Reproducible bubble-induced acoustic microstreaming for bead disaggregation and immunoassay in microfluidics

The bead-based immunoassay requires not only efficient mixing but also good control of bead-surface-area-to-sample-volume ratio to realise accurate and reproducible detection of low concentration samples. This paper reports the development of a microfluidic platform with the reproducible and efficient bubble-induced micromixing for bead disaggregation and immunoassay of prostate-specific antigen (PSA). The platform consists of a microfluidic chip with a microchamber and rectangular traps for capturing air bubbles and a home-made controller to generate sound wave using an external piezo transducer. Methods for reproducible bubble formation and bubble size control during mixing are explored. The influence of driving voltage, PDMS thickness and the substrate material on the mixing efficiency is characterised by mixing a fluorescence dye and a buffer solution. The optimised acoustic microstreaming is able to break clusters with hundreds of beads and homogenise individual beads over the microchamber. Immunoassay with efficient micromixing has been applied to PSA immunoassay with greatly reduced detection time. This study provides a practical guide for the design and development of the bubble-induced acoustic micromixers for bead disaggregation and on-chip immunoassays

Making a hydrophoretic focuser tunable using a diaphragm

Microfluidic diagnostic devices often require handling particles or cells with different sizes. In this investigation, a tunable hydrophoretic device was developed which consists of a polydimethylsiloxane (PDMS) slab with hydrophoretic channel, a PDMS diaphragm with pressure channel, and a glass slide. The height of the hydrophoretic channel can be tuned simply and reliably by deforming the elastomeric diaphragm with pressure applied on the pressure channel. This operation allows the device to have a large operating range where different particles and complex biological samples can be processed. The focusing performance of this device was tested using blood cells that varied in shape and size. The hydrophoretic channel had a large cross section which enabled a throughput capability for cell focusing of ∼15 000 cells s−1, which was more than the conventional hydrophoretic focusing and dielectrophoresis (DEP)-active hydrophoretic methods. This tunable hydrophoretic focuser can potentially be integrated into advanced lab-on-a-chip bioanalysis devices

Development of a novel magnetophoresis-assisted hydrophoresis microdevice for rapid particle ordering

Focusing and ordering of micro- or nanoparticles is an essential ability in microfluidic platforms for bio-sample processing. Hydrophoresis is an effective method utilising hydrodynamic force to focus microparticles, but it is limited by the fixed operational range and the lack of flexibility. Here, we report a work to tune and improve the dynamic range of hydrophoresis device using magnetophoresis. In this work, a novel approach was presented to fabricate the lateral fluidic ports, which allow the flipped chip to remain stable on the stage of microscope. Diamagnetic polystyrene microparticles suspended in a ferrofluidic medium were repelled to the lower level of the channel by negative magnetophoretic force, and then interact with grooves of microchannel to obtain an excellent hydrophoretic ordering. The effects of (i) flow rate, (ii) particle size, (iii) magnetic susceptibility of the medium, and (iv) number of magnets on the particle focusing efficiency were also reported. As the proposed magnetophorsis-assisted hydrophoretic device is tuneable and simple, it holds great potential to be integrated with other microfluidic components to form an integrated sample-to-answer system

Significance of Methylation of FBP1 Gene in Non-Small Cell Lung Cancer

Because NSCLC has poor overall prognosis and is frequently diagnosed at later stage, we aimed to seek novel diagnosis biomarkers or therapy target of the disease in this study. Fructose-1,6-bisphosphatase 1 (FBP1) is a rate-limiting enzyme in gluconeogenesis, which was usually lost in NSCLC due to abnormal methylation in promoter DNA sequence. The clinical data indicated that the methylation rate in FBP1 gene promoter was negatively related to the overall survival of the NSCLC patients. DNA methylation transferase inhibitor 5-aza treatment could significantly increase both expression levels of mRNA and protein in A549 cell line. On the other hand, silence of FBP1 in H460 cell line by using specific siRNA against FBP1 dramatically improved the cell proliferation and cell migration according to the date of FACS and transwell assays. All these findings implied the important roles of FBP1 expression in lung cancer development and progression and the potential use of the methylation status detected in FBP1 promoter region as a novel predictor for prognosis and therapeutic target for NSCLC patients

Risk Factor Analysis of Calcification in Aortic and Mitral Valves in Maintenance Peritoneal Dialysis Patients

