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1.
PLoS One ; 15(6): e0234361, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32525946

RESUMO

Artificial gravity elicited through short-arm human centrifugation combined with physical exercise, such as jumping, is promising in maintaining health and performance during space travel. However, motion sickness symptoms could limit the tolerability of the approach. Therefore, we determined the feasibility and tolerability, particularly occurrence of motion sickness symptoms, during reactive jumping exercises on a short-arm centrifuge. In 15 healthy men, we assessed motion sickness induced by jumping exercises during short-arm centrifugation at constant +1Gz or randomized variable +0.5, +0.75, +1, +1.25 and +1.5 Gz along the body axis referenced to center of mass. Jumping in the upright position served as control intervention. Test sessions were conducted on separate days in a randomized and cross-over fashion. All participants tolerated jumping exercises against terrestrial gravity and on the short-arm centrifuge during 1 Gz or variable Gz at the center of mass without disabling motion sickness symptoms. While head movements markedly differed, motion sickness scores were only modestly increased with jumping on the short-arm centrifuge compared with vertical jumps. Our study demonstrates that repetitive jumping exercises are feasible and tolerable during short-arm centrifugation. Since jumping exercises maintain muscle and bone mass, our study enables further development of exercise countermeasures in artificial gravity.


Assuntos
Centrifugação/efeitos adversos , Gravidade Alterada/efeitos adversos , Enjoo devido ao Movimento/etiologia , Voo Espacial , Adaptação Fisiológica , Adulto , Medicina Aeroespacial , Centrifugação/instrumentação , Exercício Físico/fisiologia , Gravitação , Movimentos da Cabeça/fisiologia , Voluntários Saudáveis , Humanos , Masculino , Enjoo devido ao Movimento/fisiopatologia , Enjoo devido ao Movimento/prevenção & controle , Contramedidas de Ausência de Peso , Adulto Jovem
3.
Curr Med Sci ; 40(1): 110-116, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32166672

RESUMO

We investigated whether an ordinary centrifuge can achieve the standard centrifugal effect required according to specifications for infectious disease screening using the Abbott i2000. Samples were collected and centrifuged following a standard operating procedure (SOP). They were then divided into three groups according to the results of the initial screening tests: a negative group, weak-positive group, and positive group. Twenty negative samples and all weak-positive and positive samples were re-analyzed. Two tubes for each re-analyzed sample were centrifuged simultaneously, one for 10 min at 10 000 × g, per recommendations, and one for 10 min at 2750 × g. No significant difference was found between the groups using different centrifugal forces. There was a strong correlation in the quantitative values between the two conditions of centrifugation. Consistency analysis showed a Cronbach's alpha > 0.8 for detection of Treponema pallidum, human immunodeficiency virus (HIV), hepatitis C virus (HCV), and hepatitis B surface antigen in the three groups (negative group, weak-positive group, and positive group) under different centrifugation conditions. Strong consistency was found under different centrifugal conditions, regardless of the initial testing results. In conclusion, we conducted centrifugation steps in duplicate, according to infectious disease screening protocols. Our study showed that all samples should be centrifuged using a recommended relative centrifugal force after a proper clotting time, as in the standard operating procedure of our laboratory. In this way, we were able to obtain the same results using an ordinary centrifuge as those obtained using a high-speed centrifuge, such as the Abbott i2000.


Assuntos
Centrifugação/métodos , Doenças Transmissíveis/diagnóstico , Manejo de Espécimes/instrumentação , Centrifugação/instrumentação , Centrifugação/normas , Guias como Assunto , HIV/isolamento & purificação , Hepacivirus/isolamento & purificação , Antígenos de Superfície da Hepatite B/metabolismo , Vírus da Hepatite B/isolamento & purificação , Humanos , Sensibilidade e Especificidade , Treponema pallidum/isolamento & purificação
4.
Clin Oral Investig ; 24(3): 1171-1182, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31321574

