Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 53
Filter
1.
J Adolesc Health ; 73(2): 387-389, 2023 08.
Article in English | MEDLINE | ID: mdl-37125986

ABSTRACT

PURPOSE: To assess the rate of mental health diagnoses and selective serotonin reuptake inhibitor (SSRI) prescribing before and during the Coronavirus Disease 2019 pandemic. METHODS: We conducted a cross-sectional study at an ambulatory pediatric clinic. A prepandemic (June 2018 to June 2019) and intrapandemic (June 2020 to June 2021) cohort were reviewed. The rate of mental health visits and new SSRI prescriptions were compared. Chi-squared analyses demonstrated a variance of statistical significance. RESULTS: From 15,414 encounters (9,791 prepandemic and 5,623 intrapandemic), 397 mental health encounters were identified. 231 (4.1%) encounters occurred during the pandemic (vs. 1.7% prepandemic) and 63 (27.3%) SSRIs were prescribed (vs. 5.4% prepandemic). Mental health encounters (prevalence ratio 2.42, 95% confidence interval, 1.99-2.95, p < .001) and SSRI prescriptions (prevalence ratio 5.03, 95% confidence interval, 2.58-9.82, p < .001) were higher during the pandemic. DISCUSSION: Our findings demonstrate increased rates of SSRI prescribing and mental health diagnoses during the Coronavirus Disease 2019 pandemic, suggesting an increased incidence of these conditions. Clinicians should be prepared to manage and screen for mental health conditions.


Subject(s)
COVID-19 , Selective Serotonin Reuptake Inhibitors , Humans , Child , Selective Serotonin Reuptake Inhibitors/therapeutic use , Pandemics , Mental Health , Cross-Sectional Studies
2.
J Law Med Ethics ; 48(2): 249-258, 2020 06.
Article in English | MEDLINE | ID: mdl-32631181

ABSTRACT

Overdose deaths involving prescription opioids killed more than 17,000 Americans in 2017, marking a five-fold increase since 1999. High prescribing rates of opioid analgesics have been a substantial contributor to prescription opioid misuse, dependence, overdose and heroin use. There was recognition approximately ten years ago that opioid prescribing patterns were contributing to this startling increase in negative opioid-related outcomes, and federal actions, including Medicare reimbursement reform and regulatory actions, were initiated to restrict opioid prescribing. The current manuscript is a description of those actions, the effect of those actions on opioid prescribing and related patient outcomes. We also describe our proposal of methods of expanding these efforts as an important piece to further reduce opioid-related misuse, dependence, and overdose death.


Subject(s)
Analgesics, Opioid/therapeutic use , Opiate Overdose/mortality , Practice Patterns, Physicians'/legislation & jurisprudence , Practice Patterns, Physicians'/statistics & numerical data , Practice Patterns, Physicians'/trends , Prescription Drug Misuse/trends , Federal Government , Government Regulation , Humans , State Government , United States/epidemiology
3.
JMIR Mhealth Uhealth ; 6(7): e10414, 2018 Jul 30.
Article in English | MEDLINE | ID: mdl-30061091

ABSTRACT

The rapid growth of mobile health (mHealth) apps has resulted in confusion among health care providers and the public about which products rely on evidence-based medicine. Only a small subset of mHealth apps are regulated by the US Food and Drug Administration. The system similar to that used to accredit and certify laboratory testing under the Clinical Laboratory Improvement Amendment offers a potential model for ensuring basic standards of quality and safety for mHealth apps. With these products expanding into the realm of diagnosis and treatment, physicians and consumers are in a strong position to demand oversight that delivers safe and high-quality mHealth apps.

