Smurf1-targeting microRNA-136-5p-modified bone marrow mesenchymal stem cells combined with 3D-printed ß-tricalcium phosphate scaffolds strengthen osteogenic activity and alleviate bone defects.

Suitable biomaterials with seed cells have promising potential to repair bone defects. However, bone marrow mesenchymal stem cells (BMSCs), one of the most common seed cells used in tissue engineering, cannot differentiate efficiently and accurately into functional osteoblasts. In view of this, a new tissue engineering technique combined with BMSCs and scaffolds is a major task for bone defect repair. Lentiviruses interfering with miR-136-5p or Smurf1 expression were transfected into BMSCs. The effects of miR-136-5p or Smurf1 on the osteogenic differentiation (OD) of BMSCs were evaluated by measuring alkaline phosphatase activity and calcium deposition. Then, the targeting relationship between miR-136-5p and Smurf1 was verified by bioinformatics website analysis and dual luciferase reporter assay. Then, a rabbit femoral condyle bone defect model was established. miR-136-5p/BMSCs/ß-TCP scaffold was implanted into the defect, and the repair of the bone defect was detected by Micro-CT and HE staining. Elevating miR-136-5p-3p or suppressing Smurf1 could stimulate OD of BMSCs. miR-136-5p negatively regulated Smurf1 expression. Overexpressing Smurf1 reduced the promoting effect of miR-136-5p on the OD of BMSCs. miR-136-5p/BMSCs/ß-TCP could strengthen bone density in the defected area and accelerate bone repair. SmurF1-targeting miR-136-5p-modified BMSCs combined with 3D-printed ß-TCP scaffolds can strengthen osteogenic activity and alleviate bone defects.

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Oil and its pollutants, which enter environment through natural oil seepage and many human activities, have considerable impacts on birds. We summarized the research advances in how oil pollutants influence birds and the cleaning technology of polluted birds and their habitats. The toxicity and destruction to feather structure are the major impacts of oil pollution on birds. Oil pollution can lead to birds' death, and also produce many chronic harms, including causing hemolytic anemia, reducing their immunity, disrupting thermal insulation and waterproo-fing performance of feather. It is an important way to reduce the impacts of oil pollution on birds by timely cleaning up the oil in bird habitats as well as carrying out the clean and repair work to the polluted birds. As a big oil-consuming country, China has been left behind by foreign countries in the studies of the effects of oil pollution on birds. More attention should be paid on the short-term and long-term impacts of oil pollution on birds and the cleaning and remediation technologies of the polluted birds and their habitats.

A Comparative Analysis of Femoral Neck System and Three Cannulated Screws Fixation in the Treatment of Femoral Neck Fractures: A Six-Month Follow-Up.

OBJECTIVE: To investigate the efficacies of Femoral Neck System (FNS) and the three cannulated screws fixation (3CS) as therapeutic options for femoral neck fractures. METHOD: This was a retrospective study involving 69 patients (26 males and 43 females; mean age of 54.9 years (range, 28-66 years)) subjected to either FNS or 3CS for femoral neck fracture therapy. These patients were treated in our hospital from October 2019 to May 2020. Patient follow up was done at 1, 2, 3 and 6 months. During the short-term (6 months) follow-up period, surgical procedures for the two groups and incidences of complications were analyzed. Perioperative parameters were recorded and analyzed. Postoperative hip joint functions were measured and compared using the Harris score. The assessed perioperative parameters included surgical time, hemoglobin loss, fluoroscopy duration, hospitalization length and hospitalization cost. The main complications at last follow-up (6 months) included varus tilting, femoral neck shortness, and implant removal. RESULTS: Differences in the number of patients, age, Garden type of fracture and time from injury to surgery between the two groups were not significant (P > 0.05). With regards to perioperative parameters, compared to 3CS, FNS treatment performed better in surgical time (60.00 ± 12.44 vs 76.81 ± 13.10 min, P = 0.000), blood loss (13.67 ± 8.02 vs 16.58 ± 4.16 g/L, P = 0.059) and fluoroscopy time (39.73 ± 9.57 vs 58.14 ± 9.15 s, P = 0.000). Differences in hospitalization length and cost between the groups were not significant (P > 0.05). During the whole follow-up period, all patients did not exhibit dysfunction, pulmonary embolism or even death as a result of long-term immobilization of affected limbs. Surgical incisions for all patients healed well without infections. During the 6-month follow-up period, the FNS group exhibited a higher Harris score (84.61 ± 3.42 vs 78.67 ± 3.72, p = 0.000). In addition, treatment-associated complications (FNS vs 3CS) included femoral neck varus tilt (3.03% vs 11.11%), femoral neck shortness (6.06% vs 13.89%), and implant removal (0% vs. 13.89%). Implant removal rate for the FNS group was significantly less than that of the 3CS group (P = 0.026). Differences in incidences of femoral neck varus tilt (P = 0.196) and femoral neck shortness (P = 0.282) between the two groups were not significant. However, the difference in number was significant (FNS group was less). CONCLUSION: FNS treatment is associated with a smaller surgical trauma, stronger stability, and reductions in post-operative complication incidences, therefore, it is a potential therapeutic option for femoral neck fractures.

