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1.
Nephrol Dial Transplant ; 39(3): 426-435, 2024 Feb 28.
Artículo en Inglés | MEDLINE | ID: mdl-37573145

RESUMEN

BACKGROUND: There are no consensus definitions for evaluating kidney function recovery after acute kidney injury (AKI) and acute kidney disease (AKD), nor is it clear how recovery varies across populations and clinical subsets. We present a federated analysis of four population-based cohorts from Canada, Denmark and Scotland, 2011-18. METHODS: We identified incident AKD defined by serum creatinine changes within 48 h, 7 days and 90 days based on KDIGO AKI and AKD criteria. Separately, we applied changes up to 365 days to address widely used e-alert implementations that extend beyond the KDIGO AKI and AKD timeframes. Kidney recovery was based on resolution of AKD and a subsequent creatinine measurement below 1.2× baseline. We evaluated transitions between non-recovery, recovery and death up to 1 year; within age, sex and comorbidity subgroups; between subset AKD definitions; and across cohorts. RESULTS: There were 464 868 incident cases, median age 67-75 years. At 1 year, results were consistent across cohorts, with pooled mortalities for creatinine changes within 48 h, 7 days, 90 days and 365 days (and 95% confidence interval) of 40% (34%-45%), 40% (34%-46%), 37% (31%-42%) and 22% (16%-29%) respectively, and non-recovery of kidney function of 19% (15%-23%), 30% (24%-35%), 25% (21%-29%) and 37% (30%-43%), respectively. Recovery by 14 and 90 days was frequently not sustained at 1 year. Older males and those with heart failure or cancer were more likely to die than to experience sustained non-recovery, whereas the converse was true for younger females and those with diabetes. CONCLUSION: Consistently across multiple cohorts, based on 1-year mortality and non-recovery, KDIGO AKD (up to 90 days) is at least prognostically similar to KDIGO AKI (7 days), and covers more people. Outcomes associated with AKD vary by age, sex and comorbidities such that older males are more likely to die, and younger females are less likely to recover.


Asunto(s)
Lesión Renal Aguda , Riñón , Masculino , Femenino , Humanos , Anciano , Creatinina , Estudios de Cohortes , Enfermedad Aguda , Lesión Renal Aguda/epidemiología , Lesión Renal Aguda/etiología , Estudios Retrospectivos
2.
BMC Psychiatry ; 23(1): 22, 2023 01 11.
Artículo en Inglés | MEDLINE | ID: mdl-36627578

RESUMEN

BACKGROUND: One in eight children in the United Kingdom are estimated to have a mental health condition, and many do not receive support or treatment. The COVID-19 pandemic has negatively impacted mental health and disrupted the delivery of care. Prevalence of poor mental health is not evenly distributed across age groups, by sex or socioeconomic groups. Equity in access to mental health care is a policy priority but detailed socio-demographic trends are relatively under-researched. METHODS: We analysed records for all mental health prescriptions and referrals to specialist mental health outpatient care between the years of 2015 and 2021 for children aged 2 to 17 years in a single NHS Scotland health board region. We analysed trends in prescribing, referrals, and acceptance to out-patient treatment over time, and measured differences in treatment and service use rates by age, sex, and area deprivation. RESULTS: We identified 18,732 children with 178,657 mental health prescriptions and 21,874 referrals to specialist outpatient care. Prescriptions increased by 59% over the study period. Boys received double the prescriptions of girls and the rate of prescribing in the most deprived areas was double that in the least deprived. Mean age at first mental health prescription was almost 1 year younger in the most deprived areas than in the least. Referrals increased 9% overall. Initially, boys and girls both had an annual referral rate of 2.7 per 1000, but this fell 6% for boys and rose 25% for girls. Referral rate for the youngest decreased 67% but increased 21% for the oldest. The proportion of rejected referrals increased steeply since 2020 from 17 to 30%. The proportion of accepted referrals that were for girls rose to 62% and the mean age increased 1.5 years. CONCLUSIONS: The large increase in mental health prescribing and changes in referrals to specialist outpatient care aligns with emerging evidence of increasing poor mental health, particularly since the start of the COVID-19 pandemic. The static size of the population accepted for specialist treatment amid greater demand, and the changing demographics of those accepted, indicate clinical prioritisation and unmet need. Persistent inequities in mental health prescribing and referrals require urgent action.


