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1.
PLoS One ; 13(7): e0200354, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29995947

RESUMO

BACKGROUND AND OBJECTIVES: Exercise capacity is reduced in chronic kidney failure (CKF). Intra-dialytic cycling is beneficial, but comorbidity and fatigue can prevent this type of training. Low-frequency electrical muscle stimulation (LF-EMS) of the quadriceps and hamstrings elicits a cardiovascular training stimulus and may be a suitable alternative. The main objectives of this trial were to assess the feasibility and efficacy of intra-dialytic LF-EMS vs. cycling. DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS: Assessor blind, parallel group, randomized controlled pilot study with sixty-four stable patients on maintenance hemodialysis. Participants were randomized to 10 weeks of 1) intra-dialytic cycling, 2) intra-dialytic LF-EMS, or 3) non-exercise control. Exercise was performed for up to one hour three times per week. Cycling workload was set at 40-60% oxygen uptake (VO2) reserve, and LF-EMS at maximum tolerable intensity. The control group did not complete any intra-dialytic exercise. Feasibility of intra-dialytic LF-EMS and cycling was the primary outcome, assessed by monitoring recruitment, retention and tolerability. At baseline and 10 weeks, secondary outcomes including cardio-respiratory reserve, muscle strength, and cardio-arterial structure and function were assessed. RESULTS: Fifty-one (of 64 randomized) participants completed the study (LF-EMS = 17 [77%], cycling = 16 [80%], control = 18 [82%]). Intra-dialytic LF-EMS and cycling were feasible and well tolerated (9% and 5% intolerance respectively, P = 0.9). At 10-weeks, cardio-respiratory reserve (VO2 peak) (Difference vs. control: LF-EMS +2.0 [95% CI, 0.3 to 3.7] ml.kg-1.min-1, P = 0.02, and cycling +3.0 [95% CI, 1.2 to 4.7] ml.kg-1.min-1, P = 0.001) and leg strength (Difference vs. control: LF-EMS, +94 [95% CI, 35.6 to 152.3] N, P = 0.002 and cycling, +65.1 [95% CI, 6.4 to 123.8] N, P = 0.002) were improved. Arterial structure and function were unaffected. CONCLUSIONS: Ten weeks of intra-dialytic LF-EMS or cycling improved cardio-respiratory reserve and muscular strength. For patients who are unable or unwilling to cycle during dialysis, LF-EMS is a feasible alternative.

2.
Clin Biochem ; 56: 109-112, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29684369

RESUMO

OBJECTIVES: Alpha-fetoprotein (AFP) measurement in pericardial, peritoneal (ascites), and pleural fluids is sometimes requested by clinicians as supportive evidence in the evaluation of suspected malignancy. As commercially available, Food and Drug Administration (FDA)-cleared AFP assays are not validated for these fluid types, laboratories must complete additional validation studies to comply with regulatory requirements for body fluid testing. The objective of this study was therefore to conduct a matrix evaluation for these body fluid types using the Beckman Access AFP assay on the UniCel DxI 800 immunoassay system. DESIGN AND METHODS: Using an Institutional Review Board (IRB) approved protocol, previously collected pericardial fluid, peritoneal fluid, pleural fluid, and serum specimens were de-identified and frozen at -20 °C prior to matrix evaluation experiments. Spiked recovery, mixed recovery/linearity, and precision studies were conducted. RESULTS: In spiked and mixed recovery studies, the average percent (%) recovery was within predefined acceptable limits (±15%) for all three body fluids. Linearity was observed over the analytical measurement range (AMR) for all three body fluids (slope, intercept, systematic error): pericardial 0.988, -0.1, 6.1%; peritoneal 0.986, 0.0, 4.1%; and pleural 1.016, 0.0, 1.6%. Imprecision was ≤6.0% CV for all three body fluids at both high and low AFP concentrations. CONCLUSIONS: Matrix interference with AFP testing was not observed for pericardial, peritoneal, or pleural fluids on the Beckman UniCel DxI 800 system.


