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Article in Chinese | WPRIM | ID: wpr-928207


Cell migration is defined as the directional movement of cells toward a specific chemical concentration gradient, which plays a crucial role in embryo development, wound healing and tumor metastasis. However, current research methods showed low flux and are only suitable for single-factor assessment, and it was difficult to comprehensively consider the effects of other parameters such as different concentration gradients on cell migration behavior. In this paper, a four-channel microfluidic chip was designed. Its characteristics were as follows: it relied on laminar flow and diffusion mechanisms to establish and maintain a concentration gradient; it was suitable for observation of cell migration in different concentration gradient environment under a single microscope field; four cell isolation zones (20 μm width) were integrated into the microfluidic device to calibrate the initial cell position, which ensured the accuracy of the experimental results. In particular, we used COMSOL Multiphysics software to simulate the structure of the chip, which demonstrated the necessity of designing S-shaped microchannel and horizontal pressure balance channel to maintain concentration gradient. Finally, neutrophils were incubated with advanced glycation end products (AGEs, 0, 0.2, 0.5, 1.0 μmol·L -1), which were closely related to diabetes mellitus and its complications. The migration behavior of incubated neutrophils was studied in the 100 nmol·L -1 of chemokine (N-formylmethionyl-leucyl-phenyl-alanine) concentration gradient. The results prove the reliability and practicability of the microfluidic chip.

Cell Movement , Chemotaxis , Equipment Design , Lab-On-A-Chip Devices , Microfluidic Analytical Techniques , Microfluidics , Neutrophils , Reproducibility of Results
Acta Pharmaceutica Sinica ; (12): 323-329, 2020.
Article in Chinese | WPRIM | ID: wpr-789033


Drug screening against Candida albicans has become more urgent due to the increasing incidence of infection and the development of drug-resistant strains. The microfluidic chip technique has shown great potential for high-throughput drug screening. In this study we developed a concentration gradient microfluidic chip platform for drug screening against Candida albicans. The generated concentration gradient on this platform was investigated qualitatively by monitoring the distribution of the fluorescent tracer fluorescein sodium and quantitatively by following the distribution of the model drug fluconazole as analyzed by HPLC; the effect of different flow conditions on the concentration gradient were determined. The ratio of the two aqueous phase flow rates was determined in the subsequent drug screening studies. Alamar Blue, an indicator of cell viability, was used in the susceptibility test for amphotericin B, fluconazole, itraconazole, voriconazole, posaconazole, terbinafine, 5-fluorocytosine and caspofungin as carried out on the established chip platform. The MIC range of the drugs, which was consistent with the MIC values of the CLSI-recommended standard, were obtained quickly and efficiently through the use of this platform, indicating that this new platform can quickly screen a series of antibacterial drugs in one run. In addition, the strain of Candida albicans we used showed resistance to terbinafine in our platform assay, consistent with the results of a 96-well plate assay, indicating that the platform can also be used for rapid screening of resistant strains.

Article in English | WPRIM | ID: wpr-716523


BACKGROUND: Pen-based devices have emerged as useful tools for measuring pH and glucose, and for fabricating microchannels and microarrays. Pen-based devices take advantage of flexible patterning, inexpensive costs, and small volumes, thereby saving time and increasing efficiency. We have developed a gradient nib marker pen device that generated simultaneously different antibiotic concentrations in bacteria antibiotic susceptibility testing (AST). METHODS: The device can deposit on the target surface with the antibiotic gradient. The designed polyester fiber nibs are a highly uniform porosity with unidirectional orientation and produce a visible gradient pattern. RESULTS: We have demonstrated and quantitatively analyzed bacterial growth after antibiotic marking. The antibiotic marking produces an inhibition zone of bacterial growth. The inhibition zones of bacterial growth are captured and converted to 8-bit grayscale images, and then quantified by gray values using the Image J program. A profile of the inhibition zone showed different gray values in response to bacterial viability. CONCLUSION: The gradient nib marker pen device can be used to determine the quantitative antibiotic concentration based on the relationship between gray values and bacterial density conveniently without requiring a series of dilution tubes, including nutrient medium, and diversely diluted antibiotics.