Asunto(s)
COVID-19 , Atención Secundaria de Salud , Masculino , Femenino , Niño , Humanos , Lactante , Datos de Salud Recolectados Rutinariamente , Salud Mental , Pandemias , COVID-19/epidemiología , Derivación y Consulta
3.
Ann Surg Oncol ; 28(12): 7809-7820, 2021 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-34041626

RESUMEN

BACKGROUND: Epithelial appendiceal neoplasms are uncommon peritoneal malignancies causing a spectrum of disease including pseudomyxoma peritonei (PMP). The optimal management is cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC). Despite complete CRS (CCRS), recurrence develops in almost 45% of patients. No consensus exists for the optimal treatment of recurrent disease, with treatment strategies including repeat CRS, watch-and-wait, and palliative chemotherapy. This report aims to describe evolving management strategies for a large cohort with recurrence after CCRS. METHODS: This retrospective study analyzed a prospective database of patients with recurrence after CCRS for appendiceal neoplasms from 1994 to 2017 who had long-term follow-up evaluation with tumor markers and computed tomography (CT). RESULTS: Overall, 430 (37.6%) of 1145 PMP patients experienced recurrence at a median of 19 months. Of these 430 patients 145 (33.7%) underwent repeat CRS, 119 (27.7%) had a watch-and-wait approach, and 119 (27.7%) had palliative chemotherapy. The patients with recurrence had a median overall survival (OS) of 39 months, a 3-year survival of 74.6%, a 5-year survival of 57.4%, and a 10-year survival of 36.5%. In the multivariate analysis, the patients who had recurrence within 1 year after primary CRS (hazard ratio [HR], 3.55), symptoms at recurrence (HR, 3.08), a high grade of disease or adenocarcinoma pathology (HR, 2.94), signet ring cells (HR, 1.91), extraperitoneal metastatic disease (HR, 1.71), or male gender (HR, 1.61) had worse OS. The OS was longer for the patients who had repeat CRS (HR, 0.41). The patients who underwent repeat CCRS had a 3-year OS of 87.5%, a 5-year OS of 78.1%, and a 10-year OS of 67.9%. CONCLUSIONS: Dilemmas persist around the optimal management of patients with recurrence after CRS and HIPEC for appendiceal tumors. Selected patients benefit from repeat CRS, particularly those with favorable tumor biology and focal disease.


Asunto(s)
Neoplasias del Apéndice , Hipertermia Inducida , Seudomixoma Peritoneal , Cirujanos , Neoplasias del Apéndice/terapia , Terapia Combinada , Procedimientos Quirúrgicos de Citorreducción , Humanos , Quimioterapia Intraperitoneal Hipertérmica , Masculino , Recurrencia Local de Neoplasia/terapia , Seudomixoma Peritoneal/tratamiento farmacológico , Estudios Retrospectivos , Tasa de Supervivencia
4.
Environ Sci Technol ; 55(4): 2585-2596, 2021 02 16.
Artículo en Inglés | MEDLINE | ID: mdl-33523627

RESUMEN

Filter performance can be affected by bacterial colonization of the filtration media, yet little is known about how naturally occurring bacteria modify the surface properties of filtration media to affect colloidal removal. We used sand columns and simulated stormwater conditions to study the retention of model colloidal particles, carboxyl-modified-latex (CML) beads, in porous media colonized by naturally occurring bacterial strains. Colloid retention varied substantially across identical columns colonized by different, in some cases closely related, bacterial strains in a cell density independent manner. Atomic force microscopy was applied to quantify the interaction energy between CML beads and each bacterial strain's biofilm surface. We found interaction energy between CML and each strain was significantly different, with adhesive energies between the biofilm and CML, presumed to be associated with polymer-surface bonding, a better predictor of CML retention than other strain characteristics. Overall, the findings suggest that interactions with biopolymers in naturally occurring bacterial biofilms strongly influence colloid retention in porous media. This work highlights the need for more investigation into the role of biofilm microbial community composition on colloid removal in porous media to improve biofilter design and operation.