Assuntos
Líquido Ascítico/metabolismo , Automação Laboratorial/instrumentação , Líquido Pericárdico/metabolismo , Derrame Pleural/metabolismo , alfa-Fetoproteínas/metabolismo , Humanos , Imunoensaio , Derrame Pleural/sangue , Reprodutibilidade dos Testes , alfa-Fetoproteínas/análise
3.
Ann Rheum Dis ; 77(4): 612-619, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29358286

RESUMO

OBJECTIVES: To characterise the clinical features, immune manifestations and molecular mechanisms in a recently described autoinflammatory disease caused by mutations in TRNT1, a tRNA processing enzyme, and to explore the use of cytokine inhibitors in suppressing the inflammatory phenotype. METHODS: We studied nine patients with biallelic mutations in TRNT1 and the syndrome of congenital sideroblastic anaemia with immunodeficiency, fevers and developmental delay (SIFD). Genetic studies included whole exome sequencing (WES) and candidate gene screening. Patients' primary cells were used for deep RNA and tRNA sequencing, cytokine profiling, immunophenotyping, immunoblotting and electron microscopy (EM). RESULTS: We identified eight mutations in these nine patients, three of which have not been previously associated with SIFD. Three patients died in early childhood. Inflammatory cytokines, mainly interleukin (IL)-6, interferon gamma (IFN-γ) and IFN-induced cytokines were elevated in the serum, whereas tumour necrosis factor (TNF) and IL-1ß were present in tissue biopsies of patients with active inflammatory disease. Deep tRNA sequencing of patients' fibroblasts showed significant deficiency of mature cytosolic tRNAs. EM of bone marrow and skin biopsy samples revealed striking abnormalities across all cell types and a mix of necrotic and normal-appearing cells. By immunoprecipitation, we found evidence for dysregulation in protein clearance pathways. In 4/4 patients, treatment with a TNF inhibitor suppressed inflammation, reduced the need for blood transfusions and improved growth. CONCLUSIONS: Mutations of TRNT1 lead to a severe and often fatal syndrome, linking protein homeostasis and autoinflammation. Molecular diagnosis in early life will be crucial for initiating anti-TNF therapy, which might prevent some of the severe disease consequences.

4.
J Anal Psychol ; 63(1): 3-5, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29314023
5.
Brain Res ; 1679: 101-108, 2018 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-29191772

RESUMO

Animal models of tinnitus are essential for determining the underlying mechanisms and testing pharmacotherapies. However, there is doubt over the validity of current behavioural methods for detecting tinnitus. Here, we applied a stimulus paradigm widely used in a behavioural test (gap-induced inhibition of the acoustic startle reflex GPIAS) whilst recording from the auditory cortex, and showed neural response changes that mirror those found in the behavioural tests. We implanted guinea pigs (GPs) with electrocorticographic (ECoG) arrays and recorded baseline auditory cortical responses to a startling stimulus. When a gap was inserted in otherwise continuous background noise prior to the startling stimulus, there was a clear reduction in the subsequent evoked response (termed gap-induced reductions in evoked potentials; GIREP), suggestive of a neural analogue of the GPIAS test. We then unilaterally exposed guinea pigs to narrowband noise (left ear; 8-10 kHz; 1 h) at one of two different sound levels - either 105 dB SPL or 120 dB SPL - and recorded the same responses seven-to-ten weeks following the noise exposure. Significant deficits in GIREP were observed for all areas of the auditory cortex (AC) in the 120 dB-exposed GPs, but not in the 105 dB-exposed GPs. These deficits could not simply be accounted for by changes in response amplitudes. Furthermore, in the contralateral (right) caudal AC we observed a significant increase in evoked potential amplitudes across narrowband background frequencies in both 105 dB and 120 dB-exposed GPs. Taken in the context of the large body of literature that has used the behavioural test as a demonstration of the presence of tinnitus, these results are suggestive of objective neural correlates of the presence of noise-induced tinnitus and hyperacusis.


Assuntos
Córtex Auditivo/fisiopatologia , Potenciais Evocados Auditivos/fisiologia , Reflexo de Sobressalto/fisiologia , Zumbido/patologia , Estimulação Acústica , Análise de Variância , Animais , Modelos Animais de Doenças , Eletrocardiografia , Feminino , Lateralidade Funcional , Cobaias , Masculino , Ruído , Psicoacústica
6.
Hear Res ; 356: 51-62, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-29108871

