011 to 2020, 148 (10%) had a MeSH term for a sub-Saharan African country. Of the 604 authors of these 148 articles, 53 (36%) of the first authors, 493 (53%) of the middle authors, and 58 (40%) of the last authors had a sub-Saharan African affiliation; 13 (8.8%) of the articles had no authors with a sub-Saharan African affiliation. The proportions of sub-Saharan African-affiliated authors in first and last authorship positions did not change significantly from 2011-15 (77 articles) to 2016-20 (71 articles). Conclusions: The underrepresentation of Africans in first and last authorship positions suggests power imbalances in global scientific partnerships. Funders, researchers, editors, publishers, and grant and manuscript reviewers each have roles in promoting equity in global health research. This study may serve as an example for journals to establish benchmarks and monitor progress toward a more equitable research environment.
Background Primary brain tumor (PBT) patients experience higher levels of distress and anxiety than other solid tumor patients, particularly at the time of clinical evaluation when uncertainty about disease status is high (“scanxiety”). There is promising evidence supporting use of virtual reality (VR) to target psychological symptoms in other solid tumor patients, though PBT patients have not been studied extensively in this context. The primary aim of this phase 2 clinical trial is to establish the feasibility of a remote VR-based relaxation intervention for a PBT population, with secondary aims designed to determine preliminary efficacy of improving distress and anxiety symptoms. Methods PBT patients (N = 120) with upcoming MRI scans and clinical appointments who meet eligibility will be recruited to participate in a single arm trial conducted remotely through the NIH. Following completion of baseline assessments, participants will complete a 5-min VR intervention via telehealth using a head-mounted immersive device while under supervision of the research team. Following the intervention, over the course of 1 month patients can use VR at their discretion with follow-up assessments done immediately post-VR intervention, as well as 1 week and 4 weeks later. Additionally, a qualitative phone interview will be conducted to assess patient satisfaction with the intervention. Discussion Use of immersive VR is an innovative interventional approach to target distress and scanxiety symptoms in PBT patients who are at high risk for experiencing these symptoms leading into their clinical appointments. Findings from this study may inform design of a future multicenter randomized VR trial for PBT patients and may aid in development of similar interventions for other oncology populations. Trial Registration (NCT04301089), registered 9 March 2020.
Cerebral blood flow (CBF) is widely used to assess brain function. However, most preclinical CBF studies have been performed under anesthesia, which confounds findings. High spatiotemporal-resolution CBF imaging of awake animals is challenging due to motion artifacts and background noise, particularly for Doppler-based flow imaging. Here, we report ultrahigh-resolution optical coherence Doppler tomography (µODT) for 3D imaging of CBF velocity (CBFv) dynamics in awake mice by developing self-supervised deep-learning for effective image denoising and motion-artifact removal. We compare cortical CBFv in awake vs. anesthetized mice and their dynamic responses in arteriolar, venular and capillary networks to acute cocaine (1 mg/kg, i.v.), a highly addictive drug associated with neurovascular toxicity. Compared with awake, isoflurane (2-2.5%) induces vasodilation and increases CBFv within 2-4 min, whereas dexmedetomidine (0.025 mg/kg, i.p.) does not change vessel diameters nor flow. Acute cocaine decreases CBFv to the same extent in dexmedetomidine and awake states, whereas decreases are larger under isoflurane, suggesting that isoflurane-induced vasodilation might have facilitated detection of cocaine-induced vasoconstriction. Awake mice after chronic cocaine show severe vasoconstriction, CBFv decreases and vascular adaptations with extended diving arteriolar/venular vessels that prioritize blood supply to deeper cortical capillaries. The 3D imaging platform we present provides a powerful tool to study dynamic changes in vessel diameters and morphology alongside CBFv networks in the brain of awake animals that can advance our understanding of the effects of drugs and disease conditions (ischemia, tumors, wound healing).
