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1.
Sensors (Basel) ; 19(20)2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31600932

RESUMO

Immunoassays have been widely used in scientific research and clinical diagnosis due to their versatile detection capability and high specificity. Immunoagglutination assays are kinds of immunoassay, which can simply and rapidly measure the concentration of analytes. In this work, we developed a low-cost micro-volume nephelometric system for quantitative immunoagglutination assays. We used off-the-shelf components to build the system, and the total cost of key components is only about 20 US dollars. The total detection volume in our system was as low as 3 µL, which could significantly reduce the reagent cost and required sample volume. We further evaluated the system performance via the immunoagglutination assay to measure the concentration of C-reactive protein, a plasma protein with levels rising in response to inflammation. The results demonstrated that our system could measure the concentration of analytes with relatively high sensitivity and precision within four minutes, and has high potential to be applied for clinical diagnostic tests.


Assuntos
Testes de Aglutinação/economia , Custos e Análise de Custo , Imunoensaio/economia , Nefelometria e Turbidimetria/economia , Proteína C-Reativa/análise , Humanos , Imageamento Tridimensional , Espalhamento de Radiação
2.
Artigo em Inglês | MEDLINE | ID: mdl-31390846

RESUMO

Climate change has often caused failure in water treatment operations. In this study, we report a real case study at a major surface water treatment plant in Alabama, USA. Following a severe winter storm, the effluent water turbidity surged to >15.00 Nephelometric Turbidity Units (NTU), far exceeding the 0.30 NTU standard. As a result, the plant operation had to be shut down for three days, causing millions of dollars of losses and affecting tens of thousands of people. Systematic jar tests were carried out with sediment samples from 22 upstream locations. The coagulation and settleability of sediment particles were tested under simulated storm weather conditions, i.e., low temperature (7 °C) and in the presence of various types and concentrations of natural organic matter (NOM) that was extracted from the local sediments. Experimental results proved that elevated NOM (6.14 mg·L-1 as Total Organic Carbon, TOC) in raw water was the root cause for the failure of the plant while the low temperature played a minor but significant role. Pre-oxidation with permanganate and/or elevated coagulant dosage were found effective to remove TOC in raw water and to prevent similar treatment failure. Moreover, we recommend that chemical dosages should be adjusted based on the TOC level in raw water, and a reference dosage of 0.29 kg-NaMnO4/kg-TOC and 19 kg- polyaluminum chloride (PACl) /kg-TOC would be appropriate to cope with future storm water impacts. To facilitate timely adjustment of the chemical dosages, the real time key water quality parameters should be monitored, such as turbidity, TOC, Ultraviolet (UV) absorbance, pH, and color. The findings can guide other treatment operators to deal with shock changes in the raw water quality resulting from severe weather or other operating conditions.


Assuntos
Hidróxido de Alumínio/química , Floculação , Compostos de Manganês/química , Óxidos/química , Purificação da Água/métodos , Tempo (Meteorologia) , Alabama , Sedimentos Geológicos/análise , Nefelometria e Turbidimetria , Oxirredução
3.
Tuberculosis (Edinb) ; 117: 1-6, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31378262

RESUMO

The purpose of this study was to develop a simple visual methyl green (MeG) based dry loop-mediated isothermal amplification (LAMP) method for early detection of Mycobacterium tuberculosis (MTB) from clinical samples. We identified MeG as an indicator of a positive LAMP reaction, where a positive reaction gave a blue-green color while a negative reaction was colorless. The MeG MTB-LAMP system was further simplified by drying all reagents for ease of use, and was then validated for its ability to diagnose TB directly using Nepalese clinical samples. We evaluated the dry MeG MTB-LAMP with 69 new TB suspected samples from patients that did not have a confirmed history of TB treatment and found the sensitivity in culture positive samples as 92.8% (13/14) and specificity in culture negative samples as 96.3% (53/55). Our LAMP system has the potential to be a point of care test for early diagnosis of active TB in developing countries.


