An integrated microfluidic PCR system with immunomagnetic nanoparticles for the detection of bacterial pathogens

There is growing interest in rapid microbial pre-concentration methods to lower the detection limit of bacterial pathogens of low abundance in samples. Here, we report an integrated microfluidic PCR system that enables bacterial cells of interest in samples to be concentrated prior to PCR. It consists of two major compartments: a preconcentration chamber for the immunomagnetic separation of bacterial cells, and a PCR chamber for the DNA amplification of the concentrated cells. We demonstrate the feasibility of the system for the detection of microbial pathogens by preconcentrating the human pathogen Escherichia coli O157:H7, and also amplifying its DNA. The detection limit of E. coli O157:H7 in the PCR system is 1 × 10³ CFU (colony forming unit)/mL. On-chip processing steps, including preconcentration and PCR steps, take less than two hours. Our system can serve as a rapid, specific, and quantitative platform for the detection of microbial pathogens in samples of large volume.

TGF-β triggers rapid fibrillogenesis via a novel TβRII-dependent fibronectin-trafficking mechanism

There is increased recycling of soluble fibronectin from the cell surface for fibrillogenesis. This recycling is regulated by TGF-β in a transcription- and SMAD-independent manner via specific TβRII and integrin α5β1 interactions. The recycling of fibronectin is Rab11 dependent and is required for TGF-β–induced cell migration.

Fibronectin (FN) is a critical regulator of extracellular matrix (ECM) remodeling through its availability and stepwise polymerization for fibrillogenesis. Availability of FN is regulated by its synthesis and turnover, and fibrillogenesis is a multistep, integrin-dependent process essential for cell migration, proliferation, and tissue function. Transforming growth factor β (TGF-β) is an established regulator of ECM remodeling via transcriptional control of ECM proteins. Here we show that TGF-β, through increased FN trafficking in a transcription- and SMAD-independent manner, is a direct and rapid inducer of the fibrillogenesis required for TGF-β–induced cell migration. Whereas TGF-β signaling is dispensable for rapid fibrillogenesis, stable interactions between the cytoplasmic domain of the type II TGF-β receptor (TβRII) and the FN receptor (α5β1 integrin) are required. We find that, in response to TGF-β, cell surface–internalized FN is not degraded by the lysosome but instead undergoes recycling and incorporation into fibrils, a process dependent on TβRII. These findings are the first to show direct use of trafficked and recycled FN for fibrillogenesis, with a striking role for TGF-β in this process. Given the significant physiological consequences associated with FN availability and polymerization, our findings provide new insights into the regulation of fibrillogenesis for cellular homeostasis.

Empirical combination of a β-lactam to vancomycin may not improve outcomes of methicillin-susceptible Staphylococcus aureus bacteremia, compared to vancomycin monotherapy

To evaluate effect of empirical combination of a β-lactam to vancomycin and vancomycin monotherapy in Staphylococcus aureus bacteremia (MSSA-B), we conducted a retrospective cohort study. Electronic medical records of individuals who were diagnosed with MSSA-B between January 2005 and February 2015 at a tertiary care center were reviewed. Patients were classified into three groups according to empirical antibiotic regimen (BL group, β-lactam; VAN group, vancomycin; BV group, combination of β-lactam and vancomycin), and 30-day all-cause mortality of each group was compared. During the study period, 561 patients with MSSA-B were identified. After exclusion of 198 patients (36 with poly-microbial infection, 114 expired within 2 days, and 48 already received parenteral antibiotics) and a matching process, 46 patients for each group were included. Baseline characteristics were similar except for severity and comorbidity scores. The 30-day mortality for all three groups were not significantly different (BL 4.3%, VAN 6.5%, BV 8.7%; P = 0.909). In a multivariate analysis, type of empirical antibiotic regimen was not statistically associated with 30-day all-cause mortality. In comparison with the VAN group, the BV group yielded a HR of 0.579 (95% CI = 0.086-3.890, P = 0.574). Pitt bacteremia score was the only significant factor for mortality. The empirical combination of a β-lactam to vancomycin was not associated with lower mortality in treating MSSA-B, compared to vancomycin monotherapy.