Math-anxious people consistently underperform in math. The most widely accepted explanation for why this underperformance occurs is that math-anxious people experience heightened anxiety when faced with math, and this in-the-moment anxiety interferes with performance. Surprisingly, this explanation has not been tested directly. Here, using both self-report and physiological indices of anxiety, we directly test how much in-the-moment anxiety explains math-anxious underperformance. Results indicate that in-the-moment anxiety indeed explains why math-anxious people underperform—but only partially, suggesting a need to seriously consider alternative mechanisms. Results also showed that while some highly math-anxious individuals—those with high levels of heart rate variability—experienced less in-the-moment anxiety, they nevertheless performed no better at math. For these individuals, math-anxious underperformance must occur for reasons unrelated to in-the-moment anxiety. More broadly, our findings point to substantial individual heterogeneity in the mechanisms underlying math-anxious underperformance. Accounting for this mechanistic heterogeneity may prove vital for optimally boosting math performance in math-anxious individuals.
BACKGROUND COVID-19 placed a significant burden on the global healthcare system. Strain in critical care capacity has been associated with increased COVID-19-related ICU mortality. This study evaluates the impact of an early warning system and response team implemented on medical floors to safely triage and care for critically ill patients on the floor and preserve ICU capacity. METHODS We conducted a multicenter, retrospective cohort study, comparing outcomes between intervention and control hospitals within a US eight-hospital urban network. Patients hospitalized with COVID-19 pneumonia between April 13 th , 2020 and June 19 th , 2020 were included in the study, which was a time of a regional surge of COVID-19 admissions. An automated, electronic early warning protocol to identify patients with moderate-severe hypoxemia on the medical floors and implement early interventions was implemented at one of the eight hospitals (“the intervention hospital”). RESULTS Among 1024 patients, 403 (39%) were admitted to the intervention hospital and 621 (61%) were admitted to one of the control hospitals. Adjusted for potential confounders, patients at the intervention hospital were less likely to be admitted to the ICU (HR = 0.73, 95% CI 0.53, 1.000, P = .0499) compared to the control hospitals. Patients admitted from the floors to the ICU at the intervention hospital had shorter ICU stay (HR for ICU discharge: 1.74; 95% CI 1.21, 2.51, P = .003). There was no significant difference between intervention and control hospitals in need for mechanical ventilation (OR = 0.93; 95% CI 0.38, 2.31; P = .88) or hospital mortality (OR = 0.79; 95% CI 0.52, 1.18; P = .25). CONCLUSION A protocol to conserve ICU beds by implementing an early warning system with a dedicated response team to manage respiratory distress on the floors reduced ICU admission and was not associated with worse outcomes compared to hospitals that managed similar levels of respiratory distress in the ICU.
Background: Parathyroid cancer (PC) is a rare endocrine neoplasm with high mortality. While surgery is the treatment for patients with the disease, recurrence rates are high, and patients usually succumb to severe hypercalcemia. There is no effective systemic therapy for the disease. Methods: We analyzed the germline DNA of 17 patients with "sporadic" PC and 3 with atypical parathyroid tumors (APT) who did not have germline CDC73 or MEN1 pathogenic variants. Sequencing of available tumor tissue from 14 patients with PC and 2 with APT was also performed (including two patients with no available germline DNA). In addition, sporadic parathyroid adenomas from 74 patients were analyzed for FLCN variants. Findings: We identified germline FLCN variants in three unrelated patients with PC. The two frameshift variants have been described in patients with Birt-Hogg-Dubé (BHD) syndrome while the pathogenicity of the missense variant c.124G > C (p.G42R) has not been definitively established. Functional analysis of the missense variant showed a potential impact on post-translational modification. All three patients with germline FLCN variants were noted to have renal cysts and two had lung cysts, features associated with BHD syndrome. Somatic FLCN variants were identified in tumors from 2 (one APT) of 16 patients with PC/APT and in none of the 74 sporadic parathyroid adenomas. No second hits in FLCN were noted on sequencing however, LOH at the locus was demonstrated in 2 of 3 patients with identified germline FLCN variant. Conclusion: The finding of FLCN variants associated with PC may provide the foundation for the development of therapy for this malignancy.