4.
J Clin Transl Res ; 4(1): 56-69, 2018 May 28.
Article in English | MEDLINE | ID: mdl-30873495

ABSTRACT

BACKGROUND: Trials that involve human participants call for experiments or observations that are performed in a clinical research setting. Currently, there are over 16,000 clinical trials open in the United States. Despite continuing efforts to include "special populations" in clinical trials, there are gaps in participation for people who are either minors or elderly adults, are from historically under-represented minorities, or live in rural communities. The inclusion of these special populations in clinical trials research is essential for conclusions that benefit all populations. Data suggest that study partic-ipation rates for special populations have fallen to levels that could endanger the successful performance of some types of research. This is particularly concerning in the 21st century, where demographic trends in the United States continue to shift towards an older and Hispanic population with fewer rural dwellers. Trends in New Mexico and other minority-majority states mirror many of these shifts. RELEVANCE FOR PATIENTS: In this review, we highlight improvement strategies for enhanced clinical trial participation by members of special populations. Key drivers for disparate clinical trials participation and outcomes often include differences in genetics, physiology, and perceptions of mistrust towards researchers. To overcome these barriers, we focus on best practices in recruitment strategies from the perspectives of the participants, the researchers and the institutions that support clinical trials.

6.
J Am Board Fam Med ; 30(1): 94-99, 2017 01 02.
Article in English | MEDLINE | ID: mdl-28062823

ABSTRACT

Health Extension Regional Officers (HEROs) through the University of New Mexico Health Sciences Center (UNMHSC) help to facilitate university-community engagement throughout New Mexico. HEROs, based in communities across the state, link priority community health needs with university resources in education, service, and research. Researchers' studies are usually aligned with federal funding priorities rather than with health priorities expressed by communities. To help overcome this misalignment, the UNM Clinical and Translational Science Center (CTSC) provides partial funding for HEROs to bridge the divide between research priorities of UNMHSC and health priorities of the state's communities. A bidirectional partnership between HEROs and CTSC researchers was established, which led to: 1) increased community engaged studies through the CTSC, 2) the HERO model itself as a subject of research, 3) a HERO-driven increase in local capacity in scholarship and grant writing, and 4) development of training modules for investigators and community stakeholders on community-engaged research. As a result, 5 grants were submitted, 4 of which were funded, totaling $7,409,002.00, and 3 research articles were published. Health extension can serve as a university-funded, community-based bridge between community health needs and Clinical and Translational Science Award (CTSA) research capacity, opening avenues for translational research.


Subject(s)
Biomedical Research/economics , Community-Based Participatory Research/economics , Community-Institutional Relations/economics , Health Priorities/economics , Health Services Needs and Demand , Research Personnel/economics , Awards and Prizes , Biomedical Research/methods , Financial Management/methods , Humans , New Mexico , Universities/economics
7.
Mol Cancer Ther ; 15(12): 2853-2862, 2016 12.
Article in English | MEDLINE | ID: mdl-27671528

ABSTRACT

Chemotherapeutic resistance remains a challenge in the treatment of ovarian carcinoma, especially in recurrent disease. Despite the fact that most patients with newly diagnosed tumors attain complete remission following cytoreductive surgery and chemotherapy, ovarian carcinoma has a recurrence rate that exceeds 75%. The ATP-binding cassette family G member 2 (ABCG2) efflux protein has been described as one mechanism that confers multiple-drug resistance to solid tumors and contributes to topotecan resistance in ovarian carcinoma. In fact, one clinical trial demonstrated ABCG2 expression in all patients with primary or recurrent ovarian carcinoma. On the basis of our previous work, we hypothesized that three compounds (CID44640177, CID1434724, and CID46245505), which represent a new piperazine-substituted pyrazolo[1,5]pyrimidine substructure class of ABCG2-specific antagonists, would restore chemosensitivity to drug-resistant ovarian cancer in vitro and in vivo To address the treatment difficulties associated with chemotherapeutic resistance in ovarian cancer, we combined each compound (CID44640177, CID1434724, and CID46245505) with topotecan and administered the mixture to chemoresistant Igrov1/T8 ovarian cancer cells in vitro and Igrov1/T8 xenografts in CB-17 SCID mice. We found that only nanomolar concentrations of each ABCG2 inhibitor in combination with topotecan were required to restore chemosensitivity to Igrov1/T8 cells in vitro In vivo, substantial tumor reduction was achieved with each compound in 4 days, with CID1434724 causing the largest reduction in excess of 60%. No signs of secondary toxic effects were observed with the ABCG2 antagonists. These novel compounds should be viewed as promising drug candidates to reverse ABCG2-mediated chemoresistance. Mol Cancer Ther; 15(12); 2853-62. ©2016 AACR.