RESUMO

Cannabinoids have been suggested as a therapeutic target for a variety of brain disorders. Despite the presence of their receptors throughout the auditory system, little is known about how cannabinoids affect auditory function. We sought to determine whether administration of arachidonyl-2'-chloroethylamide (ACEA), a highly-selective CB1 agonist, could attenuate a variety of auditory effects caused by prior administration of salicylate, and potentially treat tinnitus. We recorded cortical resting-state activity, auditory-evoked cortical activity and auditory brainstem responses (ABRs), from chronically-implanted awake guinea pigs, before and after salicylate + ACEA. Salicylate-induced reductions in click-evoked ABR amplitudes were smaller in the presence of ACEA, suggesting that the ototoxic effects of salicylate were less severe. ACEA also abolished salicylate-induced changes in cortical alpha band (6-10 Hz) oscillatory activity. However, salicylate-induced increases in cortical evoked activity (suggestive of the presence of hyperacusis) were still present with salicylate + ACEA. ACEA administered alone did not induce significant changes in either ABR amplitudes or oscillatory activity, but did increase cortical evoked potentials. Furthermore, in two separate groups of non-implanted animals, we found no evidence that ACEA could reverse behavioural identification of salicylate- or noise-induced tinnitus. Together, these data suggest that while ACEA may be potentially otoprotective, selective CB1 agonists are not effective in diminishing the presence of tinnitus or hyperacusis.


Assuntos
Ácidos Araquidônicos/farmacologia , Córtex Auditivo/efeitos dos fármacos , Agonistas de Receptores de Canabinoides/farmacologia , Hiperacusia/prevenção & controle , Receptor CB1 de Canabinoide/agonistas , Ácido Salicílico , Zumbido/prevenção & controle , Estimulação Acústica , Ritmo alfa/efeitos dos fármacos , Animais , Córtex Auditivo/metabolismo , Córtex Auditivo/fisiopatologia , Comportamento Animal/efeitos dos fármacos , Citoproteção , Modelos Animais de Doenças , Eletrocorticografia , Potenciais Evocados Auditivos/efeitos dos fármacos , Potenciais Evocados Auditivos do Tronco Encefálico/efeitos dos fármacos , Feminino , Cobaias , Hiperacusia/induzido quimicamente , Hiperacusia/metabolismo , Hiperacusia/fisiopatologia , Masculino , Ruído , Tempo de Reação/efeitos dos fármacos , Receptor CB1 de Canabinoide/metabolismo , Transdução de Sinais/efeitos dos fármacos , Fatores de Tempo , Zumbido/induzido quimicamente , Zumbido/metabolismo , Zumbido/fisiopatologia
7.
Med Sci Sports Exerc ; 49(10): 1980-1986, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28489686

RESUMO

PURPOSE: The aim of this study was to describe the relationship between body size and oxygen uptake efficiency slope (OUES) in pediatric patients with cystic fibrosis (CF) and healthy controls (CON), to identify appropriate scaling procedures to adjust the influence of body size upon OUES. METHODS: The OUES was derived using maximal and submaximal points from cardiopulmonary exercise testing in 72 children (36 CF and 36 CON). OUES was subsequently scaled for stature, body mass (BM), and body surface area (BSA) using ratio-standard (Y/X) and allometric (Y/X) methods. Pearson's correlation coefficients were used to determine the relationship between body size and OUES. RESULTS: When scaled using the ratio-standard method, OUES had a significant positive relationship with stature (r = 0.54, P < 0.001) and BSA (r = 0.25, P = 0.031) and significant negative relationship with BM (r = -0.38, P = 0.016) in the CF group. Combined allometric exponents (b) for CF and CON were stature 3.00, BM 0.86, and BSA 1.40. A significant negative correlation was found between OUES and stature in the CF group when scaled allometrically (r = -0.37, P = 0.027). Nonsignificant (P > 0.05) correlations for the whole group were found between OUES and allometrically scaled BM (CF r = -0.25, CON, r = 0.15) and BSA (CF r = -0.27, CON r = 0.13). CONCLUSIONS: Only allometric scaling of either BM or BSA, and not ratio-standard scaling, successfully eliminates the influence of body size upon OUES. Therefore, this enables a more direct comparison of the OUES between patients with CF and healthy controls.