The Trans-Superior Articular Process Approach Utilizing Visual Trephine: A More Time-Saving and Effective Percutaneous Endoscopic Transforaminal Lumbar Discectomy for Migrated Lumbar Disc Herniation.

AIM: To introduce, and to evaluate the efficacy of the trans-superior articular process (trans-SAP) approach utilizing visual trephine in percutaneous endoscopic transforaminal lumbar discectomy (PETLD) for migrated lumbar disc herniation. MATERIAL AND METHODS: This study included 98 patients, 50 patients were in trans-SAP PETLD group and 48 patients were in conventional PETLD group. Visual analogue scale (VAS), Oswestry disability index (ODI), gender, age, blood loss, operation time, the frequency of X-ray fluoroscopy and the percentage of highly migrated herniation were evaluated and compared between the trans-SAP PETLD and conventional PETLD group. RESULTS: In both trans-SAP PETLD and conventional PETLD group, VAS and ODI were decreased at postoperative 1 day and 3 months compared with preoperative (p < 0.001). What's more, the VAS and ODI of postoperative 3 months were lower than postoperative 1 day (p < 0.001). There was no difference in gender, age, blood loss after the operation, and VAS during operation between trans-SAP group and conventional group (p > 0.05). The blood loss during the operation of trans-SAP group was higher (p < 0.05), but the operation time and frequency of X-ray fluoroscopy were lower than conventional group (p < 0.001). Last, trans-SAP group had a higher percentage of highly migrated herniation (p < 0.001). CONCLUSION: Both the conventional way and trans-SAP approach can achieve excellent surgical results. But, in trans-SAP group, the operation time is shorter, and X-ray fluoroscopy is less. PETLD with visual trephine has more advantages in highly migrated herniation and maybe easier to be mastered by young surgeons.

Efficacy-shaping nanomedicine by loading Calcium Peroxide into Tumor Microenvironment-responsive Nanoparticles for the Antitumor Therapy of Prostate Cancer.

