Isabel G. Newton

Glycogen synthase kinase 3β missplicing contributes to leukemia stem cell generation

Recent evidence suggests that a rare population of self-renewing cancer stem cells (CSC) is responsible for cancer progression and therapeutic resistance. Chronic myeloid leukemia (CML) represents an important paradigm for understanding the genetic and epigenetic events involved in CSC production. CML progresses from a chronic phase (CP) in hematopoietic stem cells (HSC) that harbor the BCR-ABL translocation, to blast crisis (BC), characterized by aberrant activation of β-catenin within granulocyte-macrophage progenitors (GMP). A major barrier to predicting and inhibiting blast crisis transformation has been the identification of mechanisms driving β-catenin activation. Here we show that BC CML myeloid progenitors, in particular GMP, serially transplant leukemia in immunocompromised mice and thus are enriched for leukemia stem cells (LSC). Notably, cDNA sequencing of Wnt/β-catenin pathway regulatory genes, including adenomatous polyposis coli, GSK3β, axin 1, β-catenin, lymphoid enhancer factor-1, cyclin D1, and c-myc, revealed a novel in-frame splice deletion of the GSK3β kinase domain in the GMP of BC samples that was not detectable by sequencing in blasts or normal progenitors. Moreover, BC CML progenitors with misspliced GSK3β have enhanced β-catenin expression as well as serial engraftment potential while reintroduction of full-length GSK3β reduces both in vitro replating and leukemic engraftment. We propose that CP CML is initiated by BCR-ABL expression in an HSC clone but that progression to BC may include missplicing of GSK3β in GMP LSC, enabling unphosphorylated β-catenin to participate in LSC self-renewal. Missplicing of GSK3β represents a unique mechanism for the emergence of BC CML LSC and might provide a novel diagnostic and therapeutic target.

Caloric restriction and age affect synaptic proteins in hippocampal CA3 and spatial learning ability.

Caloric restriction (CR) is a daily reduction of total caloric intake without a decrease in micronutrients or disproportionate reduction of any one dietary component. CR can increase lifespan reliably in a wide range of species and appears to counteract some aspects of the aging process throughout the body. The effects on the brain are less clear, but moderate CR seems to attenuate age-related cognitive decline. Thus, we determined the effects of age and CR on key synaptic proteins in the CA3 region of the hippocampus and whether these changes were correlated with differences in behavior on a hippocampal-dependent learning and memory task. We observed an overall, age-related decline in the NR1, N2A and N2B subunits of the N-methyl-d-aspartate (NMDA)-type and the GluR1 and GluR2 subunits of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole proprionic acid (AMPA)-type ionotropic glutamate receptors. Interestingly, we found that CR initially lowers the glutamate receptor subunit levels as compared to young AL animals, and then stabilizes the levels across lifespan. Synaptophysin, a presynaptic vesicle protein, showed a similar pattern. We also found that both CR and ad libitum (AL) fed animals exhibited age-related cognitive decline on the Morris water maze task. However, AL animals declined between young and middle age, and between middle age and old, whereas CR rats only declined between young and middle age. Thus, the decrease in key synaptic proteins in CA3 and cognitive decline occurring across lifespan are stabilized by CR. This age-related decrease and CR-induced stabilization are likely to affect CA3 synaptic plasticity and, as a result, hippocampal function.

Caloric restriction eliminates the aging-related decline in NMDA and AMPA receptor subunits in the rat hippocampus and induces homeostasis

Caloric restriction (CR) extends life span and ameliorates the aging-related decline in hippocampal-dependent cognitive function. In the present study, we compared subunit levels of NMDA and AMPA types of the glutamate receptor and quantified total synapses and multiple spine bouton (MSB) synapses in hippocampal CA1 from young (10 months), middle-aged (18 months), and old (29 months) Fischer 344xBrown Norway rats that were ad libitum (AL) fed or caloric restricted (CR) from 4 months of age. Each of these parameters has been reported to be a potential contributor to hippocampal function. Western blot analysis revealed that NMDA and AMPA receptor subunits in AL animals decrease between young and middle age to levels that are present at old age. Interestingly, young CR animals have significantly lower levels of glutamate receptor subunits than young AL animals and those lower levels are maintained across life span. In contrast, stereological quantification indicated that total synapses and MSB synapses are stable across life span in both AL and CR rats. These results indicate significant aging-related losses of hippocampal glutamate receptor subunits in AL rats that are consistent with altered synaptic function. CR eliminates that aging-related decline by inducing stable NMDA and AMPA receptor subunit levels.

Caloric restriction does not reverse aging-related changes in hippocampal BDNF.