Assuntos
Tamanho Corporal/fisiologia , Fibrose Cística/fisiopatologia , Oxigênio/fisiologia , Respiração , Estatura , Índice de Massa Corporal , Superfície Corporal , Teste de Esforço , Humanos , Consumo de Oxigênio/fisiologia
8.
PLoS One ; 12(1): e0170798, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28141869

RESUMO

Advanced lung cancer has poor survival with few therapies. EGFR tyrosine kinase inhibitors (TKIs) have high response rates in patients with activating EGFR mutations, but acquired resistance is inevitable. Acquisition of the EGFR T790M mutation causes over 50% of resistance; MET amplification is also common. Preclinical data suggest synergy between MET and EGFR inhibitors. We hypothesized that EGFR-MET dimerization determines response to MET inhibition, depending on EGFR mutation status, independently of MET copy number. We tested this hypothesis by generating isogenic cell lines from NCI-H1975 cells, which co-express L858R and T790M EGFR mutations, namely H1975L858R/T790M (EGFR TKI resistant); H1975L858R (sensitized) and H1975WT (wild-type). We assessed cell proliferation in vitro and tumor growth/stroma formation in derived xenograft models in response to a MET TKI (SGX523) and correlated with EGFR-MET dimerization assessed by Förster Resonance Energy Transfer (FRET). SGX523 significantly reduced H1975L858R/T790M cell proliferation, xenograft tumor growth and decreased ERK phosphorylation. The same was not seen in H1975L858R or H1975WT cells. SGX523 only reduced stroma formation in H1975L858R. SGX523 reduced EGFR-MET dimerization in H1975L858R/T790M but induced dimer formation in H1975L858R with no effect in H1975WT. Our data suggests that MET inhibition by SGX523 and EGFR-MET heterodimerisation are determined by EGFR genotype. As tumor behaviour is modulated by this interaction, this could determine treatment efficacy.


Assuntos
Adenocarcinoma/genética , Receptores ErbB/genética , Neoplasias Pulmonares/genética , Mutação/genética , Inibidores de Proteínas Quinases/farmacologia , Multimerização Proteica , Proteínas Proto-Oncogênicas c-met/antagonistas & inibidores , Adenocarcinoma/enzimologia , Adenocarcinoma/patologia , Adenocarcinoma de Pulmão , Animais , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Proteína-Tirosina Quinases de Adesão Focal/metabolismo , Células HEK293 , Humanos , Neoplasias Pulmonares/enzimologia , Neoplasias Pulmonares/patologia , Camundongos Endogâmicos BALB C , Camundongos Nus , Fosforilação/efeitos dos fármacos , Ligação Proteica/efeitos dos fármacos , Multimerização Proteica/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteínas Proto-Oncogênicas c-met/metabolismo , Reprodutibilidade dos Testes
9.
Br J Haematol ; 176(2): 300-308, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27766637

RESUMO

'Paradoxical' embolization via intracardiac or intrapulmonary right-to-left shunts (RLS) is an established cause of stroke. Hypercoagulable states and increased right heart pressure, which both occur in sickle cell anaemia (SCA), predispose to paradoxical embolization. We hypothesized that children with SCA and overt stroke (SCA + stroke) have an increased prevalence of potential RLS. We performed contrasted transthoracic echocardiograms on 147 children (aged 2-19 years) with SCA + stroke) mean age 12·7 ± 4·8 years, 54·4% male) and a control group without SCA or stroke (n = 123; mean age 12·1 ± 4·9 years, 53·3% male). RLS was defined as any potential RLS detected by any method, including intrapulmonary shunting. Echocardiograms were masked and adjudicated centrally. The prevalence of potential RLS was significantly higher in the SCA+stroke group than controls (45·6% vs. 23·6%, P < 0·001). The odds ratio for potential RLS in the SCA + stroke group was 2·7 (95% confidence interval: 1·6-4·6) vs controls. In post hoc analyses, the SCA + stroke group had a higher prevalence of intrapulmonary (23·8% vs. 5·7%, P < 0·001) but not intracardiac shunting (21·8% vs. 18·7%, P = 0·533). SCA patients with potential RLS were more likely to report headache at stroke onset than those without. Intrapulmonary and intracardiac shunting may be an overlooked, independent and potentially modifiable risk factor for stroke in SCA.