RESUMO

OBJECTIVES: Platelet-rich fibrin (PRF) has gained tremendous momentum in recent years as a natural autologous growth factor derived from blood capable of stimulating tissue regeneration. Owing to its widespread use, many companies have commercialized various centrifugation devices with various proposed protocols. The aim of the present study was to compare 3 different commercially available centrifuges at both high and low g-force protocols. MATERIALS AND METHODS: PRF was produced on three commercially available centrifuges including the IntraSpin Device (IntraLock), the Duo Quattro (Process for PRF), and Salvin (Salvin Dental). Two separate protocols were tested on each machine including the original leukocyte and platelet-rich fibrin (L-PRF) protocol (~ 700 RCF max (~ 400 RCF clot) for 12 min) as well as the advanced platelet-rich fibrin (A-PRF+) protocol (~ 200 g RCF max (~ 130 g RCF clot) for 8 min). Each of the tested groups was compared for cell numbers, growth factor release, scanning electron microscopy (SEM) for morphological differences, and clot size (both weight and length/width). RESULTS: The present study found that PRF clots produced utilizing the low-speed centrifugation speeds (~ 200 g for 8 min) produce clots that (1) contained a higher concentration of evenly distributed platelets, (2) secreted higher concentrations of growth factors over a 10 day period, and (3) were smaller in size. This was irrespective of the centrifugation device utilized and consistently observed on all 3 devices. The greatest impact was found between the protocols utilized (up to a 200%). Interestingly, it was further revealed that the centrifugation tubes used had a much greater impact on the final size outcome of PRF clots when compared to centrifugation devices. It was found that, in general, the Process for PRF tubes produced significantly greater-sized clots when compared to other commercially available tubes. The Salvin Dental tubes also produced significantly greater PRF clots when compared to the IntraLock tubes on each of the tested centrifugation devices. CONCLUSIONS: The present study demonstrated the reproducibility of a scientific concept (reduction in RCF produces PRF clots with more evenly distributed cells and growth factors) utilizing different devices. Furthermore, (and until now overlooked), it was revealed for the first time that the centrifugation tubes are central to the quality production of PRF. Future research investigating tube characteristics thus becomes critically important for the future optimization of PRF. CLINICAL RELEVANCE: This is the first study to reveal the marked impact of centrifugation tubes on the final production of PRF. Future study thus becomes markedly important to further optimize the quality of PRF-based matrices. It was further found that little variability existed between the centrifugation devices if optimized centrifugation protocols (lower centrifugation speeds) were utilized.


Assuntos
Centrifugação/instrumentação , Fibrina Rica em Plaquetas , Humanos , Reprodutibilidade dos Testes
5.
J Steroid Biochem Mol Biol ; 198: 105572, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31883923

RESUMO

The tendency of steroid molecules to adsorb to various materials, particularly plastics, has been known of for decades but has not received widespread attention in the scientific community, and a modern, systematic study is lacking. This adsorption is an important consideration for researchers working with steroid hormones as it could skew the results of various experiments. Here we show that steroids adsorb to various vessels used in experiments, including microcentrifuge tubes, glass vials, and cell culture plates, in a manner that depends on the steroid's molecular structure and on the type of vessel. The lipophilicity of steroids is a strong predictor of the degree of adsorption, with nearly 50 % of the most lipophilic steroid tested, pregnenolone, retained in a high-adsorbing microcentrifuge tube after one hour incubation of an aqueous pregnenolone solution followed by removal of the aqueous solvent. We also show the effects of other factors such as incubation time, centrifugation, and temperature on adsorption, and show that adsorption can be mostly prevented by the presence of serum proteins in steroid solutions and/or by the use of low-adsorbing tubes.


Assuntos
Hormônios/isolamento & purificação , Esteroides/isolamento & purificação , Adsorção , Linhagem Celular Tumoral , Centrifugação/instrumentação , Técnicas de Laboratório Clínico/instrumentação , Hormônios/química , Humanos , Masculino , Pregnenolona/química , Pregnenolona/isolamento & purificação , Soluções , Esteroides/química , Temperatura
6.
Anal Sci ; 35(10): 1123-1127, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31597872

RESUMO

Measurement of single molecule interaction is performed by various micromanipulation techniques. However, a complex operation is required to perform the measurement, so the measurement throughput is low and a large amount of time is required for statistical analysis. In this paper, we propose a method for measuring intermolecular interactions that applies a tensile force to the intermolecular bond by using centrifugal force and can easily measure binding force. The binding force of an antigen-antibody reaction system was measured by the use of the proposed method as a proof of concept. The measured binding forces were distributed in the range of 19 - 133 pN. The values obtained by use of the proposed method were consistent with the conventional method. This result is promising for applications that require further development, such as the development of a biosensor as a novel measuring technique that is based on the intermolecular interaction measurement.