Fabrication of a 3D Teflon microdevice for energy free homogeneous liquid flow inside a long microchannel and its application to continuous-flow PCR

The 3D spiral PTFE microdevice was fabricated for performing continuous-flow PCR using a single heater and via semi-automated sample injection method.

Thermally robust and biomolecule-friendly room-temperature bonding for the fabrication of elastomer-plastic hybrid microdevices

Here, we introduce a simple and fast method for bonding a poly(dimethylsiloxane) (PDMS) silicone elastomer to different plastics. In this technique, surface modification and subsequent bonding processes are performed at room temperature. Furthermore, only one chemical is needed, and no surface oxidation step is necessary prior to bonding. This bonding method is particularly suitable for encapsulating biomolecules that are sensitive to external stimuli, such as heat or plasma treatment, and for embedding fracturable materials prior to the bonding step. Microchannel-fabricated PDMS was first oxidized by plasma treatment and reacted with aminosilane by forming strong siloxane bonds (Si-O-Si) at room temperature. Without the surface oxidation of the amine-terminated PDMS and plastic, the two heterogeneous substrates were brought into intimate physical contact and left at room temperature. Subsequently, aminolysis occurred, leading to the generation of a permanent seal via the formation of robust urethane bonds after only 5 min of assembling. Using this method, large-area (10 × 10 cm) bonding was successfully realized. The surface was characterized by contact angle measurements and X-ray photoelectron spectroscopy (XPS) analyses, and the bonding strength was analyzed by performing peel, delamination, leak, and burst tests. The bond strength of the PDMS-polycarbonate (PC) assembly was approximately 409 ± 6.6 kPa, and the assembly withstood the injection of a tremendous amount of liquid with the per-minute injection volume exceeding 2000 times its total internal volume. The thermal stability of the bonded microdevice was confirmed by performing a chamber-type multiplex polymerase chain reaction (PCR) of two major foodborne pathogens - Escherichia coli O157:H7 and Salmonella typhimurium - and assessing the possibility for on-site direct detection of PCR amplicons. This bonding method demonstrated high potential for the stable construction of closed microfluidic systems socketed with biomolecule-immobilized surfaces such as DNA, antibody, enzyme, peptide, and protein microarrays.

Imprint Molding of a Microfluidic Optical Cell on Thermoplastics with Reduced Surface Roughness for the Detection of Copper Ions

Here, we introduce a simple and facile technique for fabricating microfluidic optical cells by utilizing a micropatterned polymer mold, followed by imprinting on thermoplastic substrates. This process has reduced the surface roughness of the microchannel, making it suitable for microscale optical measurements. The micropatterned polymer mold was fabricated by first micromilling on a poly(methylmethacrylate) (PMMA) substrate, and then transferring the micropattern onto an ultraviolet (UV)-curable optical adhesive. After an anti-adhesion treatment of the polymer mold fabricated using the UV-curable optical adhesive, the polymer mold was used repeatedly for imprinting onto various thermoplastics, such as PMMA, polycarbonate (PC), and poly(ethyleneterephthalate) (PET). The roughness values for the PMMA, PC, and PET microchannels were approximately 11.3, 20.3, and 14.2 nm, respectively, as compared to those obtained by micromilling alone, which were 15.9, 76.8, and 207.5 nm, respectively. Using the imprint-molded thermoplastic optical cell, rhodamine B and copper ions were successfully quantified. The reduced roughness of the microchannel surface resulted in improved sensitivity and reduced noise, paving the way for integration of the detection module so as to realize totally integrated microdevices.

