Microscopic resection of lumbar intraspinal tumor through keyhole approach: A clinical study of 54 cases / 北京大学学报(医学版)

OBJECTIVE@#To explore the feasibility and key technology of microscopic resection of lumbar intraspinal tumor through microchannel keyhole approach.@*METHODS@#The clinical features, imaging characteristics and surgical methods of 54 cases of lumbar intraspinal tumor which were microscopically operated by microchannel from February 2017 to September 2019 were reviewed and analyzed. There were 8 cases of extradural tumor, 3 cases of extra-and intradural tumor and 43 cases of subdural extramedullary tumor (including 3 cases of ventral spinal tumor). The tumors were 0.5-3.0 cm in diameter. The clinical symptoms included 49 cases of pain in the corresponding innervation area, 5 cases of sensory disturbance (numbness) at or below the tumor segment, 7 cases of limb weakness and 2 cases of urination and defecation dysfunction.@*RESULTS@#In the study, 37 tumors were resected through hemilaminectomy, 14 tumors were resected through interlaminar fenestration, 3 tumors were resected through hemilaminectomy or interlaminar fenestration combined with facetectomy of medial 1/4 facet. All of the 54 tumors were totally resected. The operation time was 75-135 min, with an average of 93.3 min. The postoperative hospital stay was 4-7 days, with an average of 5.7 days. Postoperative pathology included 34 cases of schwannoma, 4 cases of meningioma, 9 cases of ependymoma, 1 case of enterogenous cyst, 5 cases of teratoma/epidermoid/dermoid cyst, and 1 case of paraganglioma. No infection or cerebrospinal fluid leakage was found after operation. No neurological dysfunction occurred except 1 case of urination dysfunction and 4 cases of limb numbness. The follow-up period ranged from 3 to 33 months with an average of 14.4 months. Five patients with new onset symptoms returned to normal. The pain symptoms of 49 patients were completely relieved; 4 of 5 patients with hypoesthesia recovered completely, the other 1 patient had residual mild hypoesthesia; 7 patients with limb weakness, and 2 patients with urination and defecation dysfunction recovered to normal. No spinal instability or deformity was found, and no recurrence or residual tumors were found. According to McCormick classification, they were of all grade Ⅰ.@*CONCLUSION@#The lumbar intraspinal extramedullary tumors within two segments (including the ventral spinal tumors) can be totally resected at stage Ⅰ through microchannel keyhole approach with appropriate selection of the cases. Microchannel technique is beneficial to preserve the normal structure and muscle attachment of lumbar spine, and to maintain the integrity and stability of lumbar spine.

Influencing factors and evaluation methods of skin microchannels formation and closure after microneedles application / 药学学报

As a novel transdermal drug delivery technology of minimally invasive, safe and efficient, microneedles have received increasing attention. The microchannels formation by microneedles onto the skin is a prerequisite and key for microneedles to deliver drugs. However, there is still a lack of systematic evaluation in skin microchannels. This review summarized influencing factors and evaluation methods in microchannels formation and healing by microneedles, including geometric parameters, materials for preparation, drugs, penetration parameters, differences among the skin of subjects, and presence or absence of occlusion. This review provides reference for other scholars to further study the effectiveness and security of microneedle applications.

MCP-PMT timing at low light intensities with a DRS4 evaluation board / Estudio de la respuesta temporal de dos MCP-PMT a bajas intensidades de la luz utilizando un DRS4

Abstract Positron emission tomography (PET) is one of the most important diagnostic tools in medicine, allowing three-dimensional imaging of functional processes in the body. It is based on a detection of two gamma rays with an energy of 511 keV originating from the point of annihilation of the positron emitted by a radio-labeled agent. By measuring the difference of the arrival times of both annihilation photons it is possible to localize the tracer inside the body. Gamma rays are normally detected by a scintillation detector, whose timing accuracy is limited by a photomultiplier and a scintillator. By replacing a photo sensor with a microchannel plate PMT (MCP-PMT) and a scintillator with Cherenkov radiator, it is possible to localize the interaction position to the cm level. In a pioneering experimental study with Cherenkov detectors using PbF 2 crystals and microchannel plate photomultiplier tubes MCP-PMT a time resolution better than 100 ps was achieved. In this work a DRS4 digital ring sampler chip was used to read out single photon output signals from two different MCP-PMTs (Hamamatsu R3809 and Burle 85001) with a sampling rate of 5×109 samples/s. The digitized waveforms were analyzed and a comparison between the two detectors timing response was made. The time resolutions achieved were (161 ± 2.21) ps and (220 ± 2.63) ps FWHM for the Hamamatsu and Burle MCP-PMT respectively. No significant variances were observed in the study of the behavior of the FWHM when both MCP-PMT were scanned.