Assuntos
Centrifugação/instrumentação , Dispositivos Lab-On-A-Chip , Resistência à Tração , Anticorpos Imobilizados/química , Anticorpos Imobilizados/imunologia , Microscopia de Força Atômica , Microesferas , Poliestirenos/química
7.
Artif Organs ; 43(9): 849-859, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31321785

RESUMO

Mechanical circulatory support devices have been used clinically for patients with heart failure for over 10 years. However, thrombus formation inside blood pumps remains a risk to patient life, causing pump failure and contributing to neurological damage through embolization. In this article, we propose a method for preventing thrombus formation by applying vibrational excitation to the impeller. We evaluate the ability of this method to enhance the antithrombogenic properties of a magnetically levitated centrifugal blood pump and ensure that the impeller vibration does not cause undue hemolysis. First, 3 vibrational conditions were compared using an isolated pump without a mock circulation loop; the vibrational excitation frequencies and amplitudes for the impeller were set to (a) 0 Hz-0 µm, (b) 70 Hz-10 µm, and (c) 300 Hz-2.5 µm. The motor torque was measured to detect thrombus formation and obtain blood coagulation time by calculating the derivative of the torque. Upon thrombus detection, the pump was stopped and thrombi size were evaluated. The results showed an increase in the blood coagulation time and a decrease in the rate of thrombus formation in pumps with the impeller vibration. Second, an in vitro hemolysis test was performed for each vibrational condition to determine the effect of impeller vibration on hemolysis. The results revealed that there was no significant difference in hemolysis levels between each condition. Finally, the selected vibration based on the above test results and the non-vibration as control were compared to investigate antithrombogenic properties under the continuous flow condition. The blood coagulation time and thrombi size were investigated. As a result, vibrational excitation of the impeller at a frequency of 300 Hz and amplitude of 2.5 µm was found to significantly lengthen clotting time, decreasing the rate of pump thrombus compared to the non-vibration condition. We indicate the potential of impeller vibration as a novel mechanical antithrombogenic mechanism for rotary blood pumps.


Assuntos
Circulação Assistida/instrumentação , Coração Auxiliar/efeitos adversos , Trombose/etiologia , Animais , Circulação Assistida/efeitos adversos , Coagulação Sanguínea , Centrifugação/efeitos adversos , Centrifugação/instrumentação , Desenho de Equipamento , Hemólise , Humanos , Magnetismo/instrumentação , Suínos , Trombose/sangue , Trombose/prevenção & controle , Vibração
8.
Biosens Bioelectron ; 141: 111466, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31254863

RESUMO

Since the emergence of the lab-on-a-chip technology in 1979, a variety of microfluidic devices have been developed and utilized for chemical and biological applications. Among the microfluidic devices, the centrifugal microfluidic device or lab-on-a-disc (LOAD) has advanced remarkably due to simple operation by the rotation, total integration, and high-throughput capability. Moreover, the centrifugal microdevices do not need complex tubing and pumping systems, which render them ideal for point-of-care testing (POCT) system. Owing to these characteristics, the centrifugal microdevices have been extensively used for bio-diagnostics. In particular, molecular diagnostics, which are regarded as an essential method for definite determination of the targets related with diseases, have been widely applied on the LOAD. In this review paper, we focus on the molecular diagnostics on the LOAD. The steps for the molecular diagnostics such as cell lysis, genome purification, gene amplification, amplicon detection, and data analysis can be performed individually or totally on the LOAD. Future directions of the LOAD in the fields of bio-diagnostics is to realize POCT for U-healthcare monitoring. In this context, the latest LOAD strategies for molecular diagnostics are summarized in this review paper, which would provide an insight for future POCT platform.