Asunto(s)
Biopelículas , Coloides , Filtración , Porosidad , Propiedades de Superficie
5.
Ecol Modell ; 465: 1-109635, 2021 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-34675451

RESUMEN

The Chesapeake Bay is the largest, most productive, and most biologically diverse estuary in the continental United States providing crucial habitat and natural resources for culturally and economically important species. Pressures from human population growth and associated development and agricultural intensification have led to excessive nutrient and sediment inputs entering the Bay, negatively affecting the health of the Bay ecosystem and the economic services it provides. The Chesapeake Bay Program (CBP) is a unique program formally created in 1983 as a multi-stakeholder partnership to guide and foster restoration of the Chesapeake Bay and its watershed. Since its inception, the CBP Partnership has been developing, updating, and applying a complex linked modeling system of watershed, airshed, and estuary models as a planning tool to inform strategic management decisions and Bay restoration efforts. This paper provides a description of the 2017 CBP Modeling System and the higher trophic level models developed by the NOAA Chesapeake Bay Office, along with specific recommendations that emerged from a 2018 workshop designed to inform future model development. Recommendations highlight the need for simulation of watershed inputs, conditions, processes, and practices at higher resolution to provide improved information to guide local nutrient and sediment management plans. More explicit and extensive modeling of connectivity between watershed landforms and estuary sub-areas, estuarine hydrodynamics, watershed and estuarine water quality, the estuarine-watershed socioecological system, and living resources will be important to broaden and improve characterization of responses to targeted nutrient and sediment load reductions. Finally, the value and importance of maintaining effective collaborations among jurisdictional managers, scientists, modelers, support staff, and stakeholder communities is emphasized. An open collaborative and transparent process has been a key element of successes to date and is vitally important as the CBP Partnership moves forward with modeling system improvements that help stakeholders evolve new knowledge, improve management strategies, and better communicate outcomes.

6.
N Engl J Med ; 371(8): 699-710, 2014 Aug 21.
Artículo en Inglés | MEDLINE | ID: mdl-25140956

RESUMEN

BACKGROUND: Silent cerebral infarcts are the most common neurologic injury in children with sickle cell anemia and are associated with the recurrence of an infarct (stroke or silent cerebral infarct). We tested the hypothesis that the incidence of the recurrence of an infarct would be lower among children who underwent regular blood-transfusion therapy than among those who received standard care. METHODS: In this randomized, single-blind clinical trial, we randomly assigned children with sickle cell anemia to receive regular blood transfusions (transfusion group) or standard care (observation group). Participants were between 5 and 15 years of age, with no history of stroke and with one or more silent cerebral infarcts on magnetic resonance imaging and a neurologic examination showing no abnormalities corresponding to these lesions. The primary end point was the recurrence of an infarct, defined as a stroke or a new or enlarged silent cerebral infarct. RESULTS: A total of 196 children (mean age, 10 years) were randomly assigned to the observation or transfusion group and were followed for a median of 3 years. In the transfusion group, 6 of 99 children (6%) had an end-point event (1 had a stroke, and 5 had new or enlarged silent cerebral infarcts). In the observation group, 14 of 97 children (14%) had an end-point event (7 had strokes, and 7 had new or enlarged silent cerebral infarcts). The incidence of the primary end point in the transfusion and observation groups was 2.0 and 4.8 events, respectively, per 100 years at risk, corresponding to an incidence rate ratio of 0.41 (95% confidence interval, 0.12 to 0.99; P=0.04). CONCLUSIONS: Regular blood-transfusion therapy significantly reduced the incidence of the recurrence of cerebral infarct in children with sickle cell anemia. (Funded by the National Institute of Neurological Disorders and Stroke and others; Silent Cerebral Infarct Multi-Center Clinical Trial ClinicalTrials.gov number, NCT00072761, and Current Controlled Trials number, ISRCTN52713285.).


Asunto(s)
Anemia de Células Falciformes/terapia , Transfusión Sanguínea , Infarto Cerebral/prevención & control , Adolescente , Anemia de Células Falciformes/complicaciones , Infarto Cerebral/etiología , Niño , Preescolar , Femenino , Ferritinas/sangre , Hemoglobina Falciforme/análisis , Humanos , Inteligencia , Análisis de Intención de Tratar , Masculino , Prevención Secundaria , Método Simple Ciego , Reacción a la Transfusión
7.
Biochem Biophys Res Commun ; 487(3): 690-694, 2017 06 03.
Artículo en Inglés | MEDLINE | ID: mdl-28442345

