ATP-binding cassette (ABC) transporters are important selective elements of the blood–brain barrier. They line the luminal plasma membrane of the brain capillary endothelium, facing the vascular ...space, and both protect the central nervous system from entry of neurotoxicants and limit the access of therapeutic drugs to the brain parenchyma. Recent studies highlight the multiple signaling pathways through which the expression and activity of P-glycoprotein and other ABC transporters are modulated in response to xenobiotics, stress and disease. The results show that increased transporter expression occurs in response to signals that activate specific transcription factors, including pregnane-X receptor, constitutive androstane receptor, nuclear factor-κB and activator protein-1, and that reduced transporter activity occurs rapidly and reversibly in response to signaling through Src kinase, protein kinase C and estrogen receptors. A detailed understanding of such regulation can provide the basis for improved neuroprotection and enhanced therapeutic drug delivery to the brain.
The Alzheimer's Association's Research Roundtable met in November 2017 to explore the new National Institute on Aging and the Alzheimer's Association Research Framework for Alzheimer's disease. The ...meeting allowed experts in the field from academia, industry, and government to provide perspectives on the new National Institute on Aging and the Alzheimer's Association Research Framework. This review will summarize the “A, T, N System” (Amyloid, Tau, and Neurodegeneration) using biomarkers and how this may be applied to clinical research and drug development. In addition, challenges and barriers to the potential adoption of this new framework will be discussed. Finally, future directions for research will be proposed.
Abstract The strength of the blood-brain barrier (BBB) in providing protection to the central nervous system from exposure to circulating chemicals is maintained by tight junctions between ...endothelial cells and by a broad range of transporter proteins that regulate exchange between CNS and blood. The most important transporters that restrict the permeability of large number of toxins as well as therapeutic agents are the ABC transporters. Among them, P-gp, BCRP, MRP1 and MRP2 are the utmost studied. These efflux transporters are neuroprotective, limiting the brain entry of neurotoxins; however, they could also restrict the entry of many therapeutics and contribute to CNS pharmacoresistance. Characterization of several regulatory pathways that govern expression and activity of ABC efflux transporters in the endothelium of brain capillaries have led to an emerging consensus that these processes are complex and contain several cellular and molecular elements. Alterations in ABC efflux transporters expression and/or activity occur in several neurological diseases. Here, we review the signaling pathways that regulate expression and transport activity of P-gp, BCRP, MRP1 and MRP2 as well as how their expression/activity changes in neurological diseases. This article is part of a Special Issue entitled SI: Neuroprotection.
Limitations of the paclitaxel-doxorubicin-cisplatin (TAP) regimen in the treatment of endometrial cancer include tolerability and cumbersome scheduling. The Gynecologic Oncology Group studied ...carboplatin plus paclitaxel (TC) as a noninferior alternative to TAP.
GOG0209 was a phase III, randomized, noninferiority, open-label trial. Inclusion criteria were stage III, stage IV, and recurrent endometrial cancers; performance status 0-2; and adequate renal, hepatic, and marrow function. Prior radiotherapy and/or hormonal therapy were permitted, but chemotherapy, including radiosensitization, was not. Patients were treated with doxorubicin 45 mg/m
and cisplatin 50 mg/m
(day 1), followed by paclitaxel 160 mg/m
(day 2) with granulocyte colony-stimulating factor or paclitaxel 175 mg/m
and carboplatin area under the curve 6 (day 1) every 21 days for seven cycles. The primary endpoint was overall survival (OS; modified intention to treat). Progression-free survival (PFS), health-related quality of life (HRQoL), and toxicity were secondary endpoints.
From 2003 to 2009, 1,381 women were enrolled. Noninferiority of TC to TAP was concluded for OS (median, 37
41 months, respectively; hazard ratio HR, 1.002; 90% CI, 0.9 to 1.12), and PFS (median, 13
14 months; HR, 1.032; 90% CI, 0.93 to 1.15). Neutropenic fever was reported in 7% of patients receiving TAP and 6% of those receiving TC. Grade > 2 sensory neuropathy was recorded in 26% of patients receiving TAP and 20% receiving TC (
= .40). More grade ≥ 3 thrombocytopenia (23%
12%), vomiting (7%
4%), diarrhea (6%
2%), and metabolic (14%
8%) toxicities were reported with TAP. Neutropenia (52%
80%) was more common with TC. Small HRQoL differences favored TC.
With demonstrated noninferiority to TAP, TC is the global first-line standard for advanced endometrial cancer.
The brain capillary endothelial cells that constitute the blood-brain barrier express multiple ABC transport proteins on the luminal, blood-facing, plasma membrane. These transporters function as ...ATP-driven efflux pumps for xenobiotics and endogenous metabolites. High expression of these ABC transporters at the barrier is a major obstacle to the delivery of therapeutics, including chemotherapeutics, to the CNS. Here, I review the signals that alter ABC transporter expression and transport function with an emphasis on P-glycoprotein, Mrp2, and breast cancer resistance protein (BCRP), the efflux transporters for which we have the most detailed picture of regulation. Recent work shows that transporter protein expression can be upregulated in response to inflammatory and oxidative stress, therapeutic drugs, diet, and persistent environmental pollutants; as a consequence, drug delivery to the brain is reduced (potentially bad and ugly). In contrast, basal transport activity of P-glycoprotein and BCRP can be reduced through complex signaling pathways that involve events in and on the brain capillary endothelial cells. Targeting these signaling events provides opportunities to rapidly and reversibly increase brain accumulation of drugs that are substrates for the transporters (potentially good). The clinical usefulness of targeting signaling to reduce efflux transporter activity and improve drug delivery to the CNS remains to be established.