Background/Aims: This study aimed to investigate potential risk factors for calcification in aortic and mitral valves in maintenance peritoneal dialysis (MPD) patients. Methods: We enrolled MPD patients who had undergone over 18 months of dialysis in our dialysis center, examined their cardiac valve calcification status by echocardiography, and recorded their biochemical data and dialysis-related indicators. These results were compared by logistic regression analyses to identify the risk factors associated with calcification in aortic and mitral valves. Results: Among the 117 enrolled MPD patients, 41 exhibited calcification in aortic or mitral valves, including 38 with aortic valve calcification (AVC) and 17 with mitral valve calcification (MVC); 14 of them had calcification in both aortic and mitral valves. Multivariate logistic regression analysis revealed that age (OR=1.965, p=0.01), diabetes history (OR=4.693, p=0.029), calcium-phosphorus product (OR=2.373, p=0.001) and prealbumin (OR=0.908, p=0.012) were independently related to AVC, whereas age (OR=3.179, p=0.023), calcium-phosphorus product (OR=6.512, p=0.001), prealbumin (OR=0.885, p=0.033), high-density lipoprotein (OR=19.540, p=0.011) and diabetes history (OR=6.948, p=0.038) were independently related to MVC. Conclusions The incidence of cardiac valve calcification in MPD patients is high, and the incidence of AVC is higher than MVC. Age, diabetes history, calcium-phosphorus product and hypo-prealbuminemia are independent risk factors for AVC, whereas age, calcium-phosphorus product and hypo-prealbuminemia are independent risk factors for MVC

Early Peritonitis is an Independent Risk Factor for Mortality in Elderly Peritoneal Dialysis Patients

Background/Aims: The impact of early peritonitis on the outcome of elderly peritoneal dialysis (PD) patients has not been studied. We aimed to research the influence of early peritonitis on patient outcomes in elderly PD patients. Methods: This study involved elderly PD patients (age ≥65) who underwent PD between Jan 1, 2004 and Jul 31, 2013. Patient characteristics were collected in our database. Early peritonitis was defined as peritonitis within 6 months after the initiation of PD. Patient survival and technique were compared among the non-peritonitis, early peritonitis and late peritonitis groups using Cox regression analysis. Results: There were 155 subjects involved in this study. The patients were divided among a non-peritonitis group (n=78), early peritonitis group (n=32) and late peritonitis group (n=45). The organisms causing first peritonitis in the two groups did not differ significantly. After adjustment for age, diabetes, serum albumin and residual renal function, multivariable Cox regression model revealed that compared with the early peritonitis group, both the non-peritonitis group (HR 0.57, RI 0.32-0.99, p=0.046) and the late peritonitis group (HR 0.37, RI 0.16-0.75, p=0.004) exhibited a lower patient mortality rate. Conclusions: Early peritonitis is an independent risk factor for mortality in elderly peritoneal dialysis patients

Uric Acid Levels and All-Cause Mortality in Peritoneal Dialysis Patients

Background: Epidemiological studies have shown that hyperuricemia is associated with all-cause and cardiovascular mortality in chronic kidney disease (CKD) and hemodialysis patients. Our study investigated the influence of serum uric acid (UA) levels on survival in peritoneal dialysis (PD) patients. Methods: This was a retrospective study involving 156 subjects who had undergone PD. The patient demographics, etiology of ESRD, comorbid conditions and other laboratory parameters were collected. The subjects were divided into three groups according to their serum UA concentrations (group 1, the lowest quartile; group 2, the middle quartiles; group 3, the highest quartile). The risk of death was calculated using a multivariate Cox regression model. Results: There were 41 deaths during a follow-up period of 31.3±17.5 months. Compared with group 2, which had a mortality rate of 5.7 per 1000 person-months, the mortality rates were higher in group 1 (14.3 per 1000 person-months, p0.05) for group 1 and 2.96 (95% CI 1.29-6.80, p=0.01) for group 3. Conclusions: In PD patients, a higher serum UA level is related to increased mortality and is an independent risk factor for all-cause mortality. Uric acid levels and all-cause mortality in peritoneal dialysis patients

Outcomes of elderly peritoneal dialysis patients: 65–74 years old versus ≥ 75 years old

AbstractObjective To analyze the clinical data of elderly patients with peritoneal dialysis (PD) and compare patient and technique survival rates between Group 1 (65–74 years old) and Group 2 (≥75 years old).Methods This retrospective study enrolled 296 elderly patients (≥65 years old) on maintenance PD who were admitted to the Peritoneal Dialysis Center of the Second Hospital of Soochow University. The patients were categorized by outcome into ongoing PD, changed to hemodialysis, renal recovery dialysis stopped, or death groups. The patients were divided into Group 1 (65–74 years old) and Group 2 (≥75 years old). Patient survival and technique survival rates were calculated by the Kaplan–Meier method. Factors associated with patient survival were analyzed using the Cox regression model.Results There were 176 (59.5%) subjects in Group 1 and 120 (40.5%) subjects in Group 2. The primary causes of death were cardiovascular events, peritonitis, and other infections. The patient survival rates at 1, 3, and 5 years were 91.2%, 68.0%, and 51.3% in Group 1 and 76.8%, 37.5%, and 17.6% in Group 2 (p < 0.001, HR 0.387, 95% CI 0.282–0.530). There was no statistically significant difference in the technique survival rate between the two groups (p = 0.54).Conclusion The elderly PD patients in this cohort mostly died from cardiovascular events, with a higher patient survival rate in Group 1 and similar technique survival in both groups. Older age, lower prealbumin, higher creatinine, not being on activated vitamin D, and high Charlson’s comorbidity index (CCI) score were independent risk factors for death