Resumen La tomografía por emisión de positrones (PET) es una importante herramienta en el diagnóstico médico ya que permite la obtención de imágenes tridimensionales de los procesos funcionales en el cuerpo. La técnica está basada en la detección de los dos cuantos gamma de 511 keV originados en la aniquilación del positrón emitido por el radiofármaco administrado al paciente. Midiendo la diferencia en la llegada de los dos cuantos gamma es posible determinar la posición en la que ocurrió la aniquilación. En los equipos convencionales son utilizados detectores centellantes cuya respuesta temporal está limitada por el fotomultiplicador y el cristal centellante. Remplazando el fotomultiplicador por un PMT (MCP-PMT) y el cristal centellante por un detector Cherenkov, es posible localizar la posición en la que ocurrió la aniquilación con una exactitud a nivel de pocos centímetros. En previos resultados experimentales utilizando detectores Cherenkov con cristales de PbF 2 y MCP-PMT se alcanzó una respuesta temporal de menos de 100 ps. En este trabajo fue utilizado un chip DRS4 con una velocidad de procesamiento de las señales de 5×109 samples/s para la lectura de la salida de fotones únicos de los dos MCP-PMT estudiados (Hamamatsu R3809 y Burle 85001). Las señales digitalizadas fueron analizadas y se realizó una comparación entre la respuesta temporal obtenida para ambos MCP-PMT. El tiempo de respuesta obtenido en términos de FWHM fue de (161 ± 2.21) ps y (220 ± 2.63) ps para los MCP-PMT Hamamatsu y Burle respectivamente. No se detectaron variaciones significativas en el FWHM al escanearse la superficie activa de ambos MCP-PMT .

Fabrication of Microchannels and Evaluation of Guided Vascularization in Biomimetic Hydrogels

BACKGROUND: The fabrication of microchannels in hydrogel can facilitate the perfusion of nutrients and oxygen, which leads to guidance cues for vasculogenesis. Microchannel patterning in biomimetic hydrogels is a challenging issue for tissue regeneration because of the inherent low formability of hydrogels in a complex configuration. We fabricated microchannels using wire network molding and immobilized the angiogenic factors in the hydrogel and evaluated the vasculogenesis in vitro and in vivo. METHODS: Microchannels were fabricated in a hyaluronic acid-based biomimetic hydrogel by using “wire network molding” technology. Substance P was immobilized in acrylated hyaluronic acid for angiogenic cues using Michael type addition reaction. In vitro and in vivo angiogenic activities of hydrogel with microchannels were evaluated. RESULTS: In vitro cell culture experiment shows that cell viability in two experimental biomimetic hydrogels (with microchannels and microchannels + SP) was higher than that of a biomimetic hydrogel without microchannels (bulk group). Evaluation on differentiation of human mesenchymal stem cells (hMSCs) in biomimetic hydrogels with fabricated microchannels shows that the differentiation of hMSC into endothelial cells was significantly increased compared with that of the bulk group. In vivo angiogenesis analysis shows that thin blood vessels of approximately 25–30 µm in diameter were observed in the microchannel group and microchannel + SP group, whereas not seen in the bulk group. CONCLUSION: The strategy of fabricating microchannels in a biomimetic hydrogel and simultaneously providing a chemical cue for angiogenesis is a promising formula for large-scale tissue regeneration.

Schwann Cells Enhance Penetration of Regenerated Axons into Three-Dimensional Microchannels

Nerve regeneration after injury requires proper axon alignment to bridge the lesion site and myelination to achieve functional recovery. Transplanted scaffolds with aligned channels, have been shown to induce axon growth to some extent. However, the penetration of axons into the microchannels remain a challenge, influencing the functional recovery of regenerated nerves. We previously demonstrated that the size of microchannels exerts significant impact on Schwann cells (SCs) migration. Here we demonstrate that migration of SCs promotes, significantly, the dorsal root ganglion (DRG) neurons to extend axons into three-dimensional channels and form aligned fascicular-like axon tracts. Moreover, the migrating SCs attach and wrap around the aligned axons of DRG neurons in the microchannels and initiate myelination. The SCs release growth factors that provide chemotactic signals to the regenerating axons, similar to the response achieved with nerve growth factor (NGF), but with the additional capability of promoting myelination, thereby demonstrating the beneficial effects of including SCs over NGF alone in enhancing axon penetration and myelination in three-dimensional microchannels.