Changes in the Microbial Composition of Microbrewed Beer during the Process in the Actual Manufacturing Line

This study investigated changes in the microbial composition of microbrewed beer during the manufacturing processes and identified potential microbial hazards, effective critical quality control points, and potential contamination routes. Comprehensive quantitative (aerobic plate count, lactic acid bacteria, fungi, acetic acid bacteria, coliforms, and Bacillus cereus) and qualitative (Escherichia coli and eight foodborne pathogens) microbiological analyses were performed using samples of raw materials (malt and manufacturing water), semiprocessed products (saccharified wort, boiled wort, and samples taken during the fermentation and maturation process), and the final product obtained from three plants. The initial aerobic plate count and lactic acid bacteria counts in malt were 5.2 and 4.3 log CFU/g, respectively. These counts were reduced to undetectable levels by boiling but were present at 2.9 and 0.9 log CFU/ml in the final product. Fungi were initially present at 3.6 log CFU/g, although again, the microbes were eliminated by boiling; however, the level in the final product was 4.6 log CFU/ml. No E. coli or foodborne pathogens (except B. cereus) were detected. B. cereus was detected at all stages, although it was not present in the water or boiled wort (total detection rate ¼ 16.4%). Results suggest that boiling of the wort is an effective microbial control measure, but careful management of raw materials and implementation of effective control measures after boiling are needed to prevent contamination of the product after the boiling step. The results of this study may constitute useful and comprehensive information regarding the microbiological quality of microbrewed beer.

Instantaneous room temperature bonding of a wide range of non-silicon substrates with poly(dimethylsiloxane) (PDMS) elastomer mediated by a mercaptosilane

This paper introduces an instantaneous and robust strategy for bonding a variety of non-silicon substrates such as thermoplastics, metals, an alloy, and ceramics to poly(dimethylsiloxane) (PDMS) irreversibly, mediated by one-step chemical modification using a mercaptosilane at room temperature followed by corona treatment to realize heterogeneous assembly also at room temperature. The mercapto functional group is one of the strongest nucleophiles, and it can instantaneously react with electrophiles of substrates, resulting in an alkoxysilane-terminated substrate at room temperature. In this way, prior oxidation of the substrate is dispensed with, and the alkoxysilane-terminated substrate can be readily oxidized and irreversibly bonded with oxidized PDMS at room temperature. A commercially available Tesla coil was used for surface oxidation, replacing a bulky and expensive plasma generator. Surface characterization was conducted by water contact angle measurement and X-ray photoelectron spectroscopy (XPS) analysis. A total of fifteen non-silicon substrates including polycarbonate (PC), two types of poly(vinylchloride) (PVC), poly(methylmethacrylate) (PMMA), polystyrene (PS), polyimide (PI), two types of poly(ethylene terephthalate) (PET), polypropylene (PP), iron (Fe), aluminum (Al), copper (Cu), brass, alumina (Al2O3), and zirconia (ZrO2) were bonded successfully with PDMS using this method, and the bond strengths of PDMS-PMMA, PDMS-PC, PDMS-PVC, PDMS-PET, PDMS-Al, and PDMS-Cu assemblies were measured to be approximately 335.9, 511.4, 467.3, 476.4, 282.2, and 236.7 kPa, respectively. The overall processes including surface modification followed by surface oxidation using corona treatment for bonding were realized within 12 to 17 min for most of the substrates tested except for ceramics which required 1 h for the bonding. In addition, large area (10 × 10 cm(2)) bonding was also successfully realized, ensuring the high reliability and stability of the introduced method.

Non-photolithographic plastic-mold-based fabrication of cylindrical and multi-tiered poly(dimethylsiloxane) microchannels for biomimetic lab-on-a-chip applications

Cylindrical and multi-tiered PDMS microchannels were fabricated from two thermoplastic molds having large difference in glass transition temperatures, and were used for constructing LOC platforms mimicking human microvasculature and liver sinusoid.

Portable plastic syringe as a self-actuated pump for long-distance uniform delivery of liquid inside a microchannel and its application for flow-through polymerase chain reaction on chip

A strategy for realizing self-actuated pumping with uniform flow rate over a long distance is introduced using hands-on operation of disposable syringe, and was applied for on-chip flow-through PCR inside a serpentine PMMA microchannel.

Flow-through polymerase chain reaction inside a seamless 3D helical microreactor fabricated utilizing a silicone tube and a paraffin mold

Seamless 3D helical silicone tube microreactors were fabricated for performing flow-through PCR employing a single hot plate and a portable micropump.

Clinical characteristics of Raoultella ornithinolytica bacteremia

PURPOSE

Raoultella ornithinolytica is not well known as a clinical pathogen. We performed a retrospective review of R. ornithinolytica bacteremia to investigate its clinical features, antimicrobial susceptibility, and overall patient outcomes.