Assuntos
Dispositivos Lab-On-A-Chip , Ácidos Nucleicos/análise , Testes Imediatos , Reação em Cadeia da Polimerase/instrumentação , Animais , Centrifugação/instrumentação , Desenho de Equipamento , Humanos , Ácidos Nucleicos/genética
9.
Prep Biochem Biotechnol ; 49(8): 813-821, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31169457

RESUMO

Separation of biomass from culture media by centrifugation and then washing the biomass are mandatory steps in the fermentation process of recombinant Pichia pastoris expressed HBsAg intracellularly. Biomass has to be washed many times to eliminate the culture media residues thoroughly. In this study, we tried to develop the hydrocyclone as an alternative method for separation of biomass from fermentation culture, an attractive replacement for centrifugation processes. The advantages of using hydrocyclone in biomass separation could be summarized in its suitability for continuous separation and its low risk of contamination. To evaluate the performance of hydrocyclone, concentration ratio in underflow to feed stream, capacity, and centrifugal force by considering three parameters of pressure drop, concentration, and the type of hydrocyclone were investigated. Using three level factorial design a concentration ratio equation was developed, with the correlation coefficient R2 = 0.977 ensured the good fitness of the predicted data with the experimental results. In optimal conditions, maximum concentration ratio was 1.246, for flow rate 13.5 LPM and C-force equal to 1276.11 at maximum pressure drop (3 bar) and minimum concentration (0.5% w/w) in hydrocyclone 1. Herein, two different hydrocyclones with the cylindrical diameters of 19 mm and 21 mm were used for separating the yeast cells.


Assuntos
Centrifugação/instrumentação , Meios de Cultura/química , Antígenos de Superfície da Hepatite B/isolamento & purificação , Pichia/química , Técnicas de Cultura Celular por Lotes/instrumentação , Biomassa , Desenho de Equipamento , Fermentação , Pressão , Proteínas Recombinantes/isolamento & purificação
10.
Matern Child Nutr ; 15 Suppl 3: e12791, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31148399

RESUMO

Good nutrition during a child's early years lays a strong foundation of health for the rest of its life. Yet in India, there is widespread prevalence of undernourishment among children below 5 years of age. Within the Indian context, small millets have great potential as a healthy food to address this challenge by the virtue of their nutritional qualities. However, there are many problems with the current processing technology for small millets, whereas the use of value-added products was minimal. To address this, an assessment of existing small millet processing machinery was undertaken, and a double chamber centrifugal dehuller was developed, which had higher recovery of dehulled unpolished millets and met requirements at the village and enterprise levels. To demonstrate the health benefits of consuming value-added small millets, a study of supplementation of multi-millet health mix on the nutritional status of primary schoolchildren was conducted in Thondamuthur Block of Coimbatore District, India. Multi-millet health mix was formulated from kodo millet, little millet, foxtail millet, finger millet, and wheat with the inclusion of pulses. It contained 65.45-g carbohydrate, 11.46-g protein, 4.94-g fat, 4.94-g fibre, 4.07-mg iron, 112-mg calcium, 268.52-mg phosphorus, and 349 calories of energy per 100 g. The study indicated that there was a significant increase in height, weight, and haemoglobin level of the schoolchildren who regularly consumed the formulated multi-millet health mix. The improved huller and value-added food product developed can be feasible options for improving nutrition security and livelihoods through increased use of small millets.


Assuntos
Centrifugação/instrumentação , Suplementos Nutricionais , Desnutrição/prevenção & controle , Milhetes , Valor Nutritivo , Panicum , Criança , Pré-Escolar , Grão Comestível , Tecnologia de Alimentos/instrumentação , Humanos , Índia/epidemiologia , Estado Nutricional
11.
PLoS Biol ; 17(5): e3000251, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31112539

RESUMO

The centrifuge is an essential tool for many aspects of research and medical diagnostics. However, conventional centrifuges are often inaccessible outside of standard laboratory settings, such as remote field sites, because they require a constant external power source and can be prohibitively costly in resource-limited settings and Science, technology, engineering, and mathematics (STEM)-focused programs. Here we present the 3D-Fuge, a 3D-printed hand-powered centrifuge, as a novel alternative to standard benchtop centrifuges. Based on the design principles of a paper-based centrifuge, this 3D-printed instrument increases the volume capacity to 2 mL and can reach hand-powered centrifugation speeds up to 6,000 rpm. The 3D-Fuge devices presented here are capable of centrifugation of a wide variety of different solutions such as spinning down samples for biomarker applications and performing nucleotide extractions as part of a portable molecular lab setup. We introduce the design and proof-of-principle trials that demonstrate the utility of low-cost 3D-printed centrifuges for use in remote field biology and educational settings.