Subject(s)
ATP Binding Cassette Transporter, Subfamily G, Member 2/antagonists & inhibitors , Antineoplastic Agents/pharmacology , Carcinoma/metabolism , Drug Resistance, Neoplasm , Ovarian Neoplasms/metabolism , Topotecan/pharmacology , ATP Binding Cassette Transporter, Subfamily G, Member 2/genetics , Animals , Antineoplastic Agents/administration & dosage , Carcinoma/drug therapy , Carcinoma/pathology , Cell Line, Tumor , Cell Survival/drug effects , Disease Models, Animal , Dose-Response Relationship, Drug , Drug Resistance, Neoplasm/genetics , Female , Humans , Mice , Ovarian Neoplasms/drug therapy , Ovarian Neoplasms/genetics , Ovarian Neoplasms/pathology , Topotecan/administration & dosage , Tumor Burden/drug effects , Xenograft Model Antitumor Assays
8.
Sensors (Basel) ; 15(4): 8605-14, 2015 Apr 14.
Article in English | MEDLINE | ID: mdl-25875186

ABSTRACT

Surface acoustic wave (SAW) sensors can rapidly detect Ebola antigens at the point-of-care without the need for added reagents, sample processing, or specialized personnel. This preliminary study demonstrates SAW biosensor detection of the Ebola virus in a concentration-dependent manner. The detection limit with this methodology is below the average level of viremia detected on the first day of symptoms by PCR. We observe a log-linear sensor response for highly fragmented Ebola viral particles, with a detection limit corresponding to 1.9 × 104 PFU/mL prior to virus inactivation. We predict greatly improved sensitivity for intact, infectious Ebola virus. This point-of-care methodology has the potential to detect Ebola viremia prior to symptom onset, greatly enabling infection control and rapid treatment. This biosensor platform is powered by disposable AA batteries and can be rapidly adapted to detect other emerging diseases in austere conditions.


Subject(s)
Biosensing Techniques/methods , Ebolavirus/isolation & purification , Humans
9.
Am J Prev Med ; 48(1): 108-15, 2015 Jan.
Article in English | MEDLINE | ID: mdl-25441236

ABSTRACT

The University of New Mexico Health Sciences Center (UNMHSC) adopted a new Vision to work with community partners to help New Mexico make more progress in health and health equity than any other state by 2020. UNMHSC recognized it would be more successful in meeting communities' health priorities if it better aligned its own educational, research, and clinical missions with their needs. National measures that compare states on the basis of health determinants and outcomes were adopted in 2013 as part of Vision 2020 target measures for gauging progress toward improved health and health care in New Mexico. The Vision focused the institution's resources on strengthening community capacity and responding to community priorities via pipeline education, workforce development programs, community-driven and community-focused research, and community-based clinical service innovations, such as telehealth and "health extension." Initiatives with the greatest impact often cut across institutional silos in colleges, departments, and programs, yielding measurable community health benefits. Community leaders also facilitated collaboration by enlisting University of New Mexico educational and clinical resources to better respond to their local priorities. Early progress in New Mexico's health outcomes measures and state health ranking is a promising sign of movement toward Vision 2020.


Subject(s)
Community-Institutional Relations , Health Priorities , Healthy People Programs/organization & administration , Social Determinants of Health , Capacity Building/methods , Capacity Building/organization & administration , Capacity Building/standards , Healthy People Programs/methods , Healthy People Programs/standards , Humans , New Mexico , Organizational Case Studies , Universities
10.
Phys Med Biol ; 59(13): 3319-35, 2014 Jul 07.
Article in English | MEDLINE | ID: mdl-24874577