METHODS

R. ornithinolytica bacteremia cases were collected from an electronic database of all cases of bacteremia over a 10-year period. Medical records were retrospectively reviewed. Demographic data, clinical information, the presence of underlying comorbidities, the results of antimicrobial susceptibility testing, and the antimicrobial regimen administered were investigated.

RESULTS

R. ornithinolytica was isolated from blood culture specimens in 16 cases. The majority of these patients had an underlying malignant condition of advanced stage (15 patients, 94 %). Seven of these patients had a solid tumor with lesions or metastases that extended to the bile duct or biliary tract. Neutropenic fever following hematologic stem cell transplantation was found in three cases. No resistance to piperacillin/tazobactam or imipenem was found. Four cases showed resistance to cefoxitin, while one of these cases showed resistance to multiple cephalosporins. In overall outcomes, seven patients (44 %) did not recover from the infection and subsequently expired.

CONCLUSIONS

R. ornithinolytica bacteremia occurs mainly in patients with underlying malignancies. The overall outcome was not favorable, despite favorable antimicrobial susceptibility test results. The findings of this study contradict those of other studies that demonstrated that infection from Raoultella species have good prognoses.

Transparent, low-power pressure sensor matrix based on coplanar-gate graphene transistors

A novel device architecture for preparing a transparent and low-voltage graphene pressure-sensor matrix on plastic and rubber substrates is demonstrated. The coplanar gate configuration of the graphene transistor enables a simplified procedure. The resulting devices exhibit excellent device performance, including a high transparency of ca. 80% in the visible range, a low operating voltage less than 2 V, a high pressure sensitivity of 0.12 kPa(-1) , and excellent mechanical durability over 2500 cycles.

One-step surface modification for irreversible bonding of various plastics with a poly(dimethylsiloxane) elastomer at room temperature

Here, we introduce a simple and facile method for bonding poly(dimethylsiloxane) (PDMS) to various plastics irreversibly via a one-step chemical treatment at room temperature. This was mediated by poly[dimethylsiloxane-co-(3-aminopropyl)methylsiloxane] (amine-PDMS linker), a chemical composed of a PDMS backbone incorporating an amine side group. Room temperature anchoring of the linker was achieved via a reaction between the amine functionality of the linker and the carbon backbone of the plastics, thereby producing urethane bonds. This resulted in the PDMS functionality being exposed on the plastic surface, mimicking the surface properties of bulk PDMS. Following corona treatment of the PDMS-modified plastic and a sheet of PDMS, the two surfaces were placed in contact with each other and heated at 80 °C for 1 h. This resulted in permanent bonding between PDMS and the plastic. To examine the effectiveness of the amine-PDMS linker coating procedure, the surfaces were characterized by measuring water contact angles and by employing X-ray photoelectron spectroscopy (XPS). Polycarbonate (PC), poly(ethylene terephthalate) (PET), poly(vinylchloride) (PVC), and polyimide (PI) were bonded successfully to PDMS using this method, with bond strengths of PC, PET, and PVC with PDMS measured to be approximately 428.5 ± 17.9, 361.7 ± 31.2, and 430.0 ± 14.9 kPa, respectively. The bond strength of a PC-PC homogeneous assembly, also realized using the proposed method, was measured to be approximately 343.9 ± 7.4 kPa. Delamination tests revealed that the PC-PC assembly was able to withstand intense introduction of a liquid whose per-minute injection volume was approximately 278 times greater than the total internal volume of the microchannel fabricated in PC. This demonstrated the robustness of the seal formed using the proposed technique.