Assuntos
Anemia Falciforme/complicações , Defeitos dos Septos Cardíacos/diagnóstico por imagem , Acidente Vascular Cerebral/etiologia , Adolescente , Anemia Falciforme/epidemiologia , Criança , Pré-Escolar , Ecocardiografia , Embolia Paradoxal/etiologia , Feminino , Cefaleia/etiologia , Defeitos dos Septos Cardíacos/complicações , Humanos , Masculino , Prevalência , Fatores de Risco , Adulto Jovem
10.
J Anal Psychol ; 61(5): 565-566, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27763677
11.
J Anal Psychol ; 61(3): 350-61, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-27192368
13.
Am J Hematol ; 91(2): 238-42, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26615793

RESUMO

Although hemoglobin SC (HbSC) disease is usually considered less severe than sickle cell anemia (SCA), which includes HbSS and HbS/ß(0) -thalassemia genotypes, many patients with HbSC experience severe disease complications, including vaso-occlusive pain, acute chest syndrome, avascular necrosis, retinopathy, and poor quality of life. Fully 20 years after the clinical and laboratory efficacy of hydroxyurea was proven in adult SCA patients, the safety and utility of hydroxyurea treatment for HbSC patients remain unclear. Recent NHLBI evidence-based guidelines highlight this as a critical knowledge gap, noting HbSC accounts for ∼30% of sickle cell patients within the United States. To date, only 5 publications have reported short-term, incomplete, or conflicting laboratory and clinical outcomes of hydroxyurea treatment in a total of 71 adults and children with HbSC. We now report on a cohort of 133 adult and pediatric HbSC patients who received hydroxyurea, typically for recurrent vaso-occlusive pain. Hydroxyurea treatment was associated with a stable hemoglobin concentration; increased fetal hemoglobin (HbF) and mean corpuscular volume (MCV); and reduced white blood cell count (WBC), absolute neutrophil count (ANC), and absolute reticulocyte count (ARC). Reversible cytopenias occurred in 22% of patients, primarily neutropenia and thrombocytopenia. Painful events were reduced with hydroxyurea, more in patients >15 years old. These multicenter data support the safety and potentially salutary effects of hydroxyurea treatment for HbSC disease; however, a multicenter, placebo-controlled, Phase 3 clinical trial is needed to determine if hydroxyurea therapy has efficacy for patients with HbSC disease.


Assuntos
Anemia Falciforme/tratamento farmacológico , Antidrepanocíticos/uso terapêutico , Hidroxiureia/uso terapêutico , Adolescente , Anemia Falciforme/genética , Antidrepanocíticos/administração & dosagem , Antidrepanocíticos/efeitos adversos , Criança , Feminino , Humanos , Hidroxiureia/administração & dosagem , Hidroxiureia/efeitos adversos , Masculino , Estudos Retrospectivos , Resultado do Tratamento
14.
Lancet ; 387(10019): 661-70, 2016 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-26670617

RESUMO

BACKGROUND: For children with sickle cell anaemia and high transcranial doppler (TCD) flow velocities, regular blood transfusions can effectively prevent primary stroke, but must be continued indefinitely. The efficacy of hydroxycarbamide (hydroxyurea) in this setting is unknown; we performed the TWiTCH trial to compare hydroxyurea with standard transfusions. METHODS: TWiTCH was a multicentre, phase 3, randomised, open-label, non-inferiority trial done at 26 paediatric hospitals and health centres in the USA and Canada. We enrolled children with sickle cell anaemia who were aged 4-16 years and had abnormal TCD flow velocities (≥ 200 cm/s) but no severe vasculopathy. After screening, eligible participants were randomly assigned 1:1 to continue standard transfusions (standard group) or hydroxycarbamide (alternative group). Randomisation was done at a central site, stratified by site with a block size of four, and an adaptive randomisation scheme was used to balance the covariates of baseline age and TCD velocity. The study was open-label, but TCD examinations were read centrally by observers masked to treatment assignment and previous TCD results. Participants assigned to standard treatment continued to receive monthly transfusions to maintain 30% sickle haemoglobin or lower, while those assigned to the alternative treatment started oral hydroxycarbamide at 20 mg/kg per day, which was escalated to each participant's maximum tolerated dose. The treatment period lasted 24 months from randomisation. The primary study endpoint was the 24 month TCD velocity calculated from a general linear mixed model, with the non-inferiority margin set at 15 cm/s. The primary analysis was done in the intention-to-treat population and safety was assessed in all patients who received at least one dose of assigned treatment. This study is registered with ClinicalTrials.gov, number NCT01425307. FINDINGS: Between Sept 20, 2011, and April 17, 2013, 159 patients consented and enrolled in TWiTCH. 121 participants passed screening and were then randomly assigned to treatment (61 to transfusions and 60 to hydroxycarbamide). At the first scheduled interim analysis, non-inferiority was shown and the sponsor terminated the study. Final model-based TCD velocities were 143 cm/s (95% CI 140-146) in children who received standard transfusions and 138 cm/s (135-142) in those who received hydroxycarbamide, with a difference of 4·54 (0·10-8·98). Non-inferiority (p=8·82 × 10(-16)) and post-hoc superiority (p=0·023) were met. Of 29 new neurological events adjudicated centrally by masked reviewers, no strokes were identified, but three transient ischaemic attacks occurred in each group. Magnetic resonance brain imaging and angiography (MRI and MRA) at exit showed no new cerebral infarcts in either treatment group, but worsened vasculopathy in one participant who received standard transfusions. 23 severe adverse events in nine (15%) patients were reported for hydroxycarbamide and ten serious adverse events in six (10%) patients were reported for standard transfusions. The most common serious adverse event in both groups was vaso-occlusive pain (11 events in five [8%] patients with hydroxycarbamide and three events in one [2%] patient for transfusions). INTERPRETATION: For high-risk children with sickle cell anaemia and abnormal TCD velocities who have received at least 1 year of transfusions, and have no MRA-defined severe vasculopathy, hydroxycarbamide treatment can substitute for chronic transfusions to maintain TCD velocities and help to prevent primary stroke. FUNDING: National Heart, Lung, and Blood Institute, National Institutes of Health.