P2X receptor channels are trimeric ATP-activated ion channels expressed in neuronal and non-neuronal cells that are attractive therapeutic targets for human disorders. Seven subtypes of P2X receptor channels have been identified in mammals that can form both homomeric and heteromeric channels. P2X1-4 and P2X7 receptor channels are cation-selective, whereas P2X5 has been reported to have both cation and anion permeability. P2X receptor channel structures reveal that each subunit is comprised of two transmembrane helices, with both N-and C-termini on the intracellular side of the membrane and a large extracellular domain that contains the ATP binding sites at subunit interfaces. Recent structures of ATP-bound P2X receptors with the activation gate open reveal the unanticipated presence of a cytoplasmic cap over the central ion permeation pathway, leaving lateral fenestrations that may be largely buried within the membrane as potential pathways for ions to permeate the intracellular end of the pore. In the present study, we identify a critical residue within the intracellular lateral fenestrations that is readily accessible to thiol-reactive compounds from both sides of the membrane and where substitutions influence the relative permeability of the channel to cations and anions. Taken together, our results demonstrate that ions can enter or exit the internal pore through lateral fenestrations that play a critical role in determining the ion selectivity of P2X receptor channels.
Methicillin-resistant Staphylococcus aureus (MRSA) remains a significant problem for human and animal health and can negatively affect the health status of macaques and other nonhuman primates (NHP) in research colonies. However, few publications provide guidance on the prevalence, genotype, or risk factors for macaques with MRSA and even fewer on how to effectively respond to MRSA once identified in a population. After having a clinical case of MRSA in a rhesus macaque, we sought to determine the MRSA carrier prevalence, risk factors, and genotypes of MRSA in a population of research NHPs. Over a 6-wk period in 2015, we collected nasal swabs from 298 NHPs. MRSA was isolated from 28% (n = 83). We then reviewed each macaque's medical record for a variety of variables including animal housing room, sex, age, number of antibiotic courses, number of surgical interventions, and SIV status. Analysis of these data suggests that MRSA carriage is associated with the room location, age of the animal, SIV status, and the number of antibiotic courses. We used multilocus sequence typing and spa typing on a subset of MRSA and MSSA isolates to determine whether the MRSA present in NHPs was comparable with common human strains. Two MRSA sequence types were predominant: ST188 and a novel MRSA genotype, neither of which is a common human isolate in the United States. We subsequently implemented antimicrobial stewardship practices (significantly reducing antimicrobial use) and then resampled the colony in 2018 and found that MRSA carriage had fallen to 9% (26/285). These data suggest that, as in humans, macaques may have a high carrier status of MRSA despite low clinically apparent disease. Implementing strategic antimicrobial stewardship practices resulted in a marked reduction in MRSA carriage in the NHP colony, highlighting the importance of limiting antimicrobial use when possible.
Glioneuronal tumors are a heterogenous group of CNS neoplasms that can be challenging to accurately diagnose. Molecular methods are highly useful in classifying these tumors—distinguishing precise classes from their histological mimics and identifying previously unrecognized types of tumors. Using an unsupervised visualization approach of DNA methylation data, we identified a novel group of tumors (n = 20) that formed a cluster separate from all established CNS tumor types. Molecular analyses revealed ATRX alterations (in 16/16 cases by DNA sequencing and/or immunohistochemistry) as well as potentially targetable gene fusions involving receptor tyrosine-kinases (RTK; mostly NTRK1-3) in all of these tumors (16/16; 100%). In addition, copy number profiling showed homozygous deletions of CDKN2A/B in 55% of cases. Histological and immunohistochemical investigations revealed glioneuronal tumors with isomorphic, round and often condensed nuclei, perinuclear clearing, high mitotic activity and microvascular proliferation. Tumors were mainly located supratentorially (84%) and occurred in patients with a median age of 19 years. Survival data were limited (n = 18) but point towards a more aggressive biology as compared to other glioneuronal tumors (median progression-free survival 12.5 months). Given their molecular characteristics in addition to anaplastic features, we suggest the term glioneuronal tumor with ATRX alteration, kinase fusion and anaplastic features (GTAKA) to describe these tumors. In summary, our findings highlight a novel type of glioneuronal tumor driven by different RTK fusions accompanied by recurrent alterations in ATRX and homozygous deletions of CDKN2A/B. Targeted approaches such as NTRK inhibition might represent a therapeutic option for patients suffering from these tumors.