Caloric restriction (CR) can attenuate the aging-related decline in learning and memory in rats. Understanding the mechanisms underlying this effect could lead to therapies for human memory impairment. We tested the hypotheses that aging is associated with a decline in hippocampal brain-derived neurotrophic factor (BDNF), a growth factor that enhances learning and memory, and that CR increases hippocampal BDNF. We compared BDNF protein levels in hippocampal subregions of young, middle-aged and old rats fed CR or ad libitum (AL) diets. Mean BDNF levels in the dentate gyrus and CA3 did not differ with diet but increased with age. In CA1, BDNF levels were slightly higher in CR than AL rats at middle and old age but did not change across lifespan. These data suggest that mnemonic impairments with age do not reflect a decrease in hippocampal BDNF. Furthermore, if CRs attenuation of aging-related memory changes is mediated by BDNF, then it must be through a small, CA1-specific increase and does not involve reversal of an aging-related decline in BDNF.

Effects of aging and caloric restriction on dentate gyrus synapses and glutamate receptor subunits

Caloric restriction (CR) attenuates aging-related degenerative processes throughout the body. It is less clear, however, whether CR has a similar effect in the brain, particularly in the hippocampus, an area important for learning and memory processes that often are compromised in aging. In order to evaluate the effect of CR on synapses across lifespan, we quantified synapses stereologically in the middle molecular layer of the dentate gyrus (DG) of young, middle aged and old Fischer 344 x Brown Norway rats fed ad libitum (AL) or a CR diet from 4 months of age. The results indicate that synapses are maintained across lifespan in both AL and CR rats. In light of this stability, we addressed whether aging and CR influence neurotransmitter receptor levels by measuring subunits of NMDA (NR1, NR2A and NR2B) and AMPA (GluR1, GluR2) receptors in the DG of a second cohort of AL and CR rats across lifespan. The results reveal that the NR1 and GluR1 subunits decline with age in AL, but not CR rats. The absence of an aging-related decline in these subunits in CR rats, however, does not arise from increased levels in old CR rats. Instead, it is due to subunit decreases in young CR rats to levels that are sustained in CR rats throughout lifespan, but that are reached in AL rats only in old age.

Age-related synapse loss in hippocampal CA3 is not reversed by caloric restriction

Caloric restriction (CR) is a reduction of total caloric intake without a decrease in micronutrients or a disproportionate reduction of any one dietary component. While CR attenuates age-related cognitive deficits in tasks of hippocampal-dependent memory, the cellular mechanisms by which CR improves this cognitive decline are poorly understood. Previously, we have reported age-related decreases in key synaptic proteins in the CA3 region of the hippocampus that are stabilized by lifelong CR. In the present study, we examined possible age-related changes in the functional microcircuitry of the synapses in the stratum lacunosum-molecular (SL-M) of the CA3 region of the hippocampus, and whether lifelong CR might prevent these age-related alterations. We used serial electron microscopy to reconstruct and classify SL-M synapses and their postsynaptic spines. We analyzed synapse number and size as well as spine surface area and volume in young (10 months) and old (29 months) ad libitum fed rats and in old rats that were calorically restricted from 4 months of age. We limited our analysis to SL-M because previous work demonstrated age-related decreases in synaptophysin confined to this specific layer and region of the hippocampus. The results revealed an age-related decrease in macular axo-spinous synapses that was not reversed by CR that occurred in the absence of changes in the size of synapses or spines. Thus, the benefits of CR for CA3 function and synaptic plasticity may involve other biological effects including the stabilization of synaptic proteins levels in the face of age-related synapse loss.

Radiation Protection for the Fluoroscopy Operator and Staff.

OBJECTIVE The purposes of this article are to review available data regarding the range of protection devices and garments with a focus on eye protection and to summarize techniques for reducing scatter radiation exposure. CONCLUSION Fluoroscopy operators and staff can greatly reduce their radiation exposure by wearing properly fitted protective garments, positioning protective devices to block scatter radiation, and adhering to good radiation practices. By understanding the essentials of radiation physics, protective equipment, and the features of each imaging system, operators and staff can capitalize on opportunities for radiation protection while minimizing ergonomic strain. Practicing and promoting a culture of radiation safety can help fluoroscopy operators and staff enjoy long, productive careers helping patients.