RESUMEN

We have generated a humanized anti-cocaine monoclonal antibody (mAb), which is at an advanced stage of pre-clinical development. We report here in vitro binding affinity studies, and in vivo pharmacokinetic and efficacy studies of the recombinant mAb. The overall aim was to characterize the recombinant antibody from each of the three highest producing transfected clones and to select one to establish a master cell bank. In mAb pharmacokinetic studies, after injection with h2E2 (120 mg/kg iv) blood was collected from the tail tip of mice over 28 days. Antibody concentrations were quantified using ELISA. The h2E2 concentration as a function of time was fit using a two-compartment pharmacokinetic model. To test in vivo efficacy, mice were injected with h2E2 (120 mg/kg iv), then one hour later injected with an equimolar dose of cocaine. Blood and brain were collected 5 min after cocaine administration. Cocaine concentrations were quantified using LC/MS. The affinity of the antibody for cocaine was determined using a [3H] cocaine binding assay. All three antibodies had long elimination half-lives, 2-5 nM Kd for cocaine, and prevented cocaine's entry into the brain by sequestering it in the plasma. Pharmacokinetic and radioligand binding assays supported designation of the highest producing clone 85 as the master cell bank candidate. Overall, the recombinant h2E2 showed favorable binding properties, pharmacokinetics, and in vivo efficacy.


Asunto(s)
Anticuerpos Monoclonales/química , Anticuerpos Monoclonales/inmunología , Encéfalo/inmunología , Cocaína/química , Cocaína/inmunología , Bancos de Tejidos , Anticuerpos Monoclonales/genética , Clonación Molecular/métodos , Diseño de Fármacos , Tasa de Depuración Metabólica , Unión Proteica , Ingeniería de Proteínas/métodos , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunología , Distribución Tisular
8.
Environ Sci Technol ; 50(4): 1877-86, 2016 Feb 16.
Artículo en Inglés | MEDLINE | ID: mdl-26744776

RESUMEN

Reduction of suspended sediment (SS), total phosphorus (TP), and total nitrogen is an important focus for Chesapeake Bay watershed management. The Susquehanna River, the bay's largest tributary, has drawn attention because SS loads from behind Conowingo Dam (near the river's mouth) have been rising dramatically. To better understand these changes, we evaluated histories of concentration and loading (1986-2013) using data from sites above and below Conowingo Reservoir. First, observed concentration-discharge relationships show that SS and TP concentrations at the reservoir inlet have declined under most discharges in recent decades, but without corresponding declines at the outlet, implying recently diminished reservoir trapping. Second, best estimates of mass balance suggest decreasing net deposition of SS and TP in recent decades over a wide range of discharges, with cumulative mass generally dominated by the 75∼99.5th percentile of daily Conowingo discharges. Finally, stationary models that better accommodate effects of riverflow variability also support the conclusion of diminished trapping of SS and TP under a range of discharges that includes those well below the literature-reported scour threshold. Overall, these findings suggest that decreased net deposition of SS and TP has occurred at subscour levels of discharge, which has significant implications for the Chesapeake Bay ecosystem.


Asunto(s)
Bahías/química , Sedimentos Geológicos/química , Ríos/química , Calidad del Agua , Maryland , Nitrógeno/análisis , Pennsylvania , Fósforo/análisis
9.
Drug Metab Dispos ; 42(7): 1125-31, 2014 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-24733787

RESUMEN

The monoclonal antibody (mAb), h2E2, is a humanized version of the chimeric human/murine anti-cocaine mAb 2E2. The recombinant h2E2 protein was produced in vitro from a transfected mammalian cell line and retained high affinity (4 nM Kd) and specificity for cocaine over its inactive metabolites benzoylecgonine (BE) and ecgonine methyl ester. In rats, pharmacokinetic studies of h2E2 (120 mg/kg i.v.) showed a long terminal elimination half-life of 9.0 days and a low volume of distribution at steady state (Vdss) of 0.3 l/kg. Pretreatment with h2E2 produced a dramatic 8.8-fold increase in the area under the plasma cocaine concentration-time curve (AUC) and in brain a concomitant decrease of 68% of cocaine's AUC following an i.v. injection of an equimolar cocaine dose. Sequestration of cocaine in plasma by h2E2, shown via reduction of cocaine's Vdss, indicates potential clinical efficacy. Although the binding of cocaine to h2E2 in plasma should inhibit distribution and metabolism, the elimination of cocaine remained multicompartmental and was still rapidly eliminated from plasma despite the presence of h2E2. BE was the major cocaine metabolite, and brain BE concentrations were sixfold higher than in plasma, indicating that cocaine is normally metabolized in the brain. In the presence of h2E2, brain BE concentrations were decreased and plasma BE was increased, consistent with the observed h2E2-induced changes in cocaine disposition. The inhibition of cocaine distribution to the brain confirms the humanized mAb, h2E2, as a lead candidate for development as an immunotherapy for cocaine abuse.