Assuntos
Mycobacterium tuberculosis/isolamento & purificação , Técnicas de Amplificação de Ácido Nucleico/métodos , Tuberculose/diagnóstico , Corantes , DNA Bacteriano/análise , Países em Desenvolvimento , Humanos , Verde de Metila , Mycobacterium tuberculosis/genética , Nefelometria e Turbidimetria/métodos , Testes Imediatos , Estudos Retrospectivos , Sensibilidade e Especificidade
4.
Clin Lab ; 65(7)2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31307176

RESUMO

BACKGROUND: Fecal calprotectin is widely used as a marker for inflammatory bowel diseases (IBD). IBD often affects women during their reproductive years, but there are no established reference intervals during pregnancy. The aim of the present study was to define reference values during pregnancy and in the postpartum period to allow comparisons between patient results and reference values. METHODS: Fecal samples were collected from 84 healthy females during pregnancy week 26 to 28 and a second sample was collected six months after delivery. The samples were weighed, extracted, and centrifugated to remove debris. The extracted samples were then analyzed on a chemistry analyzer using a particle enhanced turbidimetric immunoassay reagent. RESULTS: The calculated reference interval during pregnancy was < 127 µg/g (90% confidence interval, 90 - 164 µg/g) and the corresponding reference interval during the postpartum period was < 143 µg/g (60 - 226 µg/g). There were no significant statistical differences between F-calprotectin values analyzed at the two sampling times. CONCLUSIONS: The reference values are slightly higher than the cutoff values of 50 - 100 µg/g often used as General cutoff for fecal calprotectin.


Assuntos
Biomarcadores/análise , Ensaio de Imunoadsorção Enzimática/métodos , Fezes/química , Complexo Antígeno L1 Leucocitário/análise , Nefelometria e Turbidimetria/métodos , Adulto , Feminino , Humanos , Doenças Inflamatórias Intestinais/diagnóstico , Doenças Inflamatórias Intestinais/metabolismo , Gravidez , Valores de Referência , Adulto Jovem
5.
Microbiol Immunol ; 63(10): 407-412, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31342547

RESUMO

Loop-mediated isothermal amplification (LAMP) assays are used to detect diverse pathogens. Initially, LAMP amplicons were detected using electrophoresis; later, real-time monitoring based on turbidity was developed to overcome the problem of contamination with environmental DNA. Recently, real-time monitoring of fluorescence signals using a quenching primer and probe has improved the reliability of amplification signals. Here, methods of detecting LAMP amplicons are reviewed.


Assuntos
Infecções Bacterianas/microbiologia , DNA Bacteriano/análise , DNA de Protozoário/análise , DNA Viral/análise , Técnicas de Amplificação de Ácido Nucleico/métodos , Infecções por Protozoários/parasitologia , Viroses/virologia , Fluorescência , Nefelometria e Turbidimetria/métodos , Reprodutibilidade dos Testes
6.
Anatol J Cardiol ; 22(1): 13-20, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31264652

RESUMO

OBJECTIVE: Left ventricle (LV) geometry and dyssynchrony are associated with LV remodeling after acute myocardial infarction (AMI). The aim of this prospective study was to assess the diagnostic value of new three-dimensional echocardiography (3DE) parameters [sphericity (SI) and systolic dyssynchrony indexes (SDI)] for the prediction of LV remodeling after AMI and to compare them with two-dimensional echocardiography (2DE) parameters. METHODS: 2DE and 3DE were performed in 75 patients with AMI within 3 days from the onset of MI and 6 months later. LV remodeling was defined as a ≥15% increase in the LV end-diastolic volume (EDV) at follow-up. 3D SI was calculated by dividing EDV by the volume of a sphere whose diameter was derived from the major end-diastolic LV long axis. SDI was considered as a standard deviation of the time from cardiac cycle onset to minimum systolic volume in 16 LV segments. RESULTS: LV remodeling was identified in 34 (45%) patients using the 2DE method and in 22 (29%) patients using the 3DE method. Evaluated 3DE parameters, such as EDV [area under the receiver operating characteristic (ROC) curve (AUC) 0.742, sensitivity 71%, specificity 79%], end-systolic volume (AUC 0.729, sensitivity 69%, specificity 78%), SDI (AUC 0.777, sensitivity 73%, specificity 77%), and SI, had significant prognostic value for LV remodeling. According to the AUC, the highest predictive value had 3D SI (AUC 0.957, sensitivity 90%, specificity 91%). CONCLUSION: 3DE parameters, especially 3D SI and SDI, play important roles in the prediction of LV remodeling after AMI and can be used in clinical practice.