Assuntos
Centrifugação/instrumentação , Biologia Molecular , Impressão Tridimensional/instrumentação , Genômica , Nanoporos , Nucleotídeos/isolamento & purificação , Proteínas/análise , Floresta Úmida , Manejo de Espécimes , Biologia Sintética
12.
Lab Chip ; 19(9): 1657-1664, 2019 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-30931470

RESUMO

Nucleic acid amplification methods are increasingly being used to detect trace quantities of DNA in samples for various diagnostic applications. However, quantifying the amount of DNA from such methods often requires time consuming purification, washing or labeling steps. Here, we report a novel microfluidic centrifugation assisted precipitation (µCAP) method for single-step DNA quantification. The method is based on formation of a visible precipitate, which can be quantified, when an intercalating dye (GelRed) is added to the DNA sample and centrifuged for a few seconds. We describe the mechanism leading to the precipitation phenomenon. We utilize centrifugal microfluidics to precisely control the formation of the visible and quantifiable mass. Using a standard CMOS sensor for imaging, we report a detection limit of 45 ng µl-1. Furthermore, using an integrated lab-on-DVD platform we recently developed, the detection limit is lowered to 10 ng µl-1, which is comparable to those of current commercially available instruments for DNA quantification. As a proof of principle, we demonstrate the quantification of LAMP products for a HIV-1B type genome containing plasmid on the lab-on-DVD platform. The simple DNA quantification system could facilitate advanced point of care molecular diagnostics.


Assuntos
Centrifugação/instrumentação , Precipitação Química , DNA/análise , DNA/isolamento & purificação , Dispositivos Lab-On-A-Chip , DNA/genética , Genoma Viral/genética , HIV-1/genética , Técnicas de Amplificação de Ácido Nucleico
13.
Lab Chip ; 19(11): 1941-1952, 2019 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-30997461

RESUMO

This paper describes the development of an on-chip nucleic acid (NA) extraction assay from whole blood using a centrifugal microfluidic platform that allows for pneumatic actuation of liquids during rotation. The combination of pneumatic and centrifugal forces makes it possible to perform fluidic operations without the need for integrating active control elements on the microfluidic cartridge. The cartridge is fabricated from thermoplastic polymers (e.g., Zeonor 1060R) and features a simple design that is compatible with injection molding. In addition, the cartridge is interfaced with two external vials for off-chip storage of the blood sample and retrieval of the eluted NA solution, respectively. On-chip capture of NAs is performed using an embedded solid-phase extraction matrix composed of commercial glass microfiber filters (Whatman GF/D and GF/F). The yield of the automated, on-chip extraction protocol, determined by measuring absorbance at 260 nm, is comparable to some of the best manually operated kits (e.g., Qiagen QIAamp DNA Mini Kit) while providing low assay-to-assay variability due to the high level of control provided by the platform for each processing step. The A260/A280 and A260/A230 ratios of the absorbance spectra also reveal that protein contamination of the sample is negligible. The capability of the pneumatic platform to circulate air flux through the microfluidic conduit was used to dry leftover ethanol residues retained in the capture matrix during washing. This method, applied in combination with localized heating, proved effective for reducing ethanol contamination in eluted samples from ∼12% to 1% (v/v).