The evaluation of combined chemical and physical treatments on the reduction of resident microorganisms and Salmonella Typhimurium attached to chicken skin

This study was conducted to evaluate the efficacy of sodium hypochlorite (NaOCl, 0-200 mg/kg), thiamine dilauryl sulfate (TDS, 1,000 mg/kg), and ultrasound (37 kHz, 380 W) on reducing Salmonella Typhimurim, mesophilic aerobic bacteria (MAB), and coliforms on chicken skin. Chemical and physical treatments were applied for 5 min either singly or jointly, and Salmonella previously inoculated on chicken skin were quantitatively assessed using brilliant green agar, and the populations of MAB and coliforms in the native flora were enumerated using plate count agar and violet red bile agar, respectively. In the evaluation of bacterial attachment/detachment, chicken skin was quantitatively assessed for loosely, intermediately, and tightly attached bacteria. The treatment effects on bacteria detachment were also visualized using field emission scanning electron microscopy. In addition, color and textural properties of the skin after treatments were evaluated using a color difference meter and texture analyzer. Antimicrobial activity of NaOCl increased as the NaOCl concentration was increased, especially for loosely attached cells. The combination of 200 mg/kg NaOCl and ultrasound (NaOCl/ultrasound) significant reduced loosely, intermediately, and tightly attached bacteria populations by 0.75 to 0.47, 0.43 to 0.41, and 0.83 to 0.54 log cfu/g for MAB, coliforms, and Salmonella Typhimurium, respectively. However, the combination of NaOCl and TDS (NaOCl/TDS) did not sufficiently reduce those cells on chicken skins, except for loosely attached MAB and coliforms. The NaOCl/ultrasound combination produced a higher reduction in numbers of inoculated and native bacteria flora than any single application, with no negative effect on skin color or texture. Generally, the loosely attached bacteria were less resistant to the chemical and physical treatments than the intermediately and tightly attached bacteria in chicken skin, presumably due to their location in deeper skin layer and crevices. Further research is needed to investigate how the intermediately and tightly attached microorganisms can be effectively eliminated from chicken skin.

Phase I study of weekly nab-paclitaxel + weekly cetuximab + intensity-modulated radiation therapy (IMRT) in patients with stage III-IVB head and neck squamous cell carcinoma (HNSCC)

BACKGROUND

There is a clinical need to improve the efficacy of standard cetuximab + concurrent intensity-modulated radiation therapy (IMRT) for patients with locally and/or regionally advanced HNSCC. Taxanes have radiosensitizing activity against HNSCC, and nab-paclitaxel may offer therapeutic advantage in comparison with other taxanes.

PATIENTS AND METHODS

This was a single-institution phase I study with a modified 3 + 3 design. Four dose levels (DLs) of weekly nab-paclitaxel were explored (30, 45, 60, and 80 mg/m(2)), given with standard weekly cetuximab (450 mg/m(2) loading dose followed by 250 mg/m(2) weekly) and concurrent IMRT (total dose, 70 Gy).

RESULTS

Twenty-five eligible patients (20 M, 5 F) enrolled, with median age 58 years (range, 46-84 years). Primary tumor sites were oropharynx, 19 (10 human papillomavirus [HPV] pos, 8 HPV neg, 1 not done); neck node with unknown primary, 2; larynx 2; and oral cavity and maxillary sinus, 1 each. Seven patients had received prior induction chemotherapy. Maximum tolerated dose (MTD) was exceeded at DL4 (nab-paclitaxel, 80 mg/m(2)) with three dose-limiting toxicities (DLTs) (grade 3 neuropathy, grade 3 dehydration, with grade 3 mucositis grade 3 anemia) among five assessable patients. There was only one DLT (grade 3 supraventricular tachycardia) among six patients at DL3 (nab-paclitaxel, 60 mg/m(2)), and this was deemed the MTD. Among 23 assessable patients, the most common ≥ g3 AEs were lymphopenia 100%, functional mucositis 65%, and pain in throat/oral cavity 52%. At a median follow-up of 33 months, 2-year failure-free survival (FFS) is 65% [95% confidence interval (CI) 42% to 81%] and 2-year overall survival (OS) is 91% (95% CI 69-97).

CONCLUSION

The recommended phase II dose for nab-paclitaxel is 60 mg/m(2) weekly when given standard weekly cetuximab and concurrent IMRT. This regimen merits further study as a nonplatinum alternative to IMRT + cetuximab alone.

CLINICALTRIALSGOV ID

NCT00736619.