Anti-Bacterial Agents , Bacteria , Clothing , Glucose , Hydrogen-Ion Concentration , Microbial Viability , Polyesters , Porosity
Salus ; 17(supl.1): 29-38, dic. 2013. ilus, tab
Article in Spanish | LILACS-Express | LILACS | ID: lil-710672


El Blastocystis sp es un protozoario con alta prevalencia en Venezuela. Es controversial por su papel patógeno y su gran variabilidad genética, relacionada con la dificultad de mantenerlo en condiciones de viabilidad fuera del hospedador. Se evaluó la utilidad de los medios de cultivo in vitro RPMI1640, TB1, MBD y MBDM para mantener la viabilidad del Blastocystis sp. Se seleccionaron 97 muestras de heces, 43 (44%) de las cuales resultaron positivas solo para Blastocystis sp y de 15 de ellas se purificaron los Blastocystis sp mediante gradiente (ficol-diatrizaoato de sodio). En cada medio de cultivo y en solución salina 0,85% (SSI) se inoculó1x103 parásitos por paciente y se evaluó la viabilidad mediante coloración con azul de tripano a las 24, 48 y 72 horas. Los resultados mostraron porcentajes de viabilidad a las 24 h: en SSI de 2%, en RPMI1640 5%, en TB1 5%, MBD 24% y MBDM 40%. A las 48 h: en SSI de 3%, en RPMI1640 4%, en TB1 4%, MBD 17% y MBDM 21%. A las 72 h: en SSI 2%, en RPMI1640 2%, en TB1 2%, MBD 15% y MBDM 16%. Se observaron diferencias estadísticamente significativas después de las 24 h, entre los medios TB1, MBD y MBDM comparado con SSI. Se concluye que el medio MBDM es el que ofrece las mejores condiciones para mantener viable a Blastocystis sp por 72 h.

The protozoan Blastocystis sp is a high prevalence in Venezuela. Its role is controversial pathogen and its wide genetic variability related to the difficulty of keeping it in a position outside the host viability. We evaluated the utility of in vitro culture media RPMI1640, TB1, and MBDM MBD to maintain the vitality of Blastocystis sp. They selected 97 stool samples, 43 (44%) of which were positive for Blastocystis sp and only 15 of them were purified by gradient Blastocystis sp (ficoll-sodium diatrizaoato). In each culture medium and 0.85% saline (SSI) is inoculó1x103 parasites per patient and viability was assessed by trypan blue staining after 24, 48 and 72 hours. The results showed viability percentage at 24 hours: in SSI of 2%, 5% RPMI1640 at TB1 5%, 24% and MBDM MBD 40%. After 48 h: SSI 3% in RPMI1640 4%, 4% TB1, MBD MBDM 17% and 21%. After 72 h: SSI 2% in RPMI1640 2%, 2% TB1, MBD 15% and 16% MBDM. Statistically significant differences were observed after 24 h, between TB1 media, compared MBDM MBD and SSI. We conclude that the medium is MBDM which offers the best conditions for maintaining viable Blastocystis sp for 72 h.

Journal of Medical Biomechanics ; (6): E335-E340, 2011.
Article in Chinese | WPRIM | ID: wpr-804159


Objective To develop a microfluidic device with the adjustable concentration and pressure gradient for 3D cell culture in hydrogel and set up an in vitro model with the capability to closely simulate in vivo microenvironment for cell growth. Methods The microfluidic chip, with a middle channel for 3D cell culture and two side channels for delivering cell culture medium, was designed and fabricated using standard soft lithography and replica molding techniques. Its capability to generate concentration gradient, interstitial flow and image cell in situ was demonstrated. Results A simple microfluidic chip for 3D cell culture in hydrogel with the capability to generate the concentration and pressure gradient was obtained. At a flow rate of 2 μL•min-1 in each side channel, the concentration gradients remained constant after 3 h. The interstitial flow across the gel scaffold was generated by a 100 Pa pressure difference between two-side channels with the pressure gradient of 0.11 Pa/μm. Human adult dermal microvascular endothelial cells (HMVEC) were maintained in 3D culture with collagen type I and observed with confocal microscopy. Conclusions The microfluidic chip is simple and easy to operate and it can simulate the complicated microenvironment in vivo. The chip also allows the multiparameter control of microenvironment, facilitating the better understanding of interaction between cells and microenvironment.

Article in English | WPRIM | ID: wpr-118160


Chronic stable diabetic patients (n = 6) were compared with healthy control subjects (n = 5) after acute oral intake of 50 mEq of potassium chloride (KCl) to investigate for possible derangements of homeostatic responses for acute term (3 hrs) to acute potassium load. Plasma renin activity (PRA), plasma aldosterone (PA), and transtubular potassium concentration gradient (TTKG) known as a useful semiquantative index of distal nephron potassium secretion were measured. All the baseline parameters were comparable between diabetic and non-diabetic subjects except for significantly reduced creatinine clearance in diabetics (mean +/- SEM, 105 +/- 4 vs. 85 +/- 5 ml/min, p 5.0 mEq/L). PRA did not show any significant changes, whereas PA was increased simultaneously with increments in serum potassium in both groups, with blunted increases in the diabetics. However, TTKG was increased prominently in control subjects (8.18 from 4.98), but only slightly in diabetic subjects (4.55 from 4.18), with statistical difference between the two groups (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult , Aged , Aldosterone/blood , Diabetes Mellitus, Type 2/metabolism , Homeostasis , Humans , Kidney Tubules/metabolism , Male , Middle Aged , Potassium/metabolism , Renin/blood