Pancreatic ductal adenocarcinoma is an aggressive malignancy with a high mortality rate. Proper determination of the extent of disease on imaging studies at the time of staging is one of the most ...important steps in optimal patient management. Given the variability in expertise and definition of disease extent among different practitioners as well as frequent lack of complete reporting of pertinent imaging findings at radiologic examinations, adoption of a standardized template for radiology reporting, using universally accepted and agreed on terminology for solid pancreatic neoplasms, is needed. A consensus statement describing a standardized reporting template authored by a multi-institutional group of experts in pancreatic ductal adenocarcinoma that included radiologists, gastroenterologists, and hepatopancreatobiliary surgeons was developed under the joint sponsorship of the Society of Abdominal Radiologists and the American Pancreatic Association. Adoption of this standardized imaging reporting template should improve the decision-making process for the management of patients with pancreatic ductal adenocarcinoma by providing a complete, pertinent, and accurate reporting of disease staging to optimize treatment recommendations that can be offered to the patient. Standardization can also help to facilitate research and clinical trial design by using appropriate and consistent staging by means of resectability status, thus allowing for comparison of results among different institutions.
Knowledge regarding genetic diversity and population structure of breeding materials is essential for crop improvement. The Texas A&M University Potato Breeding Program has a collection of advanced ...clones selected and maintained in-vitro over a 40-year period. Little is known about its genetic makeup and usefulness for the current breeding program. In this study, 214 potato clones were genotyped with the Infinium Illumina 22 K V3 Potato Array. After filtering, a total of 10,106 single nucleotide polymorphic (SNP) markers were used for analysis. Heterozygosity varied by SNP, with an overall average of 0.59. Three groups of tetraploid clones primarily based on potato market classes, were detected using STRUCTURE software and confirmed by discriminant analysis of principal components. The highest coefficient of differentiation observed between the groups was 0.14. Signatures of selection were uncovered in genes controlling potato flesh and skin color, length of plant cycle and tuberization, and carbohydrate metabolism. A core set of 43 clones was obtained using Core Hunter 3 to develop a sub-collection that retains similar genetic diversity as the whole population, minimize redundancies, and facilitates long-term conservation of genetic resources. The comprehensive molecular characterization of our breeding clone bank collection contributes to understanding the genetic diversity of existing potato resources. This analysis could be applied to other breeding programs and assist in the selection of parents, fingerprinting, protection, and management of the breeding collections.
Stage III or IVA endometrial cancer carries a significant risk of systemic and locoregional recurrence.
In this randomized phase 3 trial, we tested whether 6 months of platinum-based chemotherapy ...plus radiation therapy (chemoradiotherapy) is associated with longer relapse-free survival (primary end point) than six cycles of combination chemotherapy alone in patients with stage III or IVA endometrial carcinoma. Secondary end points included overall survival, acute and chronic toxic effects, and quality of life.
Of the 813 patients enrolled, 736 were eligible and were included in the analysis of relapse-free survival; of those patients, 707 received the randomly assigned intervention (346 received chemoradiotherapy and 361 received chemotherapy only). The median follow-up period was 47 months. At 60 months, the Kaplan-Meier estimate of the percentage of patients alive and relapse-free was 59% (95% confidence interval CI, 53 to 65) in the chemoradiotherapy group and 58% (95% CI, 53 to 64) in the chemotherapy-only group (hazard ratio, 0.90; 90% CI, 0.74 to 1.10). Chemoradiotherapy was associated with a lower 5-year incidence of vaginal recurrence (2% vs. 7%; hazard ratio, 0.36; 95% CI, 0.16 to 0.82) and pelvic and paraaortic lymph-node recurrence (11% vs. 20%; hazard ratio, 0.43; 95% CI, 0.28 to 0.66) than chemotherapy alone, but distant recurrence was more common in association with chemoradiotherapy (27% vs. 21%; hazard ratio, 1.36; 95% CI, 1.00 to 1.86). Grade 3, 4, or 5 adverse events were reported in 202 patients (58%) in the chemoradiotherapy group and 227 patients (63%) in the chemotherapy-only group.
Chemotherapy plus radiation was not associated with longer relapse-free survival than chemotherapy alone in patients with stage III or IVA endometrial carcinoma. (Funded by the National Cancer Institute; ClinicalTrials.gov number, NCT00942357.).
The purpose of this study was to investigate issues of equity in access, uptake, and outcomes of high school music education in the context of an individual state, Maryland. I explored equity through ...four angles: (a) representation among music students and teachers, (b) factors associated with access to music courses, (c) student and school characteristics associated with music enrollment, and (d) postsecondary enrollment outcomes of students who did and did not enroll in music. Sample members included all students enrolled in a public high school in Maryland belonging to the 2015 to 2016 ninth-grade cohort (N = 55,500) and public high school teachers (N = 17,250) during the 2015 to 2016 school year. Approximately 22% of all students were enrolled in a music course their ninth-grade year, and there were substantive differences in demographic representation in band, chorus, orchestra, piano, and guitar classes compared to the student body. Logistic regression results showed that school size was the most salient predictor of access to a music course. Multilevel modeling revealed student-, school-, and teacher-level characteristics were all associated with student enrollment in an ensemble music course. Finally, students who enrolled in music courses did not suffer an opportunity cost regarding college enrollment.
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