ABSTRACT

As new magnetic nanoparticle-based technologies are developed and new target cells are identified, there is a critical need to understand the features important for magnetic isolation of specific cells in fluids, an increasingly important tool in disease research and diagnosis. To investigate magnetic cell collection, cell-sized spherical microparticles, coated with superparamagnetic nanoparticles, were suspended in (1) glycerine-water solutions, chosen to approximate the range of viscosities of bone marrow, and (2) water in which 3, 5, 10 and 100% of the total suspended microspheres are coated with magnetic nanoparticles, to model collection of rare magnetic nanoparticle-coated cells from a mixture of cells in a fluid. The magnetic microspheres were collected on a magnetic needle, and we demonstrate that the collection efficiency versus time can be modeled using a simple, heuristically-derived function, with three physically-significant parameters. The function enables experimentally-obtained collection efficiencies to be scaled to extract the effective drag of the suspending medium. The results of this analysis demonstrate that the effective drag scales linearly with fluid viscosity, as expected. Surprisingly, increasing the number of non-magnetic microspheres in the suspending fluid results increases the collection of magnetic microspheres, corresponding to a decrease in the effective drag of the medium.


Subject(s)
Cell Separation/instrumentation , Magnetic Phenomena , Models, Biological , Needles , Microspheres , Nanoparticles/chemistry , Polystyrenes/chemistry , Time Factors
11.
Health (Irvine Calif) ; 5(5A)2013 May.
Article in English | MEDLINE | ID: mdl-24224072

ABSTRACT

PURPOSE: In acute lymphoblastic leukemia (ALL), multidrug resistance is often mediated by ATPase Binding Cassette (ABC) proteins, which principally involve ABCB1 (multidrug resistance 1, MDR1) and ABCC1 (multidrug resistance protein 1, MRP1). However, direct comparisons between the differential effects of ABCB1 and ABCC1 have been difficult, since identical cell lines with differential expression of these transporters have not been developed. EXPERIMENTAL DESIGN: In this study, we developed and compared the biological profiles of Jurkat cell lines that selectively over-expressed ABCB1 and ABCC1. Vincristine (VCR) plays an important role in the treatment of T-lineage ALL (T-ALL), and is often the first drug given to newly-diagnosed patients. Because of its importance in treatment, we provided escalating, sub-lethal doses of VCR to Jurkat cells, and extended our observations to expression profiling of newly diagnosed patients with T-ALL. RESULTS: We found that VCR-resistant cells over-expressed ABCC1 nearly 30-fold. The calcein AM assay confirmed that VCR-resistant cells actively extruded VCR, and that ABCC1-mediated drug resistance conferred a different spectrum of multidrug resistance than other T-ALL induction agents. siRNA experiments that blocked ABCC1 export confirmed that VCR resistance could be reversed in vitro. Analyses of T-lymphoblasts obtained from 92 newly diagnosed T-ALL patients treated on Children's Oncology Group Phase III studies 8704/9404 showed that induction failure could be explained in all but one case by the over-expression of ABCB1 or ABCC1. CONCLUSIONS: Taken together, these results suggest that over-expression of ABC transporters plays a contributing role in mediating treatment failure in T-ALL, and underscore the need to employ alternate treatment approaches in patients for whom induction failed or for those with relapsed disease.

12.
Anal Biochem ; 437(1): 77-87, 2013 Jun 01.
Article in English | MEDLINE | ID: mdl-23470221

ABSTRACT

ATP binding cassette (ABC) transmembrane efflux pumps such as P-glycoprotein (ABCB1), multidrug resistance protein 1 (ABCC1), and breast cancer resistance protein (ABCG2) play an important role in anticancer drug resistance. A large number of structurally and functionally diverse compounds act as substrates or modulators of these pumps. In vitro assessment of the affinity of drug candidates for multidrug resistance proteins is central to predict in vivo pharmacokinetics and drug-drug interactions. The objective of this study was to identify and characterize new substrates for these transporters. As part of a collaborative project with Life Technologies, 102 fluorescent probes were investigated in a flow cytometric screen of ABC transporters. The primary screen compared substrate efflux activity in parental cell lines with their corresponding highly expressing resistant counterparts. The fluorescent compound library included a range of excitation/emission profiles and required dual laser excitation as well as multiple fluorescence detection channels. A total of 31 substrates with active efflux in one or more pumps and practical fluorescence response ranges were identified and tested for interaction with eight known inhibitors. This screening approach provides an efficient tool for identification and characterization of new fluorescent substrates for ABCB1, ABCC1, and ABCG2.