Assuntos
Ecocardiografia Tridimensional/normas , Infarto do Miocárdio/diagnóstico por imagem , Disfunção Ventricular Esquerda/prevenção & controle , Remodelação Ventricular , Idoso , Área Sob a Curva , Proteína C-Reativa/análise , Estudos de Coortes , Feminino , Humanos , Técnicas Imunoenzimáticas , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/complicações , Revascularização Miocárdica , Nefelometria e Turbidimetria , Variações Dependentes do Observador , Intervenção Coronária Percutânea , Estudos Prospectivos , Curva ROC , Sensibilidade e Especificidade , Fumar , Terapia Trombolítica , Troponina I/análise , Função Ventricular Esquerda/fisiologia
7.
J Dairy Sci ; 102(8): 6820-6829, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31178183

RESUMO

We investigated the effect of different phosphate salts on the structural integrity of micellar casein (MC) at pH 7.0. With the increase of salt concentration, a reduction in turbidity was observed for the MC solutions, and it was modeled using an exponential decay function. The inflection point of the model was defined as the first critical salt concentration (C*), and it is suggested that the salt concentration initiates the disintegration of MC. For linear polyphosphates, C* decreased with the number of phosphate groups. Apparent viscosity (ηapp) of MC solutions increased with the increase of salt concentration, and they recorded a peak while the turbidity decreased to a minimum. The salt concentration that resulted in the highest ηapp was identified as the second critical salt concentration (C**). It is hypothesized that the interactions among protein species present in the mixtures are at an optimum state at C**. Both C* and C** were found to be dependent on the MC concentration. The work presented herein supports an understanding of the concentration effect of phosphate salts on MC for structuring dairy products.


Assuntos
Caseínas/química , Micelas , Fosfatos/análise , Animais , Elasticidade , Concentração de Íons de Hidrogênio , Nefelometria e Turbidimetria , Sais/química , Soluções/química , Viscosidade
8.
Food Microbiol ; 83: 109-112, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31202401

RESUMO

Using turbidity measurements to quantify bacterial growth is a common and well-established practice in microbiology. Automated devices offering high throughput analyses have largely contributed to the increase of its use. A main difficulty of this method is that it detects growth only at late exponential phase, making turbidity measurements limited for studies focussing on low cell numbers. This work proposes an improved estimator for the probability of growth of individual cells using turbidity-based measurements, when the initial number of cells is low and random. We modify the currently used estimator for the expected cell number per well, a Poisson-parameter, and show that an optimal scenario is when ca 20% of the wells do not become turbid, resulting in improved accuracy and precision.


Assuntos
Bactérias/crescimento & desenvolvimento , Nefelometria e Turbidimetria/métodos , Projetos de Pesquisa , Probabilidade
9.
Eur J Clin Microbiol Infect Dis ; 38(9): 1737-1742, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31209648

RESUMO

The conventional diagnostic techniques for catheter colonization (CC) take at least 48 h to yield results. Therefore, new diagnostic procedures that speed up the time necessary for results are needed. Our main objective was to assess the efficacy of the combination of sonication, turbidity monitoring, and MALDI-TOF to detect CC and catheter-related bloodstream infection (C-RBSI). For 1 year, we assessed central venous catheter (CVC) tips that arrived at the microbiology laboratory from adult patients admitted to our institution. CVC tips were cut, inoculated into 2.5 ml of BHI, and sonicated for 1 min. The suspension was then processed using Gram stain, quantitative culture (gold standard), and preincubation on the Alfred™ system. We analyzed the validity values of our new diagnostic approach for prediction of CC and C-RBSI and compared them with those of the gold standard. We collected a total of 167 catheters, 33 (19.8%) of which were colonized. We confirmed 21 episodes of C-RBSI. The distribution of microorganisms in colonized CVCs was as follows: Gram-positive, 68.4%; Gram-negative, 5.3%; and yeasts, 26.3%. The validity values for CC and C-RBSI using the new procedure were as follows: S, 39.4%/61.9%; Sp, 100%/100%; PPV, 100%/100%; and NPV, 87.0%/94.8%. The combination of sonication with a pre-incubation period based on turbidity monitoring using the Alfred™ system followed by MALDI-TOF proved to be a useful tool that was faster than conventional culture for ruling out C-RBSI. Future studies are needed to assess the clinical and economic impact of this diagnostic approach.