Asunto(s)
Anticuerpos Monoclonales/inmunología , Encéfalo/metabolismo , Cocaína/inmunología , Animales , Células CHO , Cocaína/sangre , Cocaína/farmacocinética , Cricetinae , Cricetulus , Humanos , Masculino , Ratas , Ratas Sprague-Dawley
10.
Hum Psychopharmacol ; 29(6): 568-77, 2014 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-25330122

RESUMEN

OBJECTIVE: Aprepitant is a neurokinin 1 receptor antagonist approved for prevention of chemotherapy-induced and post-operative nausea and vomiting. Early studies demonstrated promising antidepressant activity as monotherapy, although this was unsupported by subsequent phase 3 trials. This phase 2 study evaluated whether aprepitant potentiated the antidepressant effects of paroxetine. METHODS: Outpatients with major depressive disorder were randomized to aprepitant 200 mg + paroxetine 20 mg, paroxetine + placebo, or aprepitant + placebo for 6 weeks. The primary endpoint was change in HAMD-17 total score. Secondary/exploratory endpoints included changes in HAMA, CGI-S, CGI-I, and HAMD Item-1 scores at week 6. RESULTS: A total of 79, 78, and 79 patients received aprepitant + paroxetine, paroxetine + placebo, and aprepitant + placebo, respectively. At week 6, mean changes in HAMD-17 were -11.0 (95% confidence interval [CI]: -12.7, -9.4), -11.7 (95% CI: -13.3, -10.0), and -9.5 (95% CI: -10.9, -8.1), respectively. Pairwise comparisons of HAMD-17 change with combination therapy versus paroxetine alone demonstrated no significant difference (p = 0.567). Changes in CGI-S, CGI-I, and HAMD Item-1 scores were also comparable, although there was a greater reduction in anxiety (HAMA) with paroxetine alone than aprepitant + paroxetine (p = 0.045). Adverse events were generally more common with the combination than either monotherapy. CONCLUSION: Concomitant use of aprepitant + paroxetine for 6 weeks did not provide greater antidepressant benefit compared with paroxetine + placebo in patients with major depression.


Asunto(s)
Antidepresivos/uso terapéutico , Trastorno Depresivo Mayor/tratamiento farmacológico , Morfolinas/uso terapéutico , Antagonistas del Receptor de Neuroquinina-1/uso terapéutico , Paroxetina/uso terapéutico , Inhibidores Selectivos de la Recaptación de Serotonina/uso terapéutico , Adulto , Antidepresivos/efectos adversos , Antidepresivos/farmacocinética , Aprepitant , Método Doble Ciego , Quimioterapia Combinada , Femenino , Humanos , Masculino , Morfolinas/efectos adversos , Morfolinas/farmacocinética , Antagonistas del Receptor de Neuroquinina-1/efectos adversos , Antagonistas del Receptor de Neuroquinina-1/farmacocinética , Paroxetina/efectos adversos , Paroxetina/farmacocinética , Escalas de Valoración Psiquiátrica , Inhibidores Selectivos de la Recaptación de Serotonina/efectos adversos , Inhibidores Selectivos de la Recaptación de Serotonina/farmacocinética , Resultado del Tratamiento
11.
Sensors (Basel) ; 14(4): 7142-55, 2014 Apr 22.
Artículo en Inglés | MEDLINE | ID: mdl-24759114

RESUMEN

Turbidity is an internationally recognized criterion for assessing drinking water quality, because the colloidal particles in turbid water may harbor pathogens, chemically reduce oxidizing disinfectants, and hinder attempts to disinfect water with ultraviolet radiation. A turbidimeter is an electronic/optical instrument that assesses turbidity by measuring the scattering of light passing through a water sample containing such colloidal particles. Commercial turbidimeters cost hundreds or thousands of dollars, putting them beyond the reach of low-resource communities around the world. An affordable open-source turbidimeter based on a single light-to-frequency sensor was designed and constructed, and evaluated against a portable commercial turbidimeter. The final product, which builds on extensive published research, is intended to catalyze further developments in affordable water and sanitation monitoring.


