22 results on '"Nathan Long"'
Search Results
2. Evolution driven by a varying host environment selects for distinct HIV-1 entry phenotypes and other informative variants
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Shuntai Zhou, Nathan Long, and Ronald Swanstrom
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HIV-1 ,phenotype ,T cell-tropic ,macrophage-tropic ,coreceptor tropism ,drug resistance ,Microbiology ,QR1-502 - Abstract
HIV-1 generates remarkable intra- and inter-host viral diversity during infection. In the response to the dynamic selective pressures of the host’s environment, HIV-1 evolves distinct phenotypes—biological features that provide fitness advantages. The transmitted form of HIV-1 has been shown to require a high density of CD4 on the target cell surface (as found on CD4+ T cells) and typically uses C–C chemokine receptor type 5 (CCR5) as a coreceptor during entry. This phenotype is referred to as R5T cell-tropic (or R5 T-tropic); however, HIV-1 can switch to a secondary coreceptor, C–X–C chemokine receptor type 4 (CXCR4), resulting in a X4T cell-tropic phenotype. Macrophage-tropic (or M-tropic) HIV-1 can evolve to efficiently enter cells expressing low densities of CD4 on their surface (such as macrophages/microglia). So far only CCR5-using M-tropic viruses have been found. M-tropic HIV-1 is most frequently found within the central nervous system (CNS), and infection of the CNS has been associated with neurologic impairment. It has been shown that interferon-resistant phenotypes have a selective advantage during transmission, but the underlying mechanism of this is still unclear. During untreated infection, HIV-1 evolves under selective pressure from both the humoral/antibody response and CD8+ T-cell killing. Sufficiently potent antiviral therapy can suppress viral replication, but if the antiviral drugs are not powerful enough to stop replication, then the replicating virus will evolve drug resistance. HIV-1 phenotypes are highly relevant to treatment efforts, clinical outcomes, vaccine studies, and cure strategies. Therefore, it is critical to understand the dynamics of the host environment that drive these phenotypes and how they affect HIV-1 pathogenesis. This review will provide a comprehensive discussion of HIV-1 entry and transmission, and drug-resistant phenotypes. Finally, we will assess the methods used in previous and current research to characterize these phenotypes.
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- 2023
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3. Evaluating the Rumen Degradation of Novel Protected Gelatin Capsules Containing Fish Oil Fed to Lactating Dairy Cows
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Omar Manuel Pena, Kevin Murphy, Nathan Long, Gustavo J. Lascano, Thomas C. Jenkins, and Matías J. Aguerre
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rumen protection ,EPA ,DHA ,milk fat ,Veterinary medicine ,SF600-1100 ,Zoology ,QL1-991 - Abstract
The objective of this study was to assess the effects of feeding gelatin capsules containing fish oil, treated with alcoholic solutions of flavoring agents followed by drying, on lactation performance, rumen fatty acids content and milk enrichment of fatty acids. In Trial 1, four multiparous ruminally fistulated Holstein cows were randomly assigned to one of four dietary treatments sequences in a 4 × 4 Latin square design. Treatments consisted of (1) Control with no capsules, (2) Control plus 200 untreated capsules per cow/day, mixed with the TMR, (3) Control plus 200 treated capsules per cow/day placed directly into the rumen, (4) Control plus 200 treated capsules per cow/day, mixed with the TMR. In Trial 2, three fistulated Holstein and three fistulated Jersey multiparous cows were randomly assigned to three dietary treatments sequences in a replicated 3 × 3 Latin square design. Treatments consisted of (1) Control with no capsules fed to the cows, (2) Control plus 180 untreated capsules per cow/day, (3) Control plus 180 treated capsules per cow/day. Compared to control, feeding fish oil capsules significantly (Trial 1) or numerically (Trial 2) reduced milk fat concentration and yield. Furthermore, in both trials, the feeding of untreated or treated capsules had no effect on animal performance or milk composition. In both trials, compared to controls, supplementing the diet with fish oil capsules consistently increased total trans C18:1 isomers and DHA concentration in the rumen and milk fat. However, for both trials, capsule protection treatment had a minimal effect on the concentration of any of the reported rumen and milk fatty acids. When assessed under laboratory control conditions, due to water absorption, the treated capsule weight was increased by 40% while resistance to pressure decreased by 84% after 2 h of incubation in water. The results of this study suggest that due to a reduction in the capsule shell’s resistance to abrasion, treated capsules marginally prevented the release of fish oil in the rumen.
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- 2023
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4. If queer theory were my lover
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Nathan Long
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Social Sciences - Abstract
Based on a presentation delivered at the Parameters of Desire conference in Bielsko-Biala, Poland, June 8-11, 2003, "If Queer Theory Were My Lover” attempts to examine the role of queer theory in the academy using a multi-genre-or trans-genre-format, including personal essay, academic essay, questions, humor, performance, and allegorical fiction. Taking an anti-institutional approach, this work explores how the academy affects the physical bodies of those within it, how we as "queer theorists” position ourselves in relation to our queerness and to theory, and if the goal of queer theory is to be accepted by the academy or to challenge it.
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- 2008
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5. 2073. Persistent HIV-1 Viremia Despite Intensive Antiviral Therapy Due to Non-responsive Clonal Viral Lineages
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Shuntai Zhou, Natalie M Bowman, Claire E Farel, Jessica Lin, Jonathan Parr, David A Wohl, Nathan Long, Julie Nelson, Joseph J Eron, Ronald Swanstrom, and Ann Dennis
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Infectious Diseases ,Oncology - Abstract
Background After initiation of antiviral therapy (ART), plasma HIV-1 RNA is usually undetectable after one month. In rare cases, viral suppression may not be achieved despite good adherence and with virus susceptible to ART. We used ultra-deep Primer ID next gen sequencing (NGS) to study the viral population and evolution of HIV-1 in two patients with persistent viremia on intensive ART. Methods We extracted viral RNA from plasma samples collected at multiple timepoints over the duration of the treatment from two patients (VEX1 and VEX2). We constructed Primer ID NGS libraries covering part of the pol gene and the env V1/V3 region and sequenced them on the Illumina MiSeq platform. We used the ‘tcs’ pipeline to construct template consensus sequences (TCS) for each region, and searched for drug resistance mutations (DRMs). The Geno2pheno pipeline was used to predict co-receptor tropisms. Results Patient VEX1 was followed for two years on ART. VEX2 restarted ART in the hospital and received directly observed therapy for nearly 6 months. Both had over 1 million viral copies/mL at the initiation of ART, and the CD4 cell counts were extremely low. Their viral loads slowly declined to approx. 10,000 copies/mL at the end of follow-up but complete viral suppression was not achieved for either patient despite appropriate ART. DRMs were not detected in either patient throughout the treatment with detection sensitivity as low as 0.1%. The sequencing results for VEX1 showed that there were both X4- and R5-tropic viruses at all timepoints and R5 viruses decayed much more slowly than X4 viruses, up to 35-fold more slowly in the initial 3 months of ART. Phylogenetic analysis revealed that the persistent R5 viruses were largely clonal while little clonality was found in the persistent X4 virus. In VEX2, all viruses were R5-tropic. There were three major distinct lineages in the viral population, and two of them completely disappeared after the initiation of ART while the other lineage persisted throughout therapy (Fig 1). The persistent lineage in VEX2 was highly clonal. Pooled maximum likelihood tree at env V1V3 region of 3 time points from patient VEX2. Sequences in red were from 2018 when we obtained the initial specimen from the patient. Sequences in blue were from Sept 2021 when the patient restarted ART. Sequences in green were from Oct 2021 when the patient were on ART for 3 weeks. The patient had 3 major viral lineages, L1, L2, and L3. From 2018 to Sept 2021, we could see the viral evolution of the three lineages (blue arrows). After 3 weeks of ART, L1 and L2 disappeared, while the L3 persisted. We could also see that L3 had several clonal populations which did not respond to ART nor evolve from 2018 to 2021. The additional sequences from Nov 2021 to Feb 2022 were identical to the sequences obtained on Oct 2021 (not shown on this figure). Conclusion Our study shows that persistent viremia on ART can come from clonal viral lineages that carry no DRMs. Clonally expanded and infected host cells might contribute to the phenomenon. Further study is needed to explore the origin of these clonal viral genomes. Disclosures Jonathan Parr, MD, Abbott Laboratories: Donation of laboratory testing and reagents|Gilead Sciences: Grant/Research Support|Virology Education: Honoraria|World Health Organization: Advisor/Consultant|World Health Organization: Grant/Research Support David A. Wohl, M.D., Gilead: Advisor/Consultant|Gilead: Grant/Research Support|Janssen: Advisor/Consultant|Lilly: Grant/Research Support|Merck: Grant/Research Support|ViiV: Advisor/Consultant|ViiV: Grant/Research Support Joseph J. Eron, MD, Adagio Therapeutics: data safety monitoring committee|Gilead Sciences: Advisor/Consultant|Gilead Sciences: Grant/Research Support|Glaxo Smith Kline: Advisor/Consultant|Merck: Advisor/Consultant|ViiV Healthcare: Advisor/Consultant|ViiV Healthcare: Grant/Research Support.
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- 2022
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6. Thiazolidinediones: An In–Depth Study of Their Synthesis and Application to Medicinal Chemistry in the Treatment of Diabetes Mellitus
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Nathan Long, Adam Le Gresley, and Stephen P. Wren
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PPARγ ,endocrine system diseases ,Chemistry, Pharmaceutical ,Pharmacology ,chemistry ,01 natural sciences ,Biochemistry ,Aldehyde Reductase ,Diabetes mellitus ,Drug Discovery ,Diabetes Mellitus ,medicine ,Animals ,Humans ,Hypoglycemic Agents ,General Pharmacology, Toxicology and Pharmaceutics ,Receptor ,Biological sciences ,Protein Tyrosine Phosphatase, Non-Receptor Type 1 ,Aldose reductase ,ALR2 ,010405 organic chemistry ,Chemistry ,Organic Chemistry ,PTP1B ,nutritional and metabolic diseases ,Minireviews ,medicine.disease ,Protein Tyrosine Phosphatase 1B ,0104 chemical sciences ,PPAR gamma ,010404 medicinal & biomolecular chemistry ,Molecular Medicine ,Thiazolidinediones ,Minireview ,Pharmacophore ,biological - Abstract
2,4‐Thiazolidinedione (TZD) is a privileged and highly utilised scaffold for the development of pharmaceutically active compounds. This sulfur‐containing heterocycle is a versatile pharmacophore that confers a diverse range of pharmacological activities. TZD has been shown to exhibit biological action towards a vast range of targets interesting to medicinal chemists. In this review, we attempt to provide insight into both the historical conventional and the use of novel methodologies to synthesise the TZD core framework. Further to this, synthetic procedures utilised to substitute the TZD molecule at the activated methylene C5 and N3 position are reviewed. Finally, research into developing clinical agents, which act as modulators of peroxisome proliferator‐activated receptors gamma (PPARγ), protein tyrosine phosphatase 1B (PTP1B) and aldose reductase 2 (ALR2), are discussed. These are the three most targeted receptors for the treatment of diabetes mellitus (DM)., A key scaffold: 2,4‐Thiazolidinedione is a widely recognised structural motif present in many therapeutic agents used for the treatment of diabetes mellitus. This review summarises some of the methods used to prepare biologically active members of this class and discusses the pharmacological potency of these compounds.
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- 2021
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7. Eclipse stemless shoulder prosthesis vs. Univers II shoulder prosthesis: a multicenter, prospective randomized controlled trial
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Joshua Port, Earl McFadden, Jeffrey Klassen, Brandon J. Erickson, John W. Brown, William Tyndall, Arash Araghi, Jason Stein, Brian S. Cohen, Joseph A. Abboud, Nikhil N. Verma, Benjamin Sears, Mark C. Smith, Anthony A. Romeo, Thomas A. Brandon, Nathan Long, Paul Patterson, John G. Costouros, and Kevin J Setter
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Adult ,Male ,medicine.medical_specialty ,medicine.medical_treatment ,Bone Screws ,Arthritis ,Osteoarthritis ,Prosthesis ,law.invention ,Young Adult ,03 medical and health sciences ,Postoperative Complications ,0302 clinical medicine ,Randomized controlled trial ,law ,medicine ,Humans ,Orthopedics and Sports Medicine ,Prospective Studies ,Aged ,Aged, 80 and over ,030222 orthopedics ,Shoulder Joint ,business.industry ,Shoulder Prosthesis ,Equipment Design ,030229 sport sciences ,General Medicine ,Middle Aged ,medicine.disease ,Arthroplasty ,United States ,Surgery ,Treatment Outcome ,Arthroplasty, Replacement, Shoulder ,Trunnion ,Female ,Implant ,business - Abstract
Background Total shoulder arthroplasty is an accepted treatment for glenohumeral osteoarthritis. The Arthrex Eclipse shoulder prosthesis is a stemless, canal-sparing humeral prosthesis with bone ingrowth capacity on the trunnion, as well as through the fenestrated hollow screw, that provides both diaphyseal and metaphyseal load sharing and fixation. Methods Between 2013 and 2018, 16 sites in the United States enrolled 327 patients (Eclipse in 237 and Arthrex Univers II in 90). All patients had glenohumeral arthritis refractory to nonsurgical care. Strict exclusion criteria were applied to avoid confounding factors such as severe patient comorbidities, arthritis not consistent with osteoarthritis, and medical or prior surgical treatments that may have affected outcomes. Patients were randomized to the Eclipse or Univers II group via block randomization. Results In total, 149 Eclipse and 76 Univers II patients reached 2-year follow-up (139 Eclipse patients [93.3%] and 68 Univers II patients [89.5%] had complete data). The success rate using the Composite Clinical Success score was 95% in the Eclipse group vs. 89.7% in the Univers II group. No patient exhibited radiographic evidence of substantial humeral radiolucency, humeral migration, or subsidence at any point. Reoperations were performed in 7 patients (3.2%) in the Eclipse group and 3 (3.8%) in the Univers II group. Conclusion The Arthrex Eclipse shoulder prosthesis is a safe and effective humeral implant for patients with glenohumeral arthritis at 2-year follow-up, with no differences in outcomes compared with the Univers II shoulder prosthesis.
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- 2020
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8. Tamoxifen and ICI 182,780 activate hypothalamic G protein-coupled estrogen receptor 1 to rapidly facilitate lordosis in female rats
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Asma Mana, Nathan Long, Lam Nguyen, Dream Le, Kevin Sinchak, Bertha Long, and Sima Chokr
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Male ,0301 basic medicine ,medicine.medical_specialty ,Estrogen receptor ,Article ,Receptors, G-Protein-Coupled ,03 medical and health sciences ,Behavioral Neuroscience ,chemistry.chemical_compound ,0302 clinical medicine ,Endocrinology ,Internal medicine ,medicine ,Animals ,Rats, Long-Evans ,Receptor ,Fulvestrant ,Estradiol ,Endocrine and Autonomic Systems ,Chemistry ,Arcuate Nucleus of Hypothalamus ,Stimulation, Chemical ,Rats ,Tamoxifen ,030104 developmental biology ,Selective estrogen receptor modulator ,Metabotropic glutamate receptor ,Hypothalamus ,G-Protein Coupled Estrogen Receptor 1 ,Lordosis ,Estradiol benzoate ,Female ,GPER ,hormones, hormone substitutes, and hormone antagonists ,030217 neurology & neurosurgery - Abstract
In the female rat, sexual receptivity (lordosis) can be facilitated by sequential activation of estrogen receptor (ER) α and G protein-coupled estrogen receptor 1 (GPER) by estradiol. In the estradiol benzoate (EB) primed ovariectomized (OVX) rat, EB initially binds to ERα in the plasma membrane that complexes with and transactivates metabotropic glutamate receptor 1a to activate β-endorphin neurons in the arcuate nucleus of the hypothalamus (ARH) that project to the medial preoptic nucleus (MPN). This activates MPN μ-opioid receptors (MOP), inhibiting lordosis. Infusion of non-esterified 17β-estradiol into the ARH rapidly reduces MPN MOP activation and facilitates lordosis via GPER. Tamoxifen (TAM) and ICI 182,780 (ICI) are selective estrogen receptor modulators that activate GPER. Therefore, we tested the hypothesis that TAM and ICI rapidly facilitate lordosis via activation of GPER in the ARH. Our first experiment demonstrated that injection of TAM intraperitoneal, or ICI into the lateral ventricle, deactivated MPN MOP and facilitated lordosis in EB-primed rats. We then tested whether TAM and ICI were acting rapidly through a GPER dependent pathway in the ARH. In EB-primed rats, ARH infusion of either TAM or ICI facilitated lordosis and reduced MPN MOP activation within 30 min compared to controls. These effects were blocked by pretreatment with the GPER antagonist, G15. Our findings demonstrate that TAM and ICI deactivate MPN MOP and facilitate lordosis in a GPER dependent manner. Thus, TAM and ICI may activate GPER in the CNS to produce estrogenic actions in neural circuits that modulate physiology and behavior.
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- 2017
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9. Pensions Regulator fines thousands of firms
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Nathan Long
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Labour economics ,Care homes ,Regulator ,General Medicine ,Business - Abstract
Pensions automatic enrolment is 5 years old. While the rollout is complete, employers duties are ongoing. With stiff penalties for non-compliance, care homes need to understand their obligations towards their employees' pensions
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- 2018
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10. 25 Effects of post-weaning supplementation of immunomodulatory feed ingredient on cortisol concentrations and microbial populations in programmed fed beef heifers
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Keelee J McCarty, Jessie Tipton, Ralph Ricks, Jessica L Danielo, Jesse Thompson, and Nathan Long
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Abstracts ,animal structures ,animal diseases ,Genetics ,Animal Science and Zoology ,General Medicine ,Food Science - Abstract
The objective was to determine the effects of immunomodulatory feed ingredient during post-weaning on cortisol concentration and fecal microbial populations of beef heifers. Commercial Angus heifers (n = 72) from two AI sires were blocked (n = 9) by sire and BW, randomly assigned to one of two pens (4 heifers/pen) per block, then assigned to treatments. Heifers were fed twice daily from d 0 to 60 (gain 0.75 kg/day) and topdressed once daily with either 72g of Celmanax (CEL) or corn germ (CON; corn germ meal) per pen. After 60 days, two heifers per pen (n = 32) were randomly selected for a transportation challenge. Fecal grab samples were collected on d 0 and 69 of treatment, hr -24, 0, 24 of the challenge and 7 d post-challenge. Serum samples were collected at h 0, 4, 8, and 12 of the challenge. Clostridia and E. coli were enumerated from fecal samples using selective media. Isolates (≤ five isolates from each media per sample) were genetically tested to determine if they were C. perfringens or pathogenic E. coli. Fecal samples were enriched for detection of Salmonella. Pen was the experimental unit and data was analyzed by ANOVA or repeated measures analysis. Following treatment, decreased (P ≤ 0.05) populations of total E. coli, Salmonella, and C. perfringens were observed in CEL heifers compared to CON heifers, whereas clostridia and pathogenic E. coli were not different (P > 0.05) between treatments. Transportation stress increased (P ≤ 0.05) populations of clostridia, C. perfringens, total E. coli, and Salmonella, but decreased (P = 0.0252) pathogenic E. coli counts. Cortisol concentrations were decreased (P < 0.05) in CEL heifers compared to CON heifers throughout the challenge. In summary, supplementation of Celmanax post-weaning altered microbial populations and cortisol concentrations were reduced during transportation in beef heifers
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- 2019
11. Regenerative Dynamic Soaring Trajectory Augmentation over Flat Terrains
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Vincent Bonnin, Simon C. Watkins, Nathan Long, and Jean-Marc Moschetta
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business.industry ,Trajectory ,Terrain ,Aerospace engineering ,business ,Geology ,Dynamic soaring - Published
- 2019
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12. Auto-enrolment and the new pension landscape
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Nathan Long
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Labour economics ,Pension ,Political science ,General Medicine - Abstract
Workplace pensions have changed radically over the last few years, and will continue to do so until at least February 2018. In this article, Nathan Long explains the obligations that employers are under, and how these are likely to change over the next few years
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- 2017
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13. 17β-estradiol rapidly facilitates lordosis through G protein-coupled estrogen receptor 1 (GPER) via deactivation of medial preoptic nucleus μ-opioid receptors in estradiol primed female rats
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Kevin Sinchak, Chhorvann Serey, and Nathan Long
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Male ,Agonist ,medicine.medical_specialty ,medicine.drug_class ,Posture ,Receptors, Opioid, mu ,Estrogen receptor ,Biology ,Article ,Receptors, G-Protein-Coupled ,Sexual Behavior, Animal ,Behavioral Neuroscience ,chemistry.chemical_compound ,Endocrinology ,Internal medicine ,medicine ,Animals ,Rats, Long-Evans ,Receptor ,Neurons ,Estradiol ,Endocrine and Autonomic Systems ,Arcuate Nucleus of Hypothalamus ,food and beverages ,Immunohistochemistry ,Preoptic Area ,Rats ,Preoptic area ,nervous system ,chemistry ,Hypothalamus ,Estradiol benzoate ,Ovariectomized rat ,Female ,GPER - Abstract
In female rats sexual receptivity (lordosis) can be induced with either a single large dose of estradiol benzoate (EB), or a priming dose of EB that does not induce sexual receptivity followed by 17β-estradiol (E2). Estradiol priming initially inhibits lordosis through a multi-synaptic circuit originating in the arcuate nucleus of the hypothalamus (ARH) that activates and internalizes μ-opioid receptors (MOR) in medial preoptic nucleus (MPN) neurons. Lordosis is facilitated when MPN MOR are deactivated after the initial estradiol-induced activation. We tested the hypothesis that E2 given 47.5 hours post EB acts rapidly through G protein-coupled estrogen receptor 1 (GPER) in the ARH to deactivate MPN MOR and facilitate lordosis. Ovariectomized Long Evans rats implanted with a third ventricle cannula were primed with 2 μg EB. DMSO control, E2, or G1 (GPER selective agonist) was infused 47.5 hours later, and rats were tested for sexual receptivity. E2 and G1 infusions significantly increased levels of sexual receptivity compared to DMSO controls and pretreatment with G15 (GPER antagonist) blocked the facilitation of sexual receptivity. Brains were processed for MPN MOR immunohistochemistry to measure MPN MOR activation levels. E2 and G1 both significantly reduced MPN MOR activation compared to DMSO controls, while pretreatment with G15 blocked MPN MOR deactivation. In another group of EB treated ovariectomized rats, GPER immunofluorescence positive staining was observed throughout the ARH. Together these data indicate that in the 2 μg EB primed rat, E2 rapidly signals through GPER in the ARH to deactivate MPN MOR and facilitate lordosis.
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- 2014
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14. A long-term flexible minimally-invasive implantable glucose biosensor based on an epoxy-enhanced polyurethane membrane
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Bazhang Yu, Francis Moussy, Yvonne Moussy, and Nathan Long
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Blood Glucose ,Materials science ,Polyurethanes ,Biomedical Engineering ,Biophysics ,Biosensing Techniques ,Glucose Oxidase ,chemistry.chemical_compound ,Coated Materials, Biocompatible ,In vivo ,Polymer chemistry ,Electrochemistry ,Animals ,Polyurethane ,Blood Glucose Self-Monitoring ,Membranes, Artificial ,Equipment Design ,Prostheses and Implants ,General Medicine ,Epoxy ,Enzymes, Immobilized ,Durability ,Elasticity ,Rats ,Equipment Failure Analysis ,Membrane ,chemistry ,visual_art ,visual_art.visual_art_medium ,Epoxy Compounds ,Cattle ,Implant ,Adhesive ,Biosensor ,Biotechnology ,Biomedical engineering - Abstract
This paper describes the preparation method as well as the in vitro and in vivo evaluation of a novel flexible glucose biosensor designed for long-term subcutaneous implantation. An epoxy-enhanced polyurethane membrane, which includes ca. 30-40% epoxy resin adhesive and 50-70% polyurethane, has been developed and used for the first time as the outer protective membrane of the sensor. This new membrane was developed to increase the in vivo durability and lifetime of implantable biosensors. This epoxy-polyurethane membrane was shown to be porous and is of excellent durability. A sensor with such a membrane shows excellent long-term stability and can last for 4-8 months in solutions at room temperature. To verify the in vivo performance of the sensor, nine sensors were implanted in three rats and tested regularly. Eight sensors kept functioning well in the rats for 10-56 days. The ninth sensor was damaged during implantation. All original sensitivity data as well as four response curves obtained at days 7, 17, 52 and 56, respectively are presented.
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- 2006
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15. Strategies for Testing Long-Term Transcutaneous Amperometric Glucose Sensors
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Yvonne Moussy, Francis Moussy, Bazhang Yu, and Nathan Long
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Blood Glucose ,Male ,business.industry ,Endocrinology, Diabetes and Metabolism ,Biosensing Techniques ,Amperometry ,Rats ,Rats, Sprague-Dawley ,Medical Laboratory Technology ,Endocrinology ,Diabetes Mellitus ,Animals ,Medicine ,Glucose sensors ,business ,Monitoring, Physiologic ,Biomedical engineering - Abstract
Transcutaneous and embedded devices were developed for use in characterizing the in vivo performance of subcutaneously implanted glucose sensors. The devices were used as a portal for accessing electrochemical glucose sensors from the exterior. They were designed to prevent the sensors from being pulled out of the animals and the sensor leads from breaking. Development of the devices took into consideration rodent mobility, infection control, and animal welfare balanced with sensor durability, accessibility, and functionality.Our approach was developed over five animal protocols spanning a period of 6 months. A total of 68 sensors were implanted with 60 associated devices in 22 Sprague-Dawley outbred rats.The average sensor lifetime was 11.2 +/- 3.1 days with a maximum of 56 days. All-cause sensor failure averaged one sensor per day. As implantation devices were modified, failure attributable to the device was decreased by 40%. The resulting devices showed good durability and allowed for easy sensor access and testing.These data represent baseline sensor function against which future sensor improvements may be measured. The new devices and techniques described should be a valuable tool in the development of continuous glucose sensors.
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- 2005
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16. The Role of Leptin and Its Regulation in the Hypothalamus of Neonatal Calves.
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Nathan Long and McCarty, Keelee J.
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HEIFERS , *CALVES , *LEPTIN , *FETAL growth retardation , *HYPOTHALAMUS , *GROWTH factors , *PARTURITION - Abstract
The constant occurrence of increased feed intake in offspring exposed to intrauterine growth restriction has been noted across multiple species including ruminants. In ruminants, reduced circulating leptin concentrations from birth through the first week or two of life may influence the development of the appetite center of the hypothalamus. It should able be noted that increased circulating cortisol at birth has been associated with this decreased circulating leptin in the perinatal ruminants, yet information is limited as to any cause and effect relationship between the two hormones. The objectives of these studies were to test directly the effects of exogenous cortisol on leptin concentrations relative to development of the hypothalamus in perinatal calves and voluntary feed intake as yearling. In two experiments, Holstein bulls (n = 27) and calves (n = 32 males; n = 30 females) from commercial Angus cows were assigned to treatments at parturition (day 0). Calves were intravenously infused with either a low cortisol [LC; n = 9, 3.5 ug/kg of body weight (BW)], high cortisol (HC; n = 9, 7.0 ug/kg BW), or a control (CON; n = 9, saline). Calves were administered a half dose of their respective treatment 24h postpartum. Jugular vein blood samples were collected before infusion and daily until d 17 or necropsy. At 5 days of age Holstein bull calves were euthanized where cerebral-spinal fluid (CSF) and hypothalamic tissue were collected. Serum and CSF leptin concentrations were analyzed via RIA. Neuronal growth factors were analyzed in hypothalamus samples via qRT-PCR. In experiment 2, yearling calves entered a GROWSAFE System and daily feed intake (FI) measured. Animals were allowed a twoweek adjustment period to a growing ration for heifers and a finishing ration for steers. Heifer body condition scores (BCS) were collected at the beginning and end of the trial. Heifers underwent the feeding trial for 70 days and steers until they obtained a back fat (BF) thickness of 1.15 cm. Blood samples were analyzed similar to experiment 1. All data were analyzed via repeated measures using appropriate models of SAS (SAS Institute Inc., Cary, NC). Perinatal dairy bull calves had decreased (P < 0.013) serum and CSF leptin concentrations of HC and LC calves compared with CON. Hypothalamic expression of BDNF, FGF1 and FGF2 were decreased (P < 0.006) in HC and LC compared with CON. During the feeding trial: BW gain, BCS change, and number of feed events were increased (P = 0.001) in LC compared with HC and CON heifers. However, LC observed greater daily FI (P = 0.047) and tended to have greater final BW (P = 0.080) compared with HC and CON steers. In summary, these data support that exogenous cortisol administered to perinatal calves affects leptin production and the appetite center of the hypothalamus when administered during the neonatal period. [ABSTRACT FROM AUTHOR]
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- 2023
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17. Gradual Painless Visual Loss: Chronic Optic Neuropathies
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Susan C. Benes and Nathan Long
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medicine.medical_specialty ,genetic structures ,medicine.diagnostic_test ,business.industry ,Physical examination ,Disease ,Fluorescein angiography ,medicine.disease ,eye diseases ,Surgery ,Atrophy ,medicine ,Optic nerve ,Etiology ,Cranial nerve disease ,Medical history ,Geriatrics and Gerontology ,medicine.symptom ,Intensive care medicine ,business - Abstract
The clinician must be the ultimate medical detective when dealing with chronic optic neuropathies. History taking is crucial. Clinical examination may require supplementation with visual field testing, fluorescein angiography, ocular and orbital ultrasound imaging, CT and MR imaging, blood test data, and cerebrospinal fluid or tissue biopsy data to determine the specific diagnosis. This supplementation is labor-intensive and time-consuming; the visual loss usually will progress throughout the process, frustrating and frightening the patient and physician. The final common pathway is gradual optic atrophy; the appearance of the optic nerve is rarely adequate to determine the cause of the visual loss. This article includes tables that review diagnostic aids and therapies, and lists the frequency with which several disease entities were encountered over 15 years in one tertiary care neuro-ophthalmic practice. If a specific cause is discernible, then a specific therapy may be available. This approach has the best chance of saving the patient‘s vision with the least toxicity caused by erroneous trials. By necessity, the work-up for these patients is expensive, but the cost of not pursuing the cause is irrevocable, permanent blindness.
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- 1999
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18. Swords of Waar
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Nathan Long and Nathan Long
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- Human-alien encounters--Fiction, Voyages, Imaginary--Fiction
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Jane Carver, a hell-raising, redheaded biker chick from Coral Gables, Florida, had found a new life and love on Waar, a savage planet of fearsome creatures and swashbuckling warriors. Until the planet's high priests sent her back to Earth against her will.But nobody keeps Jane from her man, even if he happens to be a purple-skinned alien nobleman.Against all odds, she returns to Waar, only to find herself accused of kidnaping the Emperor's beautiful daughter. Allying herself with a band of notorious sky-pirates, Jane sets out to clear her name and rescue the princess, but that means uncovering the secret origins of the Gods of Waar–and picking a fight with the Wargod himself.Good thing Jane is always up for a scrap....Swords of Waar is the wildly entertaining sequel to Jane Carver of Waar, and continues the raucous adventures of science fiction's newest and most bad ass space heroine.