Assuntos
Bactérias/isolamento & purificação , Infecções Relacionadas a Cateter/diagnóstico , Cateteres Venosos Centrais/efeitos adversos , Nefelometria e Turbidimetria/instrumentação , Kit de Reagentes para Diagnóstico/normas , Sonicação , Idoso , Bacteriemia/diagnóstico , Bacteriemia/microbiologia , Infecções Relacionadas a Cateter/microbiologia , Cateterismo Venoso Central , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Nefelometria e Turbidimetria/métodos , Sensibilidade e Especificidade , Coloração e Rotulagem
10.
PLoS One ; 14(4): e0215376, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30978235

RESUMO

Vision is very important to fish as it is required for foraging food, fighting competitors, fleeing from predators, and finding potential mates. Vertebrates express opsin genes in photoreceptor cells to receive visual signals, and the variety of light levels in aquatic habits has driven fish to evolve multiple opsin genes with expression profiles that are highly plastic. In this study, red shiners (Cyprinella lutrensis) were exposed to four water turbidity treatments and their opsin genes were cloned to elucidate how opsin gene expression could be modulated by ambient light conditions. Opsin gene cloning revealed that these fish have single RH1, SWS1, SWS2 and LWS genes and two RH2 genes. Phylogenetic analysis also indicated that these two RH2 opsin genes-RH2A and RH2B -are in-paralogous. Using quantitative PCR, we found evidence that opsin expression is plastic in adults. Elevated proportional expression of LWS in the cone under ambient light and turbid treatment indicated that the red shiner's visual spectrum displays a red shift in response to increased turbidity.


Assuntos
Cyprinidae/genética , Proteínas de Peixes/genética , Opsinas/genética , Animais , Clonagem Molecular , Opsinas dos Cones/genética , Ecossistema , Feminino , Luz , Masculino , Mutação , Nefelometria e Turbidimetria , Filogenia , Transcriptoma
11.
Colloids Surf B Biointerfaces ; 179: 48-55, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-30947083

RESUMO

Collagen fibrillogenesis is of special significance for the maintenance of collagen scaffold's mechanical stability and biological performance. Comprehensive information about the mechanism of collagen fibrillogenesis in vitro, as well as the effect of fibrillogenesis on deposited layers of ordered collagen molecules for cellular behavior regulation is thus crucial. In the current study, the pH, phosphate ion as well as reconstitution time impacting on the in vitro fibrillogenesis was systematically investigated, including the zeta potential and turbidity measurement. Furthermore, the fibrillogenesis impacting on the π-a isotherms of collagen assembly at the air/water interface was then fully evaluated. By applying LB technique, collagen fibril-assembling arrays structure can be successfully transferred to form surface deposition onto the mica and glass substrate. The morphology and collagen content were subsequently assessed by atomic force microscopy (AFM) and hydrolyzing examination respectively. Effect of collagen LB deposition on the adhesion and proliferation of SD rat bone marrow mesenchymal stem cells were estimated by Rhodamine Phalloidin/DIPI staining and CCK8 proliferation assays. The results show that highly oriented and collagen-abundant thin film can further facilitate cell adhesion and proliferation, indicating an innovative direction for tissue engineering.