Asunto(s)
Nefelometría y Turbidimetría/economía , Nefelometría y Turbidimetría/instrumentación , Calibración , Diseño de Equipo , Estándares de Referencia
12.
Artículo en Inglés | MEDLINE | ID: mdl-38944417

RESUMEN

While there is a large body of evidence indicating that sexual minority youth experience inequitably high rates of mental health problems (eg, depression, suicidality), we know little about how temporal changes in sexual attractions, identities and behaviour may impact mental health (and other) outcomes. In this essay, we review existing research regarding sexual fluidity and mental health among young adults in order to identify critical knowledge gaps with respect to an epidemiological understanding of the relationship between these factors. We describe three gaps that in turn inform a larger public health research agenda on this topic. First, there are a number of methodological challenges given that fluidity can occur over short or long periods of time and across multiple dimensions of sexual orientation (eg, attractions, identities and behaviour) with various patterns (eg, directionality of change). Tailored measures that accurately and inclusively reflect diversities of sexual fluidity trajectories are needed. Second, causal relationships between sexual fluidity and mental health remain uncertain and unquantified. Third, little is known about how features of context (eg, gender norms and political climate) influence youth experiences with sexual fluidity and mental health. Finally, we propose a set of recommendations to address these knowledge gaps to improve the quality of epidemiological research involving young people.

13.
Soc Sci Med ; 353: 117057, 2024 Jun 19.
Artículo en Inglés | MEDLINE | ID: mdl-38905923

RESUMEN

Children with experience of maltreatment, abuse or neglect have higher prevalence of poor mental health. In the United Kingdom, child protection services identify children at risk of significant harm on the Child Protection Register (CPR) and intervene to reduce risk. Prevalence and incidence of mental health service use among this population of children are not well understood. We analysed records from one Scottish Local Authority's CPR, linked to electronic health records for all children in the broader health board region aged 0-17 years. We described mental health service use among children with a CPR registration using measures of mental health prescribing and referrals to child and adolescent mental health services (CAMHS). We calculated age- and sex-specific incidence rates for comparison with the general population. Between 2012 and 2022, we found 1498 children with a CPR registration, with 69% successfully linked to their health records. 20% were registered before birth and median age at registration was 3 years. Incidence rates in all measures of mental health service use were higher in children with a CPR record across all ages (at outcome) and genders compared to the general population. The largest absolute difference was for boys aged 5-9 with a CPR record, who had 31.8 additional mental health prescriptions per 1000 person-years compared to the general population (50.4 vs. 18.6 prescriptions per 1000 person-years, IRR: 2.7). Girls aged 0-4 years with a CPR registration had the largest relative difference, with a rate of CAMHS referral 5.4 times higher than the general population (12.3 vs. 2.3 per 1000 person-years). Our reproducible record linkage of the CPR to health records reveals an increased risk of mental health service use during childhood. Our findings have relevance to public mental health surveillance, service prioritisation and wider policy aiming to reduce childhood exposure to risk of harm.

14.
Environ Sci Technol ; 47(24): 14034-43, 2013 Dec 17.
Artículo en Inglés | MEDLINE | ID: mdl-24251816

RESUMEN

This paper provides results from studies of the transport of oxidized multi-walled carbon nanotubes (O-MWCNTs) of varying surface oxygen concentrations under a range of aquatic conditions and through uniform silica glass bead media. In the presence of Na(+), the required ionic strength (IS) for maximum particle attachment efficiency (i.e., the critical deposition concentration, or CDC) increased as the surface oxygen concentration of the O-MWCNTs or pH increased, following qualitative tenets of theories based on electrostatic interactions. In the presence of Ca(2+), CDC values were lower than those with Na(+) present, but were no longer sensitive to surface oxygen content, suggesting that Ca(2+) impacts the interactions between O-MWCNTs and glass beads by mechanisms other than electrostatic alone. The presence of Suwannee River natural organic matter (SRNOM) decreased the attachment efficiency of O-MWCNTs in the presence of either Na(+) or Ca(2+), but with more pronounced effects when Na(+) was present. Nevertheless, low concentrations of SRNOM (<4 mg/L of dissolved organic carbon) were sufficient to mobilize all O-MWCNTs studied at CaCl2 concentrations as high as 10 mM. Overall, this study reveals that NOM content, pH, and cation type show more importance than surface chemistry in affecting O-MWCNTs deposition during transport through silica-based porous media.