Locoregional therapies for hepatocellular carcinoma and the new LI-RADS treatment response algorithm

Radiologists play a central role in the assessment of patient response to locoregional therapies for hepatocellular carcinoma (HCC). The identification of viable tumor following treatment guides further management and potentially affects transplantation eligibility. Liver Imaging Reporting and Data Systems (LI-RADS) first introduced the concept of LR-treated in 2014, and a new treatment response algorithm is included in the 2017 update to assist radiologists in image interpretation of HCC after locoregional therapy. In addition to offering imaging criteria for viable and nonviable HCC, new concepts of nonevaluable tumors as well as tumors with equivocal viability are introduced. Existing guidelines provided by response evaluation criteria in solid tumors (RECIST) and modified RECIST address patient-level assessments and are routinely used in clinical trials but do not address the variable appearances following different locoregional therapies. The new LI-RADS treatment response algorithm addresses this gap and offers a comprehensive approach to assess treatment response for individual lesions after a variety of locoregional therapies, using either contrast-enhanced CT or MRI.

Web-Based Tools and Mobile Applications To Mitigate Burnout, Depression, and Suicidality Among Healthcare Students and Professionals: a Systematic Review

ObjectiveBeing a healthcare professional can be a uniquely rewarding calling. However, the demands of training and practice can lead to chronic distress and serious psychological, interpersonal, and personal health burdens. Although higher burnout, depression, and suicide rates have been reported in healthcare professionals, only a minority receive treatment. Concerns regarding confidentiality, stigma, potential career implications, and cost and time constraints are cited as key barriers. Web-based and mobile applications have been shown to mitigate stress, burnout, depression, and suicidal ideation among several populations and may circumvent these barriers. Here, we reviewed published data on such resources and selected a small sample that readily can be used by healthcare providers.MethodsWe searched PubMed for articles evaluating stress, burnout, depression, and suicide prevention or intervention for healthcare students or providers and identified five categories of programs with significant effectiveness: Cognitive Behavioral Therapy (online), meditation, mindfulness, breathing, and relaxation techniques. Using these categories, we searched for Web-based (through Google and beacon.anu.edu.au—a wellness resource website) and mobile applications (Apple and mobile.va.gov/appstore) for stress, burnout, depression, and suicide prevention and identified 36 resources to further evaluate based on relevance, applicability to healthcare providers (confidentiality, convenience, and cost), and the strength of findings supporting their effectiveness.ResultsWe selected seven resources under five general categories designed to foster wellness and reduce burnout, depression, and suicide risk among healthcare workers: breathing (Breath2Relax), meditation (Headspace, guided meditation audios), Web-based Cognitive Behavioral Therapy (MoodGYM, Stress Gym), and suicide prevention apps (Stay Alive, Virtual Hope Box).ConclusionsThis list serves as a starting point to enhance coping with stressors as a healthcare student or professional in order to help mitigate burnout, depression, and suicidality. The next steps include adapting digital health strategies to specifically fit the needs of healthcare providers, with the ultimate goal of facilitating in-person care when warranted.

Intravascular Ultrasound in the Creation of Transhepatic Portosystemic Shunts Reduces Needle Passes, Radiation Dose, and Procedure Time: A Retrospective Study of a Single-Institution Experience

PURPOSE To assess whether intravascular ultrasound (US) guidance impacts number of needle passes, contrast usage, radiation dose, and procedure time during creation of transjugular intrahepatic portosystemic shunts (TIPS). MATERIALS AND METHODS Intravascular US-guided creation of TIPS in 40 patients was retrospectively compared with conventional TIPS in 49 patients between February 2010 and November 2015 at a single tertiary care institution. Patient sex and age, etiology of liver disease (hepatitis C virus, alcohol abuse, nonalcoholic steatohepatitis), severity of liver disease (mean Model for End-Stage Liver Disease score), and indications for TIPS (variceal bleeding, refractory ascites, refractory hydrothorax) in conventional and intravascular US-guided cases were recorded. RESULTS The two groups were well matched by sex, age, etiology of liver disease, Child-Pugh class, Model for End-Stage Liver Disease scores, and indication for TIPS (P range = .19-.94). Fewer intrahepatic needle passes were required in intravascular US-guided TIPS creation compared with conventional TIPS (2 passes vs 6 passes, P < .01). Less iodinated contrast material was used in intravascular US cases (57 mL vs 140 mL, P < .01). Radiation exposure, as measured by cumulative dose, dose area product, and fluoroscopy time, was reduced with intravascular US (174 mGy vs 981 mGy, P < .01; 3,793 μGy * m(2) vs 21,414 μGy * m(2), P < .01; 19 min vs 34 min, P < .01). Procedure time was shortened with intravascular US (86 min vs 125 min, P < .01). CONCLUSIONS Intravascular US guidance resulted in fewer intrahepatic needle passes, decreased contrast medium usage, decreased radiation dosage, and shortened procedure time in TIPS creation.