Assuntos
Colágeno/farmacologia , Células-Tronco Mesenquimais/citologia , Animais , Bovinos , Adesão Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Colágeno/química , Concentração de Íons de Hidrogênio , Células-Tronco Mesenquimais/efeitos dos fármacos , Nefelometria e Turbidimetria , Pressão , Ratos Sprague-Dawley , Eletricidade Estática , Propriedades de Superfície , Temperatura
12.
Environ Monit Assess ; 191(5): 259, 2019 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-30941608

RESUMO

Continuous sensor measurements are becoming an important tool in environmental monitoring. However, the reliability of field measurements is still too often unknown, evaluated only through comparisons with laboratory methods or based on sometimes unrealistic information from the measuring device manufacturers. A water turbidity measurement system with automatic reference sample measurement and measurement uncertainty estimation was constructed and operated in laboratory conditions to test an approach that utilizes validation and quality control data for automatic measurement uncertainty estimation. Using validation and quality control data for measurement uncertainty estimation is a common practice in laboratories and, if applied to field measurements, could be a way to enhance the usability of field sensor measurements. The measurement system investigated performed replicate measurements of turbidity in river water and measured synthetic turbidity reference solutions at given intervals during the testing period. Measurement uncertainties were calculated for the results using AutoMUkit software and uncertainties were attached to appropriate results. The measurement results correlated well (R2 = 0.99) with laboratory results and the calculated measurement uncertainties were 0.8-2.1 formazin nephelometric units (FNU) (k = 2) for 1.2-5 FNU range and 11-27% (k = 2) for 5-40 FNU range. The measurement uncertainty estimation settings (such as measurement range selected and a number of replicates) provided by the user have a significant effect on the calculated measurement uncertainties. More research is needed especially on finding suitable measurement uncertainty estimation intervals for different field conditions. The approach presented is also applicable for other online measurements besides turbidity within limits set by available measurement devices and stable reference solutions. Potentially interesting areas of application could be the measurement of conductivity, pH, chemical oxygen demand (COD)/total organic carbon (TOC), or metals.


Assuntos
Monitoramento Ambiental/métodos , Tecnologia de Sensoriamento Remoto/métodos , Rios/química , Incerteza , Qualidade da Água , Nefelometria e Turbidimetria , Controle de Qualidade , Reprodutibilidade dos Testes , Software
13.
Turk J Med Sci ; 49(2): 497-505, 2019 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-30997788

RESUMO

Background/aim: The serum immunoglobulin levels are used routinely in clinical practice because they provide key information on the humoral immune status. This study aimed to determine the age-related reference values of serum immunoglobulin levels in healthy children. Materials and methods: A total of 330 healthy children, aged between 0 and 18 years, were included in this study. The serum immunoglobulin levels were measured using a nephelometric method in a total of 11 groups, each group consisting of 30 individuals, and IgG subclasses in 6 groups of children aged more than 2 years. Results: The serum IgG levels were high during the newborn period, decreased until the sixth month, and again increased to a maximum level at the age of 18 years. The level of IgA was found to be extremely low in the newborn period and then increased with age. While the lowest value was in the newborn period for serum IgM level, the highest value was in the 16- to 18-year-old period. The IgG subclasses varied depending on the age groups. Conclusion: The updated reference intervals of immunoglobulin levels in children may be used for the accurate diagnosis of immune deficiencies.


Assuntos
Imunodeficiência de Variável Comum/sangue , Imunidade Humoral/imunologia , Imunoglobulina A/sangue , Imunoglobulina G/sangue , Imunoglobulina M/sangue , Adolescente , Criança , Pré-Escolar , Imunodeficiência de Variável Comum/imunologia , Voluntários Saudáveis , Humanos , Lactente , Recém-Nascido , Masculino , Nefelometria e Turbidimetria , Valores de Referência , Reprodutibilidade dos Testes
14.
Environ Pollut ; 250: 251-261, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30999202