Curcumin-loaded Amphiphilic Star-Shaped Polyester-Based Nanoparticles for Drug Delivery System by Microchannels / 中国药学杂志

OBJECTIVE: To prepare the curcumin-loaded amphiphilic star-shaped polyester nanoparticles(Cur-NPs) and evaluate its physicochemical property, toxicity and release behavior in vitro. METHODS: Poly(pentaerythrotol)-poly (ε-Caprolactone)(abbreviated as PET-PCL), a new amphiphilic star-shaped poly ester material, as drug carrier was successfully synthesized by ring-opening polymerization. The toxicity of PET-PCL was determined by MTT method. Drug-loading nanoparticles were prepared by microchannel interface precipitation, and the optimal prescription was screened by single factor experiment. The particle size and the particle dispersion index was measured by dynamic light scattering(DLS) techniques. The encapsulation efficiency and drug loading content were determined by UV spectrophotometry. The in vitro release behavior was investigated by dynamic dialysis. RESULTS: The optimal preparation for nanoparticles was listed as followswater flow rate was 0.5 mL·min-1, lipid phase flow rate was 0.5 mL·min-1, aqueous phase concentration was 1 mg·mL-1, lipid phase concentration was 6.0 mg·mL-1, and drug concentration was 0.6 mg·mL-1. The particle size was (180.3±4.05) nm, the Zeta potential was (-12.1±1.04)mV; drug encapsulation efficiency was (90.12±0.824)%; drug loading content was (4.40±0.080)%; the amount of cumulated drug released in 96 h was (72.89±3.001)%. Survival rate of L929 cells with PET-PCL were (81.05±1.223)%. CONCLUSION: The curcumin-loaded amphiphilic star-shaped polyester nanoparticles prepared by this method are simple and feasible, and have a better controlled release property, have potential application value in the field of drug delivery.

Preparation of Electrochemical Microfluidic Device Based onPulse Driving and Controlling of Microfluids Technique / 分析化学

The fabrication system for the electrochemical microfluidic device was set up based on the pulse driving and controlling of microfluids technology.The nano silver ink and glycerol solution were jetted on the glass substrates to form the microelectrode pattern and the liquid mold pattern for the microchannel.Then the microelectrode and microchannel were obtained through a sintering process and a molding process, respectively.The electrochemical mircrofluidic device was Finally prepared through a bonding process with the microelectrode and the microchannel.The influences of the system parameters on the formation of the droplet were studied, as well as the influences of the droplets diameter and the overlap on the formation of the liquid lines.The minimal width, the thickness and the resistance of the prepared microelectrode were 45 μm, 2.2 μm and 5.2 μΩ cm, respectively.The minimal width of the microelectrode was 35 μm and the surface was smooth.The electrochemical flow detection of glucose concentration was carried out with the device, and the results showed that the glucose concentration had a high linear correlation with the response current, which could be used in the quantitative detection of glucose concentration.The fabrication of the electrochemical microfluidic device based on the pulse driving and controlling of micro fluids technology has many advantages such as simple system structure, lower cost and higher accuracy of the micro droplet and can be used in the preparation of the devices in the biochemical analysis and biosensor areas.

Percutaneous micro-channel approach in treatment of pelvis side cyst and ureteropelvic junction obstruction simultaneously / 中国内镜杂志

Objective To evaluate the efficacy and safety of percutaneous micro-channel approach in treatment of pelvis side cyst and ureteropelvic junction obstruction simultaneously. Methods 32 patients with unilateral solitary parapelvic cyst complicated with UPJO, including 25 cases with ipsilateral kidney stones. After percutaneous holmium laser lithotripsy for patients complicated with calculi, then performed incision and drainage through the channels for parapelvic cyst by holmium laser, and antegrade high pressure balloon dilatation for UPJO, drainage by hippocampal tube in 3 ~ 6 months postoperatively. The operation time of fenestration drainage of cyst, narrow hypertensive dilatation and postoperative hospital stay were analyzed. Results Compared with 1 month (46.17 ± 6.33), 3 months (40.47 ± 6.06), 6 months (33.81 ± 7.05), 9 months (28.95 ± 7.92) after surgery, there was a marked improvement of the separation coefficient of renal convergence, the difference was statistically significant (P < 0.05). And compared with 6 months after surgery, the data of 9 months after surgery has statistical significant differences (P < 0.05). The separation coefficient of renal convergence decreases as time goes on. Conclusions Percutaneous micro-channel approach in treatment of pelvis side cyst and ureteropelvic junction obstruction by the same time can effectively relieve symptoms and decrease the separation coefficient of renal convergence. It is safe and effective.