Assuntos
Métodos Analíticos de Preparação de Amostras/métodos , Centrifugação/instrumentação , Dispositivos Lab-On-A-Chip , Ácidos Nucleicos/sangue , Ácidos Nucleicos/isolamento & purificação , Automação , DNA Bacteriano/sangue , DNA Bacteriano/isolamento & purificação , Desenho de Equipamento , Escherichia coli O157/genética
14.
Lab Chip ; 19(10): 1728-1735, 2019 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-31020298

RESUMO

The lab-on-a-disc is a powerful microfluidic platform that skillfully takes advantage of centrifugal force to controllably drive liquids with the assistance of passive or active valves. However, the passive valves are mainly triggered by the rotation speed and can be easily influenced by the surface chemistry of the channel, while the active valves usually require a complicated fabrication or actuation procedure. In this study, a novel active valve that can be easily triggered by an electromagnet was proposed and applied on the centrifugation platform. This valve, named the electromagnet-triggered pillar (ETP) valve, consisted of a metal pin and pressure sensitive adhesive (PSA) tape, and is closed until the pin is lifted up by an electromagnet to partially separate the PSA tape from the substrate. As a typical application, this valve is utilized to construct a centrifugal chip for mycotoxin detection. With four ETP valves in a unit, the sample and liquid reagents can be sequentially released into the reaction chamber that was spotted with mycotoxin conjugates to accomplish the whole immunoassay. Four mycotoxins (aflatoxin B1, ochratoxin A, T-2 toxin, and zearalenone) were simultaneously detected on this chip with limits of detection lower than the permissible limits set by the regulatory agencies of China, demonstrating the practicability of this easy-to-use active valve.


Assuntos
Centrifugação/instrumentação , Imunoensaio/instrumentação , Imunoensaio/métodos , Imãs , Técnicas Analíticas Microfluídicas , Micotoxinas/análise , Animais , Bovinos , Camundongos , Soroalbumina Bovina/química
15.
Int J Artif Organs ; 42(6): 291-298, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30854913

RESUMO

Flow rate estimation for ventricular assist devices without additional flow sensors can improve the quality of life of patients. In this article, a novel flow estimation method using the passively stabilized displacement of a magnetically levitated impeller is developed to achieve sufficient accuracy and precision of flow estimation for ventricular assist devices in a simple manner. The magnetically levitated impeller used is axially suspended by a magnetic bearing in a centrifugal blood pump that has been developed by our group. The radial displacement of the impeller, which is restricted by passive stability, can be correlated with the flow rate because the radial hydraulic force on the impeller varies according to the flow rate. To obtain the correlation with various blood viscosities, the relationships between the radial displacements of the magnetically levitated impeller and the pressure head-flow rate characteristics of the pump were determined simultaneously using aqueous solutions of glycerol with a potential blood viscosity range. The measurement results showed that accurate steady flow rates could be estimated with a coefficient of determination of approximately 0.97 and mean absolute error of approximately 0.22 L/min without fluid viscosity measurements by using the relationships between the impeller displacement and the flow rate. Moreover, a precision of approximately 0.01 (L/min)/µm was obtained owing to a strong estimation indicator signal provided by the large displacement of the passively stabilized impeller; thus, the proposed estimation method can help ensure sufficient accuracy and precision for ventricular assist devices in a simple manner, even if the blood viscosity is unknown.


Assuntos
Centrifugação , Coração Auxiliar/normas , Qualidade de Vida , Velocidade do Fluxo Sanguíneo , Centrifugação/instrumentação , Centrifugação/métodos , Desenho de Equipamento , Insuficiência Cardíaca/psicologia , Insuficiência Cardíaca/terapia , Humanos , Imãs
16.
Forensic Sci Int ; 297: 204-216, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30831412

RESUMO

Diatom analysis is very effective for positive diagnosis of water inhalation in drowning. However, conventional strong acid diatom testing is laborious and potentially dangerous. We propose a simple, fast, and safe protocol using inexpensive reagents such as papain, SDS, and 5 N HCl for extracting diatoms from lung, kidney, and liver tissues. First, we determined optimal conditions for papain digestion using porcine tissues. Papain digestion was clearly superior to Proteinase K digestion. Next, for assessing the assay effectiveness in practical cases, the papain digestion protocol was applied to 80 tissue samples from 20 suspected drowning victims. Left and right lung tissues (1 g each) were digested in 15-mL conical centrifuge tubes. Kidney and liver tissues (10 g each) were extracted in 175-mL conical centrifuge bottles. Papain dissolved all organs sufficiently and permitted clear visualization of diatoms, although papain's solubilization activity was still inferior to strong acid digestion. The proposed enzymatic method requires only a low-speed centrifuge and water bath. Diatoms typically can be extracted from tissue samples within 3-5 h. The cost of protease is reduced some 6-fold by using papain in place of Proteinase K. Thus, the proposed method can be useful as a less-laborious, less-hazardous, and less-costly minimal test when the conventional strong acid digestion method is not performed due to personnel, equipment, budgetary limitation, or environmental and safety considerations.