Subject(s)
ATP-Binding Cassette Transporters/antagonists & inhibitors , ATP-Binding Cassette Transporters/metabolism , Flow Cytometry/methods , Fluorescent Dyes/metabolism , ATP Binding Cassette Transporter, Subfamily B , ATP Binding Cassette Transporter, Subfamily B, Member 1/antagonists & inhibitors , ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics , ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism , ATP Binding Cassette Transporter, Subfamily G, Member 2 , ATP-Binding Cassette Transporters/genetics , Cell Line , Humans , Multidrug Resistance-Associated Proteins/antagonists & inhibitors , Multidrug Resistance-Associated Proteins/genetics , Multidrug Resistance-Associated Proteins/metabolism , Neoplasm Proteins/antagonists & inhibitors , Neoplasm Proteins/genetics , Neoplasm Proteins/metabolism , Protein Binding
13.
J Clin Microbiol ; 51(6): 1685-91, 2013 Jun.
Article in English | MEDLINE | ID: mdl-23515541

ABSTRACT

Disasters can create situations in which blood donations can save lives. However, in emergency situations and when resources are depleted, on-site blood donations require the rapid and accurate detection of blood-borne pathogens, including human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2). Techniques such as PCR and antibody capture by an enzyme-linked immunosorbent assay (ELISA) for HIV-1 and HIV-2 are precise but time-consuming and require sophisticated equipment that is not compatible with emergency point-of-care requirements. We describe here a prototype biosensor based on piezoelectric materials functionalized with specific antibodies against HIV-1 and HIV-2. We show the rapid and accurate detection of HIV-1 and HIV-2 in both simple and complex solutions, including human serum, and in the presence of a cross-confounding virus. We report detection limits of 12 50% tissue culture infective doses (TCID50s) for HIV-1 and 87 TCID50s for HIV-2. The accuracy, precision of measurements, and operation of the prototype biosensor compared favorably to those for nucleic acid amplification. We conclude that the biosensor has significant promise as a successful point-of-care diagnostic device for use in emergency field applications requiring rapid and reliable testing for blood-borne pathogens.


Subject(s)
Biosensing Techniques/methods , Clinical Laboratory Techniques/methods , HIV Infections/diagnosis , HIV-1/isolation & purification , HIV-2/isolation & purification , Virology/methods , Biosensing Techniques/instrumentation , Clinical Laboratory Techniques/instrumentation , Humans , Point-of-Care Systems , Sensitivity and Specificity , Virology/instrumentation
14.
Leuk Lymphoma ; 54(8): 1762-8, 2013 Aug.
Article in English | MEDLINE | ID: mdl-23311322

ABSTRACT

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive leukemia with high relapse rates compared to B-lineage ALL. We previously showed that HMGA1a transgenic mice develop aggressive T-ALL, indicating that HMGA1 causes leukemic transformation in vivo. HMGA1 is also highly expressed in embryonic stem cells, hematopoietic stem cells and diverse, refractory human cancers. Disruption of the CDKN2A tumor suppressor locus occurs in most cases of T-ALL and is thought to contribute to leukemic transformation. To determine whether loss of function of CDKN2A cooperates with HMGA1 in T-ALL, we crossed HMGA1a transgenics onto a Cdkn2a null background. We discovered that T-ALL is markedly accelerated in HMGA1a transgenic Cdkn2a null mice. In addition, these mice recapitulate salient clinical and pathologic features of human T-ALL. HMGA1 is also highly overexpressed in human T-ALL. These findings suggest that HMGA1 plays a causative role in T-ALL and could represent a rational therapeutic target.


Subject(s)
Cell Transformation, Neoplastic/genetics , Cyclin-Dependent Kinase Inhibitor p16/genetics , Epistasis, Genetic , Gene Silencing , HMGA1a Protein/genetics , Leukemia, T-Cell/genetics , Animals , Disease Models, Animal , Female , Gene Expression , Genetic Loci , Humans , Immunophenotyping , Leukemia, T-Cell/metabolism , Male , Mice , Mice, Knockout
15.
J Biomol Screen ; 18(1): 26-38, 2013 Jan.
Article in English | MEDLINE | ID: mdl-22923785