Advances in Droplet-Based Microfluidics Technology and Its Applications / 分析化学

Micro-droplets are widely used in the fields of drug controlled release,virus detection,synthetic of particulate materials,catalysts and so on due to their small size,large surface area,high speed,high throughput,uniform size,closed system,internal stability and other characteristics.The emergence and development of microfluidics technology provide a new platform for the generation and precise manipulation of size-controlled microdroplets with different structures and functional characteristics.The fundamentals,generation and manipulation of droplet-based microfluidics technology are introduced.Similarities and differences of droplets'conventional preparation methods and droplet-based microfluidics technology are compared and analyzed.Finally,the applications of droplet-based microfluidics for the synthesis of functional materials,bio-medicine and design of food structure etc.are comprehensively presented.In addition,the potential value and development direction of drop-based microfluidics are discussed and forecasted.

A simple microfluidic technology for assaying platelet adhesion and aggregation under physiological flow / 军事医学

Objective To develop a simple microfluidic chip technology for analyzing platelet adhesion and aggregation under the condition of physiological flow .Methods The basic structure of the proposed microfluidic chip was a straight microchannel , where a sample pool and an outlet were located on each side respectively .The fluid dynamic behavior ,of the fluid in the microchannel was analyzed by theoretical calculation and finite element numerical analysis software ANSYS . The microchannel was first coated with type Ⅰ collagen protein.Then,blood flowed through the microchannel at 200 s-1 venous physiological shear rate and 1000 s-1 arterial physiological shear rate respectively .The behavior of the fluorescence labeled platelet adhesion and aggregation was recorded by fluorescence microscopy .Results Theoretical calculation and finite element numerical analysis showed that the microchannel with a width of 700 μm and a height of 70 μm ( aspect ration 10:1 ) had a uniform fluidic shear rate distribution .Compared with those at the 200 s-1 shear rate, the initial adhesion time, aggregation rate and the maximum surface cover rate of the platelet were significantly reduced at the 1000 s-1 shear rate ( P<0.05 ) .At the 1000 s-1 shear rate, tirofiban, an anticoagulant drug , significantly reduced the platelet aggregation in a concentration-dependent manner and the IC 50 was 23.8 nmol/L.Conclusion The technology developed in this paper can dynamically assay platelet adhesion and aggregation under the condition of physiological flow . The proposed microfluidic methods have the advantage of simple implementation and low sample cousumpation , and can be used for point-of-care detection of human platelet function , assay of the efficacy of anticoagulant drugs and for inspection of the thrombin behaviors of small animal models .

A simple microfluidic technology for assaying platelet adhesion and aggregation under physiological flow / 军事医学

Objective To develop a simple microfluidic chip technology for analyzing platelet adhesion and aggregation under the condition of physiological flow .Methods The basic structure of the proposed microfluidic chip was a straight microchannel , where a sample pool and an outlet were located on each side respectively .The fluid dynamic behavior ,of the fluid in the microchannel was analyzed by theoretical calculation and finite element numerical analysis software ANSYS . The microchannel was first coated with type Ⅰ collagen protein.Then,blood flowed through the microchannel at 200 s-1 venous physiological shear rate and 1000 s-1 arterial physiological shear rate respectively .The behavior of the fluorescence labeled platelet adhesion and aggregation was recorded by fluorescence microscopy .Results Theoretical calculation and finite element numerical analysis showed that the microchannel with a width of 700 μm and a height of 70 μm ( aspect ration 10:1 ) had a uniform fluidic shear rate distribution .Compared with those at the 200 s-1 shear rate, the initial adhesion time, aggregation rate and the maximum surface cover rate of the platelet were significantly reduced at the 1000 s-1 shear rate ( P<0.05 ) .At the 1000 s-1 shear rate, tirofiban, an anticoagulant drug , significantly reduced the platelet aggregation in a concentration-dependent manner and the IC 50 was 23.8 nmol/L.Conclusion The technology developed in this paper can dynamically assay platelet adhesion and aggregation under the condition of physiological flow . The proposed microfluidic methods have the advantage of simple implementation and low sample cousumpation , and can be used for point-of-care detection of human platelet function , assay of the efficacy of anticoagulant drugs and for inspection of the thrombin behaviors of small animal models .