RESUMO

Many portable monitors for quantifying mass concentrations of particulate matter air pollution rely on aerosol light scattering as the measurement method; however, the relationship between scattered light (what is measured) and aerosol mass concentration (the metric of interest) is a complex function of the refractive index, size distribution, and shape of the particles. In this study, we compared 33-h personal PM2.5 concentrations measured simultaneously using nephelometry (personal DataRAM pDR-1200) and gravimetric filter sampling for working adults (44 participants, 249 samples). Nephelometer- and filter-derived 33-h average PM2.5 concentrations were correlated (Spearman's ρ = 0.77); however, the nephelometer-derived concentration was within 20% of the filter-derived concentration for only 13% of samples. The nephelometer/filter ratio, which is used to correct light-scattering measurements to a gravimetric sample, had a median value of 0.52 and varied by over a factor of three (10th percentile = 0.35, 90th percentile = 1.1). When 33-h samples with >50% of 10-s average nephelometer readings below the nephelometer limit of detection were removed from the dataset during sensitivity analyses, the fraction of nephelometer-derived concentrations that were within 20% of the filter-derived concentration increased to 25%. We also evaluated how much the accuracy of nephelometer-derived concentrations improved after applying: (1) a median correction factor derived from a subset of 44 gravimetric samples, (2) participant-specific correction factors derived from one same from each subject, and (3) correction factors predicted using linear models based on other variables recorded during the study. Each approach independently increased the fraction of nephelometer-derived concentrations that were within 20% of the filter-derived concentration to approximately 45%. These results illustrate the challenges with using light scattering (without correction to a concurrent gravimetric sample) to estimate personal exposure to PM2.5 mass among mobile adults exposed to low daily average concentrations (median = 8 µg m-3 in this study).


Assuntos
Poluentes Atmosféricos/análise , Exposição Ambiental/análise , Monitoramento Ambiental/métodos , Nefelometria e Turbidimetria/métodos , Material Particulado/análise , Aerossóis/análise , Filtração/métodos , Humanos , Limite de Detecção , Tamanho da Partícula
15.
Artigo em Alemão | MEDLINE | ID: mdl-30999350

RESUMO

A sufficient supply of colostral antibodies within the first hours of life is crucial for the development and the health status in young calves. It is rational to examine the immunoglobulin uptake of single animals, but particularly on a herd basis, during herd controls and consultations. This enables economical calf rearing in accordance with animal welfare. Because of the costly, laboratory-dependent and in part time-consuming direct measurement of the absorbed immunoglobulins using radial immunodiffusion (RID) or ELISA, multiple studies attempted to develop indirect methods, which would be affordable and operational in the field. These aim to draw an inference for the absorbed quantity of colostral antibodies based on other correlated parameters. Multiple validations showed in part significant differences between various methods concerning specificity and sensitivity in comparison to the direct methods. In addition to RID and ELISA, this article presents the measurement of the γ-glutamyltransferase (GGT) activity, the determination of the total serum protein concentration using refractometry and the zinc sulphate turbidity test, and describes the advantages and disadvantages of their application. Refractory measurement and determination of the GGT activity represent a valuable alternative to a laboratory-dependent immunoglobulin G measurement. Nevertheless, there is no ideal rapid test method, such that several influencing factors have to be considered.


Assuntos
Animais Recém-Nascidos/imunologia , Bovinos/imunologia , Imunoglobulina G/sangue , Animais , Animais Recém-Nascidos/sangue , Proteínas Sanguíneas/análise , Bovinos/sangue , Colostro/imunologia , Ensaio de Imunoadsorção Enzimática/economia , Ensaio de Imunoadsorção Enzimática/métodos , Ensaio de Imunoadsorção Enzimática/veterinária , Feminino , Imunodifusão/economia , Imunodifusão/métodos , Imunodifusão/veterinária , Nefelometria e Turbidimetria/veterinária , Refratometria/veterinária , Sensibilidade e Especificidade , gama-Glutamiltransferase/sangue
16.
J Vis Exp ; (145)2019 03 12.
Artigo em Inglês | MEDLINE | ID: mdl-30933053

RESUMO

Numerous problems in scientific and engineering fields involve understanding the kinematics of particles in turbulent flows, such as contaminants, marine micro-organisms, and/or sediments in the ocean, or fluidized bed reactors and combustion processes in engineered systems. In order to study the effect of turbulence on the kinematics of particles in such flows, simultaneous measurements of both the flow and particle kinematics are required. Non-intrusive, optical flow measurement techniques for measuring turbulence, or for tracking particles, exist but measuring both simultaneously can be challenging due to interference between the techniques. The method presented herein provides a low cost and relatively simple method to make simultaneous measurements of the flow and particle kinematics. A cross section of the flow is measured using a particle image velocimetry (PIV) technique, which provides two components of velocity in the measurement plane. This technique utilizes a pulsed-laser for illumination of the seeded flow field that is imaged by a digital camera. The particle kinematics are simultaneously imaged using a light emitting diode (LED) line light that illuminates a planar cross section of the flow that overlaps with the PIV field-of-view (FOV). The line light is of low enough power that it does not affect the PIV measurements, but powerful enough to illuminate the larger particles of interest imaged using the high-speed camera. High-speed images that contain the laser pulses from the PIV technique are easily filtered by examining the summed intensity level of each high-speed image. By making the frame rate of the high-speed camera incommensurate with that of the PIV camera frame rate, the number of contaminated frames in the high-speed time series can be minimized. The technique is suitable for mean flows that are predominantly two-dimensional, contain particles that are at least 5 times the mean diameter of the PIV seeding tracers, and are low in concentration.