ABSTRACT

Chemotherapeutics tumor resistance is a principal reason for treatment failure, and clinical and experimental data indicate that multidrug transporters such as ATP-binding cassette (ABC) B1 and ABCG2 play a leading role by preventing cytotoxic intracellular drug concentrations. Functional efflux inhibition of existing chemotherapeutics by these pumps continues to present a promising approach for treatment. A contributing factor to the failure of existing inhibitors in clinical applications is limited understanding of specific substrate/inhibitor/pump interactions. We have identified selective efflux inhibitors by profiling multiple ABC transporters against a library of small molecules to find molecular probes to further explore such interactions. In our primary screening protocol using JC-1 as a dual-pump fluorescent reporter substrate, we identified a piperazine-substituted pyrazolo[1,5-a]pyrimidine substructure with promise for selective efflux inhibition. As a result of a focused structure-activity relationship (SAR)-driven chemistry effort, we describe compound 1 (CID44640177), an efflux inhibitor with selectivity toward ABCG2 over ABCB1. Compound 1 is also shown to potentiate the activity of mitoxantrone in vitro as well as preliminarily in vivo in an ABCG2-overexpressing tumor model. At least two analogues significantly reduce tumor size in combination with the chemotherapeutic topotecan. To our knowledge, low nanomolar chemoreversal activity coupled with direct evidence of efflux inhibition for ABCG2 is unprecedented.


Subject(s)
ATP-Binding Cassette Transporters/antagonists & inhibitors , Antineoplastic Agents/pharmacology , Neoplasm Proteins/antagonists & inhibitors , Pyrazoles/pharmacology , Pyrimidines/pharmacology , ATP Binding Cassette Transporter, Subfamily B , ATP Binding Cassette Transporter, Subfamily B, Member 1/antagonists & inhibitors , ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism , ATP Binding Cassette Transporter, Subfamily G, Member 2 , ATP-Binding Cassette Transporters/metabolism , Animals , Cell Line , Drug Resistance, Neoplasm , Flow Cytometry , High-Throughput Screening Assays , Humans , Inhibitory Concentration 50 , Mice , Mice, SCID , Neoplasm Proteins/metabolism , Small Molecule Libraries , Structure-Activity Relationship , Tumor Burden/drug effects , Xenograft Model Antitumor Assays
16.
Cell Transplant ; 22(10): 1943-54, 2013.
Article in English | MEDLINE | ID: mdl-23069078

ABSTRACT

Organ transplantation is a life-saving procedure and the preferred method of treatment for a growing number of disease states. The advent of new immunosuppressants and improved care has led to great advances in both patient and graft survival. However, acute T-cell-mediated graft rejection occurs in a significant quantity of recipients and remains a life-threatening condition. Acute rejection is associated with decrease in long-term graft survival, demonstrating a need to carefully monitor transplant patients. Current diagnostic criteria for transplant rejection rely on invasive tissue biopsies or relatively nonspecific clinical features. A noninvasive way is needed to detect, localize, and monitor transplant rejection. Capitalizing on advances in targeted contrast agents and magnetic-based detection technology, we developed anti-CD3 antibody-tagged nanoparticles. T cells were found to bind preferentially to antibody-tagged nanoparticles, as identified through light microscopy, transmission electron microscopy, and confocal microscopy. Using mouse skin graft models, we were also able to demonstrate in vivo vascular delivery of T-cell targeted nanoparticles. We conclude that targeting lymphocytes with magnetic nanoparticles is conducive to developing a novel, noninvasive strategy for identifying transplant rejection.


Subject(s)
Antibodies/chemistry , Graft Rejection/diagnosis , Magnetite Nanoparticles/chemistry , Animals , Antibodies/immunology , CD3 Complex/immunology , Graft Rejection/immunology , Humans , Immunohistochemistry , Jurkat Cells , Magnetometry , Male , Mice , Mice, Inbred C57BL , Microscopy, Confocal , Microscopy, Electron, Transmission , Skin/pathology , Skin Transplantation , T-Lymphocytes/immunology , T-Lymphocytes/metabolism , T-Lymphocytes/pathology
17.
Methods Mol Biol ; 910: 195-266, 2012.
Article in English | MEDLINE | ID: mdl-22821598