A new method for establishing temperature gradient field in micro-channel on glass-PDMS microfluidic chip and for investigating thermal biological effect of cells / 军事医学

Objective To develop a new method for establishing a temperature gradient field in the microchannel on a glass-polydimethylsiloxane ( PDMS ) microfluidic chip and to verify its applicability in the study of cellular thermal biological effect.Methods The establishment and control of the temperature gradient field in the microchannel were implemented by a peripheral indium tin oxide ( ITO) heater and a heating micro-wire embedded in the PDMS chip.The temperature gradient field established in the microchannel was represented by the finite element numerical analysis and temperature-dependent fluorescent dye rhodamine B.Finally, the thermal biological effect, which used cell survival rate of human prostate cancer cells T24 as an indicator, was investigated in the microchannel.Results The results of finite element numerical analysis proved that this method established a temperature gradient field along the length of the microchannel successfully.The distribution range of the temperature gradient field was controlled by the ITO heater, while the gradient of the temperature gradient field was controlled by the heating micro-wire.The measurement result of rhodamine B was identical with the result of the finite element numerical analysis.The thermal biological effect of T24 tumor cell research showed that the cell survival rate decreased with the rise of the regional temperature in the microchannel.Conclusion The method developed in this paper for establishing a temperature gradient field in the microchannel on a glass-PDMS microfluidic chip is simple and easy to implement, and it can be used for parallel study of the cellular thermal biological effect on the microfluidic chip in the future.

Preparation of paclitaxel-loaded PLGA solid lipid nanoparticles in microchannels / 中国药学杂志

OBJECTIVE: To prepare paclitaxel-loaded solid lipid nanoparticles (PTX-SLNs) and evaluate its physicochemical properties, release behavior and antitumor activity in vitro. METHODS: PTX-SLNs were prepared in a rectangular microchannels. The formulation of PTX-SLNs were optimized by the orthogonal design. The particle size distributions was determined by dynamic light scattering(DLS) techniques. The encapsulation efficiency and drug loading content were determined by HPLC. In vitro release behavior and in vitro antitumor activity of the PTX-SLNs were investigated by dialysis and MTT respectively. RESULTS: Transmission electron microscopy (TEM) image showed that the obtained nanoparticles shaped regularly round and dispersed uniformly. The particle size of PTX-SLNs was(129.73 ±2.41) nm, drug loading content and drug encapsulation efficiency were(3.11 ± 1.90)% and(43.67 ± 0.55)% respectively. The in vitro release behavior exhibited that the amount of cumulated paclitaxel released from PTX-SLNs was 87.3% with initial burst release and sustained release in 120 h. In vitro antitumor activity of the PTX-SLNs against human breast cancer MCF-7 indicated that in comparison with paclitaxel solution the minimal inhibitory concentration of paclitaxel-SLNs is remarkably lower. CONCLUSION: PTX-SLNs is easy to prepare in microchannels and its quality is stable. This preparation technique has a very good prospect in the field of pharmaceutics.

Integration of sperm motility and chemotaxis screening with a microchannel-based device / 中华检验医学杂志

Objective Sperm screening is an essential step in IVF procedures. The swim-up method, an assay on sperm motility, is used clinically to select the ideal sperm for subsequent manipulation. However, additional parameters, including acrosome reaction capability, chemotaxis, and thermotaxis are also important indicators of mammalian sperm health. To monitor both sperm motility and chemotaxis simultaneously during sperm screening, we designed and constructed a microdevice comprising a straight channel connected with a bi-branch channel that mimics the mammalian female reproductive tract. Methods The width and length of the straight channel were optimized to select the motile sperm. Cumulus cells were selectively cultured in the bi-branch channel to generate a chemoattractant-forming chemical gradient. Sperm chemotaxis was represented by the ratio of the sperm swimming towards different branches. Results The percentage of motile sperm was improved from ( 58. 5 ± 3. 8 ) % to ( 82. 6±2.9)% by a straight channel 7 mm in length and 1 mm in width. About 10% of sperm were found chemotactically responsive in our experiment, which is consistent with previous studies. Conclusion The combined evaluation of both sperm motility and chemotaxis was achieved for the first time, and the motile and chemotactically responsive sperm can be easily enriched on a lab-on-a-chip device to improve IVF outcome.

Research on RCD of burned rats based on model of silicon microchannels-capillary / 医疗卫生装备

The red cell deformability (RCD) has been taken as a diagnostic aid in recent years. The dilute red cell suspension passes through the silicon microch annels under constant suction pressure. Such three parameters of RCD are measure d as IF (filtration index), and The results show that the above-mentioned parameters can reflect the changes of cell rheological characteristics from dif ferent aspects. With the observation of the flow passage, the rehological charac teristics can be evaluated accurately and comprehensively.