Assuntos
Reologia/métodos , Fenômenos Biomecânicos , Lasers , Nefelometria e Turbidimetria
17.
Front Immunol ; 10: 7, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30740097

RESUMO

Objectives: C1q is a valuable biomarker of disease activity in systemic lupus erythematosus (SLE). The "gold standard" assay, rocket immunoelectrophoresis (RIE), is time-consuming, and thus a shift to soluble immune precipitation techniques such as nephelometry has occurred. However, quantification of C1q with these techniques has been questioned as a result of the antibody binding properties of C1q. In the present work, we have compared results using various techniques (RIE, nephelometry, and ELISA) and have developed and validated a new magnetic bead-based sandwich immunoassay (MBSI). Methods: C1q was quantified by nephelometry and the new sandwich immunoassay in 45 serum samples analyzed using RIE. C1q was also assessed in plasma using RIE and sandwich immunoassay in samples from SLE patients with nephritis (n = 69), SLE patients without nephritis (n = 310) as classified by BILAG score, and matched controls (n = 322). In addition, cerebrospinal fluid (CSF) samples from 31 patients, previously analyzed with ELISA, were also analyzed with the MBSI to test the behavior of this new assay in the lower detection range. Results: We found a strong correlation between the new MBSI, RIE, and ELISA, but not with nephelometry. The MBSI demonstrated lower levels of C1q in SLE patients than in matched controls (p < 0.0001), and patients with nephritis had lower levels than patients without nephritis (p < 0.01). Similarily, RIE showed significant differences between the patient groups (p < 0.0001). An association was also found between the levels of C1q and the SLE disease activity index (SLEDAI). Furthermore, there was good correlation between the values obtained by MBSI and ELISA, in both serum (r = 0.960) and CSF (r = 0.786), underscoring the ability of both techniques to measure low concentrations of C1q with high accuracy. Conclusion: The sandwich immunoassay correlated well with RIE, but soluble immune precipitation techniques, such as nephelometry, did not appear suitable alternatives, since C1q itself, and possibly anti-C1q antibodies, interfered with the measurements. The new sandwich immunoassay is therefore a good replacement for RIE in monitoring SLE disease activity.


Assuntos
Complemento C1q/análise , Complemento C1q/líquido cefalorraquidiano , Separação Imunomagnética/métodos , Lúpus Eritematoso Sistêmico/sangue , Lúpus Eritematoso Sistêmico/líquido cefalorraquidiano , Anticorpos Monoclonais , Autoanticorpos/sangue , Biomarcadores/análise , Biomarcadores/líquido cefalorraquidiano , Complemento C1q/imunologia , Confiabilidade dos Dados , Ácido Edético , Ensaio de Imunoadsorção Enzimática/métodos , Humanos , Imunoeletroforese/métodos , Nefrite Lúpica/sangue , Nefrite Lúpica/líquido cefalorraquidiano , Campos Magnéticos , Nefelometria e Turbidimetria/métodos , Índice de Gravidade de Doença
18.
J Vis Exp ; (143)2019 01 30.
Artigo em Inglês | MEDLINE | ID: mdl-30774143

RESUMO

When present in pharmaceutical products, a Gram-negative bacterial cell wall component endotoxin (often also called lipopolysaccharide) can cause inflammation, fever, hypo- or hypertension, and, in extreme cases, can lead to tissue and organ damage that may become fatal. The amounts of endotoxin in pharmaceutical products, therefore, are strictly regulated. Among the methods available for endotoxin detection and quantification, the Limulus Amoebocyte Lysate (LAL) assay is commonly used worldwide. While any pharmaceutical product can interfere with the LAL assay, nano-formulations represent a particular challenge due to their complexity. The purpose of this paper is to provide a practical guide to researchers inexperienced in estimating endotoxins in engineered nanomaterials and nanoparticle-formulated drugs. Herein, practical recommendations for performing three LAL formats including turbidity, chromogenic and gel-clot assays are discussed. These assays can be used to determine endotoxin contamination in nanotechnology-based drug products, vaccines, and adjuvants.