ABSTRACT

Nuclear Magnetic Resonance (NMR) techniques are widely used in the drug discovery process. The primary feature exploited in these investigations is the large difference in mass between drugs and receptors (usually proteins) and the effect this has on the rotational or translational correlation times for drugs bound to their targets. Many NMR parameters, such as the diffusion coefficient, spin diffusion, nuclear Overhauser enhancement, and transverse and longitudinal relaxation times, are strong functions of either the overall tumbling or translation of molecules in solution. This has led to the development of a wide variety of NMR techniques applicable to the elucidation of protein and nucleic acid structure in solution, the screening of drug candidates for binding to a target of choice, and the study of the conformational changes which occur in a target upon drug binding. High-throughput screening by NMR methods has recently received a boost from the introduction of sophisticated computational techniques for reducing the time needed for the acquisition of the primary NMR data for multidimensional studies.


Subject(s)
Drug Discovery/methods , Magnetic Resonance Spectroscopy/methods , High-Throughput Screening Assays/methods , Models, Molecular , Molecular Structure
18.
Contrast Media Mol Imaging ; 7(3): 308-19, 2012.
Article in English | MEDLINE | ID: mdl-22539401

ABSTRACT

Both magnetic relaxometry and magnetic resonance imaging (MRI) can be used to detect and locate targeted magnetic nanoparticles, noninvasively and without ionizing radiation. Magnetic relaxometry offers advantages in terms of its specificity (only nanoparticles are detected) and the linear dependence of the relaxometry signal on the number of nanoparticles present. In this study, detection of single-core iron oxide nanoparticles by superconducting quantum interference device (SQUID)-detected magnetic relaxometry and standard 4.7 T MRI are compared. The nanoparticles were conjugated to a Her2 monoclonal antibody and targeted to Her2-expressing MCF7/Her2-18 (breast cancer cells); binding of the nanoparticles to the cells was assessed by magnetic relaxometry and iron assay. The same nanoparticle-labeled cells, serially diluted, were used to assess the detection limits and MR relaxivities. The detection limit of magnetic relaxometry was 125 000 nanoparticle-labeled cells at 3 cm from the SQUID sensors. T(2)-weighted MRI yielded a detection limit of 15 600 cells in a 150 µl volume, with r(1) = 1.1 mm(-1) s(-1) and r(2) = 166 mm(-1) s(-1). Her2-targeted nanoparticles were directly injected into xenograft MCF7/Her2-18 tumors in nude mice, and magnetic relaxometry imaging and 4.7 T MRI were performed, enabling direct comparison of the two techniques. Co-registration of relaxometry images and MRI of mice resulted in good agreement. A method for obtaining accurate quantification of microgram quantities of iron in the tumors and liver by relaxometry was also demonstrated. These results demonstrate the potential of SQUID-detected magnetic relaxometry imaging for the specific detection of breast cancer and the monitoring of magnetic nanoparticle-based therapies.


Subject(s)
Breast Neoplasms/diagnosis , Ferric Compounds , Magnetic Resonance Imaging , Magnetite Nanoparticles , Molecular Imaging , Receptor, ErbB-2/immunology , Refractometry/instrumentation , Animals , Antibodies, Monoclonal/immunology , Antibodies, Monoclonal/metabolism , Breast Neoplasms/metabolism , Female , Humans , Mice , Quantum Theory , Receptor, ErbB-2/metabolism , Tumor Cells, Cultured
19.
Breast Cancer Res ; 13(5): R108, 2011 Nov 03.
Article in English | MEDLINE | ID: mdl-22035507