Asunto(s)
Nanotubos de Carbono/química , Compuestos Orgánicos/química , Dióxido de Silicio/química , Agua/química , Concentración de Iones de Hidrógeno , Concentración Osmolar , Oxidación-Reducción , Oxígeno/química , Porosidad , Propiedades de Superficie , Contaminantes Químicos del Agua/química
15.
Environ Sci Technol ; 46(23): 12839-47, 2012 Dec 04.
Artículo en Inglés | MEDLINE | ID: mdl-23145852

RESUMEN

The sorption properties of natural organic matter (NOM) with oxidized multiwalled carbon nanotubes (O-MWCNTs) in simple electrolytes has been studied, as well as the effect that NOM concentration, pH, and O-MWCNT surface chemistry have on CNT stability under environmentally relevant conditions. As O-MWCNT oxygen content increased, NOM sorption decreased in simple electrolytes for a common set of solution conditions. For each O-MWCNT, NOM sorption increased with increasing ionic strength and decreasing pH, although the sensitivity of NOM sorption to these water quality parameters increased as the O-MWCNT oxygen content increased. Collectively, these observations indicate that NOM sorption by O-MWCNTs is determined by favorable hydrophobic π-π interactions that are moderated by repulsive electrostatic forces between negatively charged carboxylic acid functional groups on the O-MWCNTs and NOM. Stability studies conducted in artificial groundwater revealed that CNT stability is influenced by both the NOM concentration and pH, but stability was largely independent of the O-MWCNT oxygen concentration. These findings contrast with the marked effect that surface oxygen has on CNT stability in simple electrolytes. Electrophoretic mobility measurements revealed that the stabilizing effects of adsorbed NOM are due to the introduction of steric repulsion between NOM-coated CNTs, rather than from changes to surface charge.


Asunto(s)
Sustancias Húmicas/análisis , Nanotubos de Carbono/química , Oxígeno/química , Adsorción , Electrólitos/química , Concentración Osmolar , Oxidación-Reducción , Propiedades de Superficie
17.
Langmuir ; 26(2): 967-81, 2010 Jan 19.
Artículo en Inglés | MEDLINE | ID: mdl-19894751

RESUMEN

Exposure of multiwalled carbon nanotubes (MWCNTs) to oxidizing acids and other oxidants introduces oxygen-containing functional groups such as hydroxyl, carboxyl, and carbonyl groups onto the surface. This research evaluated how changes in oxygen concentration and distribution of oxygen-containing functional groups influenced the sorption of aqueous zinc and cadmium on MWCNTs. Sorption results with natural char, activated carbon, and a suite of MWCNTs (of varying surface oxygen content) were obtained. Results confirmed that surface oxygen enhances the sorption of both Zn[II] and Cd[II] from aqueous solution. Although Zn[II] sorbed more strongly than Cd[II] for all materials studied, surface oxidation had more effect on the sorption of Cd[II] than of Zn[II]. Additional sorption experiments with Zn[II] and 16 MWCNTs of varying surface oxidation level and functional group distribution revealed the relative contributions of different types of surface sites to sorption. Sorption isotherms were fit using a two-site Langmuir adsorption model that incorporated the independent characterization of functional group distribution. Results showed that carboxyl-carbon sites were over 20 times more energetic for zinc sorption than unoxidized carbon (graphenic-carbon) sites, though both site types are important contributors to sorption.

18.
Proc Math Phys Eng Sci ; 476(2238): 20200077, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32831591

RESUMEN

Recent reconstructions of total solar irradiance (TSI) postulate that quiet-Sun variations could give significant changes to the solar power input to Earth's climate (radiative climate forcings of 0.7-1.1 W m-2 over 1700-2019) arising from changes in quiet-Sun magnetic fields that have not, as yet, been observed. Reconstructions without such changes yield solar forcings that are smaller by a factor of more than 10. We study the quiet-Sun TSI since 1995 for three reasons: (i) this interval shows rapid decay in average solar activity following the grand solar maximum in 1985 (such that activity in 2019 was broadly equivalent to that in 1900); (ii) there is improved consensus between TSI observations; and (iii) it contains the first modelling of TSI that is independent of the observations. Our analysis shows that the most likely upward drift in quiet-Sun radiative forcing since 1700 is between +0.07 and -0.13 W m-2. Hence, we cannot yet discriminate between the quiet-Sun TSI being enhanced or reduced during the Maunder and Dalton sunspot minima, although there is a growing consensus from the combinations of models and observations that it was slightly enhanced. We present reconstructions that add quiet-Sun TSI and its uncertainty to models that reconstruct the effects of sunspots and faculae.