Assuntos
Anemia Falciforme/tratamento farmacológico , Antidrepanocíticos/uso terapêutico , Transfusão de Sangue/métodos , Hidroxiureia/uso terapêutico , Adolescente , Anemia Falciforme/fisiopatologia , Velocidade do Fluxo Sanguíneo , Circulação Cerebrovascular/fisiologia , Criança , Pré-Escolar , Terapia Combinada , Substituição de Medicamentos , Feminino , Humanos , Masculino , Acidente Vascular Cerebral/etiologia , Resultado do Tratamento , Ultrassonografia Doppler Transcraniana
15.
J Anal Psychol ; 60(5): 597-600, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26499294
16.
J Vis Exp ; (101): e52900, 2015 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-26274555

RESUMO

Reducing the scale of etched nanostructures below the 10 nm range eventually will require an atomic scale understanding of the entire fabrication process being used in order to maintain exquisite control over both feature size and feature density. Here, we demonstrate a method for tracking atomically resolved and controlled structures from initial template definition through final nanostructure metrology, opening up a pathway for top-down atomic control over nanofabrication. Hydrogen depassivation lithography is the first step of the nanoscale fabrication process followed by selective atomic layer deposition of up to 2.8 nm of titania to make a nanoscale etch mask. Contrast with the background is shown, indicating different mechanisms for growth on the desired patterns and on the H passivated background. The patterns are then transferred into the bulk using reactive ion etching to form 20 nm tall nanostructures with linewidths down to ~6 nm. To illustrate the limitations of this process, arrays of holes and lines are fabricated. The various nanofabrication process steps are performed at disparate locations, so process integration is discussed. Related issues are discussed including using fiducial marks for finding nanostructures on a macroscopic sample and protecting the chemically reactive patterned Si(100)-H surface against degradation due to atmospheric exposure.


Assuntos
Nanoestruturas/química , Nanotecnologia/métodos , Microscopia de Tunelamento/métodos , Impressão
17.
Am J Hematol ; 90(9): 806-10, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26087998

RESUMO

Noninvasive, quantitative, and accurate assessment of liver iron concentration (LIC) by MRI is useful for patients receiving transfusions, but R2 and R2* MRI techniques have not been systematically compared in sickle cell anemia (SCA). We report baseline LIC results from the TWiTCH trial, which compares hydroxyurea with blood transfusion treatment for primary stroke prophylaxis assessed by transcranial Doppler sonography in pediatric SCA patients. Liver R2 was collected and processed using a FDA-approved commercial process (FerriScan®), while liver R2* quality control and processing were performed by a Core Laboratory blinded to clinical site and patient data. Baseline LIC studies using both MRI techniques were available for 120 participants. LICR2* and LICR2 results were highly correlated (r(2) = 0.93). A proportional bias of LIC(R2*)/LIC(R2), decreasing with average LIC, was observed. Systematic differences between LICR2* and LICR2 were also observed by MRI manufacturer. Importantly, LICR2* and LICR2 estimates had broad 95% limits of agreement with respect to each other. We recommend LICR2 and LICR2* not be used interchangeably in SCA patients to follow individual patient trends in iron burden.