ABSTRACT

INTRODUCTION: Breast cancer detection using mammography has improved clinical outcomes for many women, because mammography can detect very small (5 mm) tumors early in the course of the disease. However, mammography fails to detect 10 - 25% of tumors, and the results do not distinguish benign and malignant tumors. Reducing the false positive rate, even by a modest 10%, while improving the sensitivity, will lead to improved screening, and is a desirable and attainable goal. The emerging application of magnetic relaxometry, in particular using superconducting quantum interference device (SQUID) sensors, is fast and potentially more specific than mammography because it is designed to detect tumor-targeted iron oxide magnetic nanoparticles. Furthermore, magnetic relaxometry is theoretically more specific than MRI detection, because only target-bound nanoparticles are detected. Our group is developing antibody-conjugated magnetic nanoparticles targeted to breast cancer cells that can be detected using magnetic relaxometry. METHODS: To accomplish this, we identified a series of breast cancer cell lines expressing varying levels of the plasma membrane-expressed human epidermal growth factor-like receptor 2 (Her2) by flow cytometry. Anti-Her2 antibody was then conjugated to superparamagnetic iron oxide nanoparticles using the carbodiimide method. Labeled nanoparticles were incubated with breast cancer cell lines and visualized by confocal microscopy, Prussian blue histochemistry, and magnetic relaxometry. RESULTS: We demonstrated a time- and antigen concentration-dependent increase in the number of antibody-conjugated nanoparticles bound to cells. Next, anti Her2-conjugated nanoparticles injected into highly Her2-expressing tumor xenograft explants yielded a significantly higher SQUID relaxometry signal relative to unconjugated nanoparticles. Finally, labeled cells introduced into breast phantoms were measured by magnetic relaxometry, and as few as 1 million labeled cells were detected at a distance of 4.5 cm using our early prototype system. CONCLUSIONS: These results suggest that the antibody-conjugated magnetic nanoparticles are promising reagents to apply to in vivo breast tumor cell detection, and that SQUID-detected magnetic relaxometry is a viable, rapid, and highly sensitive method for in vitro nanoparticle development and eventual in vivo tumor detection.


Subject(s)
Breast Neoplasms/diagnosis , Magnetic Resonance Spectroscopy/methods , Magnetite Nanoparticles , Animals , Breast Neoplasms/metabolism , Cell Line, Tumor , Cell Membrane/immunology , Cell Membrane/metabolism , Female , Ferric Compounds , Humans , Immunoconjugates , Mice , Mice, Nude , Phantoms, Imaging , Receptor, ErbB-2/immunology , Receptor, ErbB-2/metabolism , Sensitivity and Specificity , Xenograft Model Antitumor Assays
20.
J Biol Chem ; 286(23): 20375-86, 2011 Jun 10.
Article in English | MEDLINE | ID: mdl-21515675

ABSTRACT

Ten years ago, we introduced a fluorescent probe that shed light on the inside-out regulation of one of the major leukocyte integrins, very late antigen-4 (VLA-4, CD49d/CD29). Here we describe the regulation of another leukocyte integrin, lymphocyte function-associated antigen-1 (LFA-1, CD11a/CD18) using a novel small fluorescent probe in real time on live cells. We found that multiple signaling mechanisms regulate LFA-1 conformation in a manner analogous to VLA-4. LFA-1 can be rapidly activated by Gα(i)-coupled G protein-coupled receptors (GPCRs) and deactivated by Gα(s)-coupled GPCRs. The effects of Gα(s)-coupled GPCR agonists can be reversed in real time by receptor-specific antagonists. The specificity of the fluorescent probe binding has been assessed in a competition assay using the natural LFA-1 ligand ICAM-1 and the LFA-1-specific α I allosteric antagonist BIRT0377. Similar to VLA-4 integrin, modulation of the ligand dissociation rate can be observed for different LFA-1 affinity states. However, we also found a striking difference in the binding of the small fluorescent ligand. In the absence of inside-out activation ligand, binding to LFA-1 is extremely slow, at least 10 times slower than expected for diffusion-limited binding. This implies that an additional structural mechanism prevents ligand binding to inactive LFA-1. We propose that such a mechanism explains the inability of LFA-1 to support cell rolling, where the absence of its rapid engagement by a counterstructure in the inactive state leads to a requirement for a selectin-mediated rolling step.


Subject(s)
GTP-Binding Protein alpha Subunits, Gi-Go/metabolism , Integrin alpha4beta1/metabolism , Leukocyte Rolling/physiology , Lymphocyte Function-Associated Antigen-1/metabolism , Receptors, G-Protein-Coupled/metabolism , Fluorescent Dyes/chemistry , Humans , Integrin alpha4beta1/agonists , Protein Binding , U937 Cells
SELECTION OF CITATIONS
SEARCH DETAIL
...