Assuntos
Diatomáceas/isolamento & purificação , Afogamento/diagnóstico , Patologia Legal/métodos , Indicadores e Reagentes , Papaína , Animais , Cadáver , Centrifugação/instrumentação , Endopeptidase K , Humanos , Incubadoras , Rim/patologia , Fígado/patologia , Pulmão/patologia , Manejo de Espécimes/métodos , Suínos
17.
J Chromatogr A ; 1596: 134-141, 2019 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-30862407

RESUMO

The partition efficiencies of three different coiled columns, conventional multilayer coiled column, eccentric coiled column and toroidal coiled column, were evaluated by the separation of 4-methylumbelliferyl sugar derivatives using the coil satellite centrifuge (CSC) with an organic-aqueous two-phase solvent system composed of ethyl acetate/1-butanol/water. The CSC apparatus was reinforced the planet axis to maintain the stable satellite motion, which was completed by combining the rotation of three axes including the sun axis (the angular velocity, ω1), the planet axis (ω2) and the satellite axis (ω3) under the relation at ω1 = ω2 + ω3. In the present study, four different rotation speed combination types were used for the separation at the ratio (ω1, ω2, ω3) = I. (300, 150, 150), II. (300, 100, 200), III. (300, 147, 153) and IV. (300, 200, 100 rpm) under different revolution speeds of ω1 = 300, 400 and 500 rpm. In the conventional multilayer coiled column with the upper mobile phase, the rotation speed combination type II yielded the best peak resolution while the rotation speed combination types III and IV had extremely low stationary phase retention even at higher revolution speeds. This inconvenience was eliminated by using the eccentric and the toroidal coiled column. The rotation speed combination type II for the eccentric coiled column and the type IV for the toroidal coiled column produced the best separation in both the upper and the lower mobile phases among four different rotation speed combination types. The overall results indicated that better peak resolution was obtained by the eccentric coiled column than by the toroidal coiled column except for the separation with the upper mobile phase at the low revolution speed.


Assuntos
Centrifugação/instrumentação , Técnicas de Química Analítica/métodos , 1-Butanol/química , Acetatos/química , Rotação , Solventes/química , Água/química
18.
Chemosphere ; 222: 671-678, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30735967

RESUMO

Measurement and reporting of concentrations of contaminants of emerging concern such as per- and polyfluoroalkyl substances (PFASs), including perfluorooctanoic acid (PFOA), is an integral part of most investigations. Occurrence of sorption losses of PFAS analytes onto particular laboratory-ware (e.g. glass containers) has been suggested in the published literature but has not been investigated in detail. We examined sorption losses from aqueous PFOA solutions in contact with different commonly-used materials in filter units and centrifuge tubes (glass and plastics). Sorption of PFOA onto different filter membrane types ranged from 21-79% indicating that filtration can introduce a major source of error in PFOA analysis; pre-treatment of filter membranes with phosphate or methanol solutions did not improve PFOA recovery. Substantial adsorption of PFOA was also observed on tubes made from polypropylene (PP), polystyrene (PS), polycarbonate (PC), and glass where losses observed were between 32-45%, 27-35%, 16-31% and 14-24%, respectively. Contrary to suggestions in the literature, our results indicated that the greatest sorption losses for PFOA occurred on PP, whereas losses on glass tubes were much lower. Variations in ionic strength and pH did not greatly influence PFOA recovery. When PFOA concentrations were increased, the percent recovery of PFOA increased, indicating that binding sites on tube-walls were saturable. This study draws attention towards analytical bias that can occur due to sorption losses during routine procedures, and highlights the importance of testing the suitability of chosen laboratory-ware for specific PFAS analytes of interest prior to experimental use.