Assuntos
Anemia Falciforme/terapia , Bioensaio/normas , Sobrecarga de Ferro/metabolismo , Ferro/análise , Fígado/química , Reação Transfusional , Adolescente , Anemia Falciforme/patologia , Antidrepanocíticos/uso terapêutico , Benzoatos/uso terapêutico , Criança , Pré-Escolar , Deferasirox , Desferroxamina/uso terapêutico , Feminino , Humanos , Hidroxiureia/uso terapêutico , Ferro/metabolismo , Quelantes de Ferro/uso terapêutico , Sobrecarga de Ferro/tratamento farmacológico , Sobrecarga de Ferro/etiologia , Sobrecarga de Ferro/patologia , Fígado/metabolismo , Imagem por Ressonância Magnética , Masculino , Acidente Vascular Cerebral/prevenção & controle , Triazóis/uso terapêutico , Ultrassonografia Doppler Transcraniana
18.
Clin Lab ; 61(3-4): 283-8, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25974994

RESUMO

BACKGROUND: Vitamin B12 (cobalamin) is a necessary cofactor in methionine and succinyl-CoA metabolism. Studies estimate the deficiency prevalence as high as 30% in the elderly population. Ten to thirty percent of circulating cobalamin is bound to transcobalamin (holotranscobalamin, holoTC) which can readily enter cells and is therefore considered the bioactive form. The objective of our study was to evaluate the analytical performance of a high-throughput, automated holoTC assay (ARCHITECT i2000(SR) Active-B12 (Holotranscobalamin)) and compare it to other available methods. METHODS: Manufacturer-specified limits of blank (LoB), detection (LoD), and quantitation (LoQ), imprecision, interference, and linearity were evaluated for the ARCHITECT HoloTC assay. Residual de-identified serum samples were used to compare the ARCHITECT HoloTC assay with the automated AxSYM Active-B12 (Holotranscobalamin) assay (Abbott Diagnostics) and the manual Active-B12 (Holotranscobalamin) Enzyme Immunoassay (EIA) (Axis-Shield Diagnostics, Dundee, Scotland, UK). RESULTS: Manufacturer's claims of LoB, LoD, LoQ, imprecision, interference, and linearity to the highest point tested (113.4 pmol/L) were verified for the ARCHITECT HoloTC assay. Method comparison of the ARCHITECT HoloTC to the AxSYM HoloTC produced the following Deming regression statistics: (ARCHITECT(HoloTc)) = 0.941 (AxSYM(HoloTC)) + 1.2 pmol/L, S(y/x) = 6.4, r = 0.947 (n = 98). Comparison to the Active-B12 EIA produced: (ARCHITECT(HoloTC)) = 1.105 (EIA(Active-B12)) - 6.8 pmol/L, S(y/x) = 11.0, r = 0.950 (n = 221). CONCLUSIONS: This assay performed acceptably for LoB, LoD, LoQ, imprecision, interference, linearity and method comparison to the predicate device (AxSYM). An additional comparison to a manual Active-B12 EIA method performed similarly, with minor exceptions. This study determined that the ARCHITECT HoloTC assay is suitable for routine clinical use, which provides a high-throughput alternative for automated testing of this emerging marker of cobalamin deficiency.


Assuntos
Ensaios de Triagem em Larga Escala/métodos , Deficiência de Vitamina B 12/sangue , Acil Coenzima A/química , Automação , Biomarcadores/sangue , Humanos , Técnicas Imunoenzimáticas/métodos , Limite de Detecção , Metionina/química , Reprodutibilidade dos Testes , Transcobalaminas/química , Complexo Vitamínico B/sangue
19.
Clin Biochem ; 48(13-14): 911-4, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26006756