An alternative local anaesthesia technique to reduce pain in paediatric patients during needle insertion

AIM

Pain control, which is necessary during most dental procedures, is administered by injecting a local anaesthetic. Because the injection itself can be painful, the procedure via which pain is reduced warrants continued investigation. Only a few studies regarding the reaction of children to dental needle insertion without the use of topical anaesthetics have been reported. This study was conducted to evaluate the efficacy of the local anaesthetic procedure without topical application as compared to the conventional insertion technique for alleviating pain in children receiving local anaesthesia injections.

MATERIALS AND METHODS

For the alternative injection procedure, the dentist quickly and gently pulled or pushed the clean and dried loose tissue at the injection site over the tip of the needle to a depth of 1 to 1.5 mm. When the end of the bevel of the needle tip entered the tissue, a few drops of solution were released, after which the needle was advanced to its proper and intended depth to continue anaesthetic release.

RESULTS

There was a significant difference regarding the pain response between the alternative insertion technique (less painful) and the conventional one according to Sound, Eye, and Motor (SEM) scale ratings (P < 0.000). No significant difference was observed in the response between the maxilla and mandible, nor between boys and girls, between the conventional and alternative techniques.

CONCLUSION

This alternative technique can reduce discomfort in paediatric dental patients and allow the clinician to administer a superficial local anaesthesia injection before the needle is advanced into deeper tissue. This technique is simple, quick, devoid of additional costs, and potentially more effective than the conventional needle insertion method.

A rotary microsystem for simple, rapid and automatic RNA purification

In this work, we demonstrate a novel rotary microsystem for simple, rapid and automatic influenza viral RNA purification. The microdevice consists of a silica sol-gel matrix for RNA capture, and three reservoirs for a RNA sample (R(S)), a washing solution (R(W)) and an elution buffer (R(E)) that were connected with different dimensional microfluidic channels (120 μm for R(S), 40 μm for R(W), and 20 μm for R(E)). The hydrophobic property of PDMS and the narrow microchannel served as a passive capillary microvalve, and the loading of the solutions were controlled by centrifugal force. 5 μL of a lysate sample of influenza A H1N1 virus, a washing solution and an elution buffer were injected in each designated reservoir, and the virus sample, the washing solution, and the elution buffer were sequentially loaded into the sol-gel chamber at 1600, 2000, and 2500 RPM, enabling the viral RNA to be captured in the sol-gel solid phase, purified, and eluted in 5 min. The RNA capture yield was measured as ~80%, and the H1 and M gene were successfully amplified from the recovered purified H1N1 viral RNA by reverse-transcriptase PCR. Such a novel rotary sample preparation system eliminates any complicated hardware and human intervention, and performs the RNA extraction with high speed and high fidelity.

Excretory-secretory products of Giardia lamblia induce interleukin-8 production in human colonic cells via activation of p38, ERK1/2, NF-κB and AP-1

Giardia lamblia, a pathogen causing diarrhoeal outbreaks, is interesting how it triggers immune response in the human epithelial cells. This study defined the crucial roles of signalling components involved in G. lamblia-induced cytokine production in human epithelial cells. Incubation of the gastrointestinal cell line HT-29 with G. lamblia GS trophozoites triggered production of interleukin (IL)-1β, IL-8 and tumour necrosis factor (TNF)-α. IL-8 production was not significantly decreased by physically separating the HT-29 cells and G. lamblia GS trophozoites. Indeed, treatment of HT-29 with G. lamblia excretory-secretory products (ESP) induced IL-8 production. Electrophoretic mobility gel shift and transfection assays using mutagenized IL-8 promoter reporter plasmids indicated that IL-8 production by G. lamblia ESP occurs through activation of two transcriptional factors, nuclear factor kappaB (NF-κB) and activator protein 1 (AP-1) in HT-29 cells. In addition, activation of two mitogen-activated protein kinases (MAPKs), p38 and ERK1/2, was also detected in the HT-29 cells stimulated with G. lamblia ESP. Selective inhibition of these MAPKs resulted in decreased production of ESP-induced IL-8. These results indicate that activation of p38, ERK1/2 MAPK, NF-κB and AP-1 comprises the signalling pathway responsible for IL-8 production by G. lamblia ESP.