Assuntos
Adsorção , Caprilatos/análise , Poluentes Ambientais/análise , Fluorcarbonetos/análise , Centrifugação/instrumentação , Filtração/instrumentação , Poluentes Químicos da Água/isolamento & purificação
19.
Talanta ; 194: 903-909, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30609623

RESUMO

A microfluidic SERS chip integrated with blood separation and in-situ detection was designed and fabricated for the rapid detection of clinical blood samples. Each functional unit in the microfluidic SERS chip consist of separation-decantation cavity based on centrifugal separation principle, mixing channels and SERS detection chamber built with integrated nano-Au on Ag film microstructure. The serum creatinine was selected as a typical sample to demonstrate the capability of microfluidic SERS chip. It was found that the creatinine SERS characteristic peaks at 678 cm-1 can be effectively identified and the detection limit could be as low as 4.42 × 10-3 µmol mL-1 in water. The blood samples were also tested in microfluidic SERS chip. The whole separation and test process could be completed within 2 min, which is a significant improvement in the field of creatinine detection. The whole blood of six cases clinical blood samples were also tested, and the results were consistent with the enzymatic results. The developed microfluidic SERS chip has advantages including reduction of the required quantity of blood sample, reusable and easy to operate. It is expected to provide a new method for rapid diagnostics.


Assuntos
Centrifugação/instrumentação , Dispositivos Lab-On-A-Chip , Testes Imediatos , Análise Espectral Raman/instrumentação , Desenho de Equipamento , Ouro/química , Humanos , Falência Renal Crônica/diagnóstico , Nanopartículas Metálicas/química , Prata/química , Fatores de Tempo
20.
Anaerobe ; 55: 61-66, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30315963

RESUMO

Clostridium difficile is a Gram-positive spore forming rod-shaped bacterium which causes mild to severe diarrhea. Spores play a key role in transmission of C. difficile in hospital environment. To investigate ability of spores to stay on fomites and to assess levels of contamination it is essential to prevent loss of spores collected for the analysis. Working with C. difficile spores we noticed a significant loss after vortexing of spore suspensions and investigated if it can be prevented by using a specific brand or type of microcentrifuge tubes. 7 types of microcentrifuge tubes from 3 manufacturers were tested. Spores of three types of C. difficile, NAP1/027, NAP4/014 and NAP7/078 (clinical isolates) were used. C. difficile was grown on Brucella Supplemented Agar for 9 days, spores were collected, washed and density of 3 suspensions was normalized to optical density (OD) 550 0.1 or 0.05. These suspensions (OD 0.1) were used in serial dilutions with 3 experimental conditions - pipetting, vortexing or vortexing in 3% albumin solution and in vortexing experiment when 150 µl were vortexed for 1 min at 1500 rpm per tube and loss of spores was measured by a decrease in dipicolinic acid (DPA) concentration measured by time-delayed terbium fluorescence. Inner surface of the tubes was visualized with microscopy to observe adhered spores. In serial dilution experiment, initial concentration of spores would be underestimated by up to 18X in case of vortexing for NAP1 strain and 9X for NAP4 strain. Presence of 3% albumin significantly decreases this effect but does not eliminate it completely. Comparison of 7 types of tubes shows that a single vortexing for 1 min of diluted spore suspension at concentrations of 1.8 × 107 spores per ml leads to a loss of up to 90% of spores in some tubes. Degree of spores' adhesion varied between brands and types of tubes and between tubes of the same type. In some brands there was a significant variability in adhesion between tubes from the same batch. Microscopy after vortexing shows a film of spores attached to the tube's wall. Adherence could be affected by the type of plastic, additives (plasticizers) used in manufacturing and quality of moulds (e.g."diamond polished"). To identify the most appropriate type of tubes for the experiment it is essential to test it beforehand as not every brand is suitable for this purpose. Using tubes with a high degree of adherence could significantly affect measurement of spores' concentration in serial dilutions, e.g. when quantifying spores production by a specific strain or when limits of detection are measured. Also, sensitivity of commercial tests for detection of C. difficile in clinical specimens can be decreased if an unsuitable type of plastic containers and tubes is used.


Assuntos
Centrifugação/instrumentação , Contenção de Riscos Biológicos , Segurança de Equipamentos , Técnicas Microbiológicas/instrumentação , Carga Bacteriana , Esporos Bacterianos/isolamento & purificação
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