RESUMO

OBJECTIVES: Chemical analysis of body fluids is commonly requested by physicians. Because most commercial FDA-cleared clinical laboratory assays are not validated by diagnostic manufacturers for "non-serum" and "non-plasma" specimens, laboratories may need to complete additional validation studies to comply with regulatory requirements regarding body fluid testing. The objective of this report is to perform recovery studies to evaluate potential body fluid matrix interferences for commonly requested chemistry analytes. DESIGN AND METHODS: Using an IRB-approved protocol, previously collected clinical body fluid specimens (biliary/hepatic, cerebrospinal, dialysate, drain, pancreatic, pericardial, peritoneal, pleural, synovial, and vitreous) were de-identified and frozen (-20°C) until experiments were performed. Recovery studies (spiking with high concentration serum, control, and/or calibrator) were conducted using 10% spiking solution by volume; n=5 specimens per analyte/body fluid investigated. Specimens were tested on a Roche cobas 8000 system (c502, c702, e602, and ISE modules). RESULTS: In all 80 analyte/body fluid combinations investigated (including amylase, total bilirubin, urea nitrogen, carbohydrate antigen 19-9, carcinoembryonic antigen, cholesterol, chloride, creatinine, glucose, potassium, lactate dehydrogenase, lipase, rheumatoid factor, sodium, total protein, triglycerides, and uric acid), the average percent recovery was within predefined acceptable limits (less than ±10% from the calculated ideal recovery). CONCLUSIONS: The present study provides evidence against the presence of any systematic matrix interference in the analyte/body fluid combinations investigated on the Roche cobas 8000 system. Such findings support the utility of ongoing body fluid validation initiatives conducted to maintain compliance with regulatory requirements.


Assuntos
Líquidos Corporais/metabolismo , Química Clínica/métodos , Humanos , Pleura/metabolismo
20.
Clin Chim Acta ; 446: 119-27, 2015 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-25888981

RESUMO

BACKGROUND: Laboratories that choose a point-of-care approach for liver function testing in patients undergoing evaluation for Ebola virus disease (EVD) have few options to choose from. The primary objective of this study was to conduct a performance characterization of a Clinical Laboratory Improvement Amendments (CLIA)-waived liver function panel on the Abaxis Piccolo® Xpress chemistry analyzer. The secondary objectives were to evaluate multiple specimen types, characterize whole blood specimen stability, and validate disposable exact transfer pipettes. Our final objective was to assess instrument airflow from a biosafety perspective. METHODS: An instrument performance characterization, including precision, linearity, accuracy, reference interval verification, and specimen type evaluation was conducted using Liver Panel Plus reagent discs on the Piccolo® Xpress. RESULTS: All assays demonstrated acceptable linearity (slopes, 0.938-1.061; observed error, 0.8-6.3%). Assay precision was 0.0-3.6% (%CV; within-day studies) and 0.9-5.6% (between-day studies). Method comparison experiments (versus Roche cobas c502/c702 chemistry analyzers) showed excellent correlation for most assays, although a few notable differences were observed (Piccolo versus Roche): alkaline phosphatase, -18.6%; amylase, -29.0%; total bilirubin, +0.3mg/dl. Pre-programmed reference intervals were verified except for the alkaline phosphatase (male and female) and alanine aminotransferase (female), which had greater than 10% of results fall below the programmed ranges. Piccolo instrument results were largely consistent across specimen types tested (lithium-heparin whole blood, lithium-heparin plasma, and serum), although some statistical differences were observed for aspartate aminotransferase, gamma glutamyltransferase, and total protein. Whole blood time course studies demonstrated that some analytes (albumin, amylase, and total protein) showed remarkable stability, while others (such as aspartate aminotransferase) showed a slight trend toward decreased activity over time. Exact volume transfer pipettes provided an effective disposable option for disc loading. Finally, airflow studies suggested that, in the context of EVD protocols, instrument placement in a biosafety level (BSL) 2 cabinet or greater is justified. CONCLUSIONS: Given its analytical performance and ease of operation, the Piccolo Xpress was transferred to a BSL-2 cabinet in our BSL-3 suite for use in our hospital's diagnostic protocol for providing liver function testing in patients undergoing evaluation for EVD.


Assuntos
Ebolavirus/isolamento & purificação , Segurança de Equipamentos/métodos , Doença pelo Vírus Ebola/diagnóstico , Laboratórios , Fígado/metabolismo , Saúde do Trabalhador , Alanina Transaminase/sangue , Fosfatase Alcalina/sangue , Amilases/sangue , Aspartato Aminotransferases/sangue , Automação Laboratorial , Bilirrubina/sangue , Feminino , Doença pelo Vírus Ebola/sangue , Doença pelo Vírus Ebola/virologia , Humanos , Fígado/virologia , Testes de Função Hepática/normas , Masculino , Sistemas Automatizados de Assistência Junto ao Leito/organização & administração , Padrões de Referência , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Utah , gama-Glutamiltransferase/sangue
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