Opioids induce respiratory depression resulting in coma or even death during overdose. Naloxone, an opioid antagonist, is the gold standard reversal agent for opioid intoxication, but this treatment is often less successful for fentanyl. While low dosing is thought to be a factor limiting naloxone's efficacy, the timing between fentanyl exposure and initiation of naloxone treatment may be another important factor. Here, we used oxygen sensors coupled with amperometry to examine the pattern of oxygen responses in the brain and periphery induced by intravenous fentanyl in freely moving rats. At both doses (20 and 60 μg/kg), fentanyl induced a biphasic brain oxygen response-a rapid, strong, and relatively transient decrease (8-12 min) followed by a weaker and prolonged increase. In contrast, fentanyl induced stronger and more prolonged monophasic oxygen decreases in the periphery. When administered before fentanyl, intravenous naloxone (0.2 mg/kg) fully blocked the hypoxic effects of moderate-dose fentanyl in both the brain and periphery. However, when injected 10 min after fentanyl, when most of hypoxia has already ceased, naloxone had minimal effect on central and peripheral oxygen levels, but at a higher dose, it strongly attenuated hypoxic effects in the periphery with only a transient brain oxygen increase associated with behavioral awakening. Therefore, due to the rapid, strong but transient nature of fentanyl-induced brain hypoxia, the time window when naloxone can attenuate this effect is relatively short. This timing limitation is critical, making naloxone most effective when used quickly and less effective when used during the post-hypoxic comatose state after brain hypoxia has already ceased and harm for neural cells already done.
Neutrophilic inflammation is a hallmark of many monogenic autoinflammatory diseases; pathomechanisms that regulate extravasation of damaging immune cells into surrounding tissues are poorly understood. Here we identified three unrelated boys with perinatal-onset of neutrophilic cutaneous small vessel vasculitis and systemic inflammation. Two patients developed liver fibrosis in their first year of life. Next-generation sequencing identified two de novo truncating variants in the Src-family tyrosine kinase, LYN, p.Y508*, p.Q507* and a de novo missense variant, p.Y508F, that result in constitutive activation of Lyn kinase. Functional studies revealed increased expression of ICAM-1 on induced patient-derived endothelial cells (iECs) and of β2-integrins on patient neutrophils that increase neutrophil adhesion and vascular transendothelial migration (TEM). Treatment with TNF inhibition improved systemic inflammation; and liver fibrosis resolved on treatment with the Src kinase inhibitor dasatinib. Our findings reveal a critical role for Lyn kinase in modulating inflammatory signals, regulating microvascular permeability and neutrophil recruitment, and in promoting hepatic fibrosis.
Background: The shared inherited genetic contribution to risk of different cancers is not fully known. In this study, we leverage results from twelve cancer genome-wide association studies (GWAS) to quantify pair-wise genome-wide genetic correlations across cancers and identify novel cancer susceptibility loci. Methods: We collected GWAS summary statistics for twelve solid cancers based on 376,759 cancer cases and 532,864 controls of European ancestry. The included cancer types were breast, colorectal, endometrial, esophageal, glioma, head and neck, lung, melanoma, ovarian, pancreatic, prostate, and renal cancers. We conducted cross-cancer GWAS and transcriptome-wide association studies (TWAS) to discover novel cancer susceptibility loci. Finally, we assessed the extent of variant-specific pleiotropy among cancers at known and newly identified cancer susceptibility loci. Results: We observed wide-spread but modest genome-wide genetic correlations across cancers. In cross-cancer GWAS and TWAS, we identified 15 novel cancer susceptibility loci. Additionally, we identified multiple variants at 77 distinct loci with strong evidence of being associated with at least two cancer types by testing for pleiotropy at known cancer susceptibility loci. Conclusions: Overall, these results suggest that some genetic risk variants are shared among cancers, though much of cancer heritability is cancer- and thus tissue-specific. The increase in statistical power associated with larger sample sizes in cross-disease analysis allows for the identification of novel susceptibility regions. Future studies incorporating data on multiple cancer types are likely to identify additional regions associated with the risk of multiple cancer types.
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6,196 members
Rajakannan Thiyagu
Ron Thomas Varghese
  • National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Anandakumar Shunmugavel
  • National Institute of Biomedical Imaging and Bioengineering (NIBIB)
Randy J. Chandler
  • National Human Genome Research Institute (NHGRI): National Institute of Health
9000 Rockville Pike, 20892, Bethesda, MD, United States
Head of institution
Francis Collins, M.D., Ph.D