Rationale: Prostate cancer has become one of the most threatening malignant tumors in men, leading to an imperative need to develop effective and safe therapies. Because of the unique metabolism of tumor cells, the tumor microenvironment (TME) exhibits distinctive properties compared with normal tissues, among which the pH difference has been utilized as an ideal antitumor strategy. Herein, we introduce a reactive oxygen species (ROS)-controlled-release nanosystem with TME-responsiveness by applying hollow mesoporous silica nanoparticles (HMSNs) as carriers loaded with calcium peroxide (CaO2) and coated with polyacrylic acid (PAA) to construct the functional material CaO2@HMSNs-PAA. The differences in pH values and exogenous ROS scavenging abilities between the tumor tissue and normal tissues and the dual pH-responsiveness from CaO2 and PAA lay a scientific foundation for the application of CaO2@HMSNs-PAA in the tumor-selective therapy for prostate cancer. Methods: The morphology and the structure of the nanosystem were characterized by the transmission electron microscope, scanning electron microscope, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, zeta potential, dynamic light scattering measurement, low-angle X-ray diffraction patterns and nitrogen adsorption/desorption isotherm. The CaO2 loading capacity and release profiles in different buffer solutions were determined by inductively coupled plasma-mass spectrometry. The in vitro intracellular uptake of CaO2@HMSNs-PAA was explored on the PC-3 prostate cancer cell line via confocal laser scanning microscopy. The CCK-8 cell proliferation assay was conducted to evaluate the cytotoxicity of CaO2@HMSNs-PAA against PC-3 cells. ROS produced by CaO2@HMSNs-PAA was observed by a fluorescence microscope. The flow cytometry was utilized to analyze the apoptosis of PC-3 cells induced by CaO2@HMSNs-PAA. The Western blot analysis was performed to detect expressions of critical mitochondria-mediated apoptosis markers in PC-3 cells after incubation with CaO2@HMSNs-PAA. The in vivo biosafety and antitumor efficacy were evaluated out on BALB/c mice and BALB/c nude mice subcutaneously transplanted with PC-3 cells, respectively. Results: Comprehensive characterizations indicated the successful synthesis of CaO2@HMSNs-PAA with significant TME-responsiveness. The experimental results demonstrated that the well-developed nanocarrier could efficiently deliver CaO2 to the tumor site and release ROS in response to the decreased pH value of TME, exerting ideal antitumor effects both in vitro and in vivo by activating the mitochondria-mediated apoptosis pathway. Simultaneously, this nanoplatform caused no detectable damage to normal tissues. Conclusions: After loading into the above nanocomposite, the free CaO2 without a significant antitumor effect can exert excellent antitumor efficacy by responsively releasing ROS under the acidic TME to induce the mitochondria-mediated apoptosis via remarkable oxidative stress and simultaneously minimize damages to normal tissues. The current study presents a new concept of "efficacy-shaping nanomedicine" for the tumor-selective treatment of prostate cancer.

Antibody microarray profiling of osteosarcoma cell serum for identifying potential biomarkers.

The aim of the present study was to identify biomarkers in osteosarcoma (OS) cell serum by antibody microarray profiling, which may be used for OS diagnosis and therapy. An antibody microarray was used to detect the expression levels of cytokines in serum samples from 20 patients with OS and 20 healthy individuals. Significantly expressed cytokines in OS serum were selected when P<0.05 and fold change >2. An enzyme-linked immunosorbent assay (ELISA) was used to validate the antibody microarray results. Finally, classification accuracy was calculated by cluster analysis. Twenty one cytokines were significantly upregulated in OS cell serum samples compared with control samples. Expression of interleukin-6, monocyte chemoattractant protein-1, tumor growth factor-ß, growth-related oncogene, hepatocyte growth factor, chemokine ligand 16, Endoglin, matrix metalloproteinase-9 and platelet-derived growth factor-AA was validated by ELISAs. OS serum samples and control samples were distinguished by significantly expressed cytokines with an accuracy of 95%. The results demonstrated that expressed cytokines identified by antibody microarray may be used as biomarkers for OS diagnosis and therapy.

Preparation of ibuprofen-loaded chitosan films for oral mucosal drug delivery using supercritical solution impregnation.

Drug-loaded chitosan films suitable for oral mucosal drug delivery were prepared using supercritical solution impregnation (SSI) technology. Firstly, chitosan films were obtained via casting method, and the film properties including water-uptake, erosion and mucoadhesive were characterized. SSI process was then employed to load the drug of ibuprofen onto the prepared chitosan films, and the effects of impregnation pressure and temperature on morphologies of the ibuprofen-loaded chitosan films and drug loading capacity (DLC) were studied. The SEM and X-ray diffraction patterns suggested that distinct ibuprofen shapes such as microparticles, flake, rod-like and needle-like occurred after impregnation at different pressures, and DLC varied from 7.9% to 130.4% during the SSI process. The ex vivo release profiles showed that ibuprofen-loaded chitosan films could deliver the drug across the rabbit buccal mucosa, and up to 70% of the ibuprofen was released from the matrix in 460 min. SSI process is a promising method to prepare drug-loaded film formulations for oral mucosal drug delivery, which provides the advantages of low solvent residual and sustained- and controlled- release behavior.

Supercritical fluid assisted production of chitosan oligomers micrometric powders.

Chitosan oligomers (O-chitosan) micrometric particles were produced from aqueous solution using a novel process, i.e. supercritical fluid assisted atomization introduced by hydrodynamic cavitation mixer (SAA-HCM). Hydrodynamic cavitation was introduced to enhance