Assuntos
Bioensaio/métodos , Endotoxinas/análise , Caranguejos Ferradura/metabolismo , Nanopartículas/química , Animais , Doxorrubicina/análogos & derivados , Doxorrubicina/farmacologia , Nefelometria e Turbidimetria , Polietilenoglicóis/farmacologia
19.
Scand J Clin Lab Invest ; 79(1-2): 50-57, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30761918

RESUMO

Calprotectin in plasma and blood might prove to be a useful biomarker of inflammation and infection; however, automated methods for analysing the concentration of calprotectin in those materials are lacking. We have validated a fully automated turbidimetric method and present health-related reference limits. Calprotectin was measured by Siemens Advia XPT with the Bühlmann fCAL® turbo test (Bühlmann Laboratories AG, Schönenbuch, Switzerland), a particle enhanced turbidimetric immunoassay for quantification of calprotectin in fecal extracts. Plasma and serum samples were analysed directly, while whole blood was first extracted with M-PER® Mammalian Protein Extraction Reagent (ThermoFisher) and diluted with B-CAL-EX (Bühlmann). We studied analytical imprecision, estimated health-related reference limits and examined the correlation between neutrophil-calprotectin (blood-calprotectin adjusted for plasma-calprotectin) and the neutrophil count. The intermediate ('day-to-day') coefficient of variation was 3.5 and 1.0% for heparin-plasma-calprotectin at 0.52 mg/L and 3.53 mg/L, respectively, and 4.9% for heparin-blood-calprotectin at 50.2 mg/L. Health-related reference limits were 0.470-3.02 mg/L for calprotectin in heparin-plasma, 50.8-182 mg/L for calprotectin in heparin-blood, 0.534-2.41% for the ratio between them and 24.7-33.3 pg for the mean amount of calprotectin per neutrophil. Compared to heparin-plasma, calprotectin concentrations were significantly lower in EDTA-plasma and higher in serum (p < .05). Correlation between neutrophil-calprotectin and the neutrophil count was excellent. We have shown that the Bühlmann fCAL® turbo test can be used to measure calprotectin in plasma and blood.


Assuntos
Imunoensaio/normas , Complexo Antígeno L1 Leucocitário/sangue , Nefelometria e Turbidimetria/normas , Neutrófilos/citologia , Anticoagulantes/química , Ácido Edético/química , Fezes/química , Heparina/química , Humanos , Contagem de Leucócitos , Limite de Detecção , Neutrófilos/metabolismo , Variações Dependentes do Observador , Valores de Referência , Reprodutibilidade dos Testes
20.
Phys Med Biol ; 64(4): 045016, 2019 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-30630136

RESUMO

Angle-resolved light scattering measurements of human metaphase chromosomes were compared to the results of numerical light scattering simulations with geometrical models based on atomic force microscopy (AFM) measurements of the same chromosomes. The simulations were conducted using the discrete dipole approximation method (DDA), which solves Maxwell's equations for induced dipoles, positioned in a discrete lattice. A remarkable agreement between the light scattering simulations and measurements of all 6 studied chromosomes was found. Additionally, the influence of small changes in the orientation of a complex scatterer geometry on its angle-resolved scattering pattern is shown. A method is presented to approximate such variations in the scatterer's orientation by a linear shift of the angular scattering pattern. This method provides an initial guess on the scatterers orientation, reducing the amount of simulations needed considerably. It was validated on simulations of a cuboid and successfully applied in the evaluation of the chromosome measurements.


Assuntos
Cromossomos Humanos , Simulação por Computador , Luz , Espalhamento de Radiação , Humanos , Nefelometria e Turbidimetria
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