- Published
- 2012
19. Jane Carver of Waar
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Nathan Long and Nathan Long
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- Gladiators--Fiction, Women motorcyclists--Fiction, Extraterrestrial beings--Fiction, Interplanetary voyages--Fiction
- Abstract
Jane Carver is nobody's idea of a space princess.A hard-ridin', hard-lovin'biker chick and ex-Airborne Ranger, Jane is as surprised as anyone else when, on the run from the law, she ducks into the wrong cave at the wrong time-and wakes up butt-naked on an exotic alien planet light-years away from everything she's ever known.Waar is a savage world of four-armed tiger-men, sky-pirates, slaves, gladiators, and purple-skinned warriors in thrall to a bloodthirsty code of honor and chivalry. Caught up in a disgraced nobleman's quest to win back the hand of a sexy alien princess, Jane encounters bizarre wonders and dangers unlike anything she ever ran into back home.Then again, Waar has never seen anyone like Jane before…Both a loving tribute and scathing parody of the swashbuckling space fantasies of yore, Jane Carver of Waar introduces an unforgettable new science fiction heroine.
- Published
- 2012
20. Study of the effects of tissue reactions on the function of implanted glucose sensors
- Author
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Nathan Long, Paul Dungel, Bazhang Yu, Yvonne Moussy, and Francis Moussy
- Subjects
Blood Glucose ,Surgical Sponges ,Materials science ,In vivo degradation ,Biomedical Engineering ,Monitoring, Ambulatory ,Neovascularization, Physiologic ,Fibrous capsule ,Polyvinyl alcohol ,Biomaterials ,chemistry.chemical_compound ,Implants, Experimental ,In vivo ,Materials Testing ,Animals ,Glucose sensors ,biology ,Blood Glucose Self-Monitoring ,Metals and Alloys ,biology.organism_classification ,Rats ,Sponge ,chemistry ,Polyvinyl Alcohol ,Ceramics and Composites ,Collagen ,Biomedical engineering - Abstract
The relationship between tissue reactions to a subcutaneously implanted glucose sensor and the function of the sensor was evaluated over a period of 4-weeks using tubular, porous polyvinyl alcohol (PVA) sponges implanted subcutaneously in rats. The PVA sponges were used as scaffolds in which the foreign body response could develop. Coil-type glucose sensors were then placed in the center of the PVA sponges and tested on day 3, and weekly thereafter. In the first approach, the sensors were placed in the sponges still implanted in the rats and tested. In vivo glucose sensor sensitivity peaked at day 7 and steadily decreased until day 35. In the second approach, the sensors were placed in the explanted sponges and then tested. This test showed no sensor function after day 7, indicating that functional blood vessels are critical in maintaining any function whatsoever. In both cases the sensors themselves were never implanted to eliminate any potential in vivo degradation of the sensors that could have affected the outcome of this study. Sensors were then tested in absence of sponges and found to be working properly with no change from preimplantation sensitivity. Once sensor testing was concluded, the PVA sponge/tissue samples were prepared for quantitative histological analysis. It was determined that the increase in collagen deposition within the sponge correlated with the decrease in sensor sensitivity. It was also observed that natural angiogenesis (peak at day 14) did not overcome the barrier to glucose diffusion created by the fibrous capsule. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
- Published
- 2007
21. Strategies for Testing Long-Term TranscutaneousAmperometric Glucose Sensors.
- Author
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Nathan Long, Bazhang Yu, Yvonne Moussy, and Francis Moussy
- Published
- 2005
22. Pairwise-Distance-Analysis-Driven Dimensionality Reduction Model with Double Mappings for Hyperspectral Image Visualization
- Author
-
Yi Long, Heng-Chao Li, Turgay Celik, Nathan Longbotham, and William J. Emery
- Subjects
hyperspectral image visualization ,dimensionality reduction ,multidimensionalscaling ,human visual system ,Science - Abstract
This paper describes a novel strategy for the visualization of hyperspectral imagery based on the analysis of image pixel pairwise distances. The goal of this approach is to generate a final color image with excellent interpretability and high contrast at the cost of distorting a few pairwise distances. Specifically, the principle of equal variance is introduced to divide all hyperspectral bands into three subgroups and to ensure the energy is distributed uniformly between them, as in natural color images. Then, after detecting both normal and outlier pixels, these three subgroups are mapped into three color components of the output visualization using two different mapping (i.e., dimensionality reduction) schemes for the two types of pixels. The widely-used multidimensional scaling (MDS) is used for normal pixels and a new objective function, taking into account the weighting of pairwise distances, is presented for the outlier pixels. The pairwise distance weighting is designed such that small pairwise distances between the outliers and their respective neighbors are emphasized and large deviations are suppressed. This produces an image with high contrast and good interpretability while retaining the detailed information content. The proposed algorithm is compared with several state-of-the-art visualization techniques and evaluated on the well-known AVIRIS hyperspectral images. The effectiveness of the proposed strategy is substantiated both visually and quantitatively.
- Published
- 2015
- Full Text
- View/download PDF
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