19.
J Pharmacol Exp Ther ; 328(3): 873-81, 2009 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-19088302

RESUMEN

The predominantly human sequence anti-cocaine monoclonal antibody (mAb), 2E2, has high affinity and specificity for cocaine and antagonizes cocaine distribution to the brain in mice. To determine whether 2E2 can alter the self-administration of cocaine in rats, both cocaine-induced reinstatement (priming) of self-administration, and the rates of cocaine consumption were assessed during daily sessions. After self-administration training, the rats' cocaine priming threshold values were stable over a 2-week baseline period. Furthermore, the rates of cocaine consumption at unit doses of 0.3 and 3.0 micromol/kg were steady within sessions and stable between sessions. Then, 2E2 (120 mg/kg i.v.) or an equivalent dose of nonspecific human polyclonal IgG (control) was infused and daily sessions continued. 2E2 produced an initial, approximately 3-fold, increase in the cocaine priming threshold that declined toward baseline values over the subsequent 3 weeks, with an effect t((1/2)) of approximately 4 days. In contrast to the substantial increase in the cocaine priming threshold, 2E2 produced only modest dose-dependent increases (42 and 18%) in the cocaine consumption rates, and these also gradually declined toward baseline values. There was no significant effect of the control IgG on the priming threshold or rates of consumption of cocaine. After infusion, antibody blood concentrations declined over time, and a two-compartment pharmacokinetic model generated values for the distribution and elimination half-lives of 0.5 and 11.6 days for 2E2 and 0.4 and 6.0 days for control IgG. 2E2 had a long-lasting effect on cocaine-induced priming, which may predict its efficacy as an immunotherapy for cocaine abuse.


Asunto(s)
Anticuerpos Monoclonales/uso terapéutico , Cocaína/inmunología , Cocaína/farmacología , Proteínas Mutantes Quiméricas/farmacología , Animales , Anticuerpos/administración & dosificación , Anticuerpos/sangre , Anticuerpos/uso terapéutico , Anticuerpos Monoclonales/administración & dosificación , Anticuerpos Monoclonales/sangre , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Cocaína/administración & dosificación , Cocaína/farmacocinética , Trastornos Relacionados con Cocaína/inmunología , Semivida , Humanos , Inmunoglobulina G/farmacología , Inmunoterapia/métodos , Masculino , Ratones , Ratas , Ratas Sprague-Dawley , Autoadministración , Distribución Tisular/efectos de los fármacos
20.
J Digit Imaging ; 22(3): 326-43, 2009 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-18398653

RESUMEN

The Silent Cerebral Infarct Multicenter Transfusion (SIT) Trial is a multi-institutional intervention trial in which children with silent cerebral infarcts are randomized to receive either blood transfusion therapy or observation (standard care) for 36 months. The SIT Trial is scheduled to enroll approximately 1,880 children with sickle cell disease from 29 clinical sites in the United States, Canada, UK, and France. Each child undergoes a screening magnetic resonance imaging (MRI) of the brain to detect the presence of silent cerebral infarct-like lesions, a pre-randomization (baseline) MRI and exit MRI to determine if there are new or enlarged cerebral infarcts, using a designated, prospective imaging protocol. The objective of this manuscript is to describe the innovative method used to process and adjudicate imaging studies for an international trial with a primary endpoint that includes neuroimaging. Institution investigators at each site were provided with computer hardware and software for transmission of MRI images that allow them to strip the scans of all personal information and add unique study identifiers. Three neuroradiologists at separate academic centers review MRI studies and determine the presence or absence of silent cerebral infarct-like lesions. Their findings are subsequently placed on web-based case report forms and sent to the Statistical Coordinating Center. The average time from imaging center receipt of the MRI study to the radiology committee report back to the local site is less than two working days. This novel strategy was designed to maximize efficiency and minimize cost of a complex large multicenter trial that depends heavily on neuroimaging for entry criteria and assessment for the primary outcome measures. The technology, process, and expertise used in the SIT Trial can be adapted to virtually any clinical research trial with digital imaging requirements.


Asunto(s)
Anemia de Células Falciformes/complicaciones , Infarto Cerebral/patología , Procesamiento de Imagen Asistido por Computador/métodos , Imagen por Resonancia Magnética/métodos , Tamizaje Masivo/métodos , Sistemas de Información Radiológica , Anemia de Células Falciformes/patología , Encéfalo/patología , Canadá , Infarto Cerebral/etiología , Niño , Francia , Humanos , Variaciones Dependientes del Observador , Programas Informáticos , Reino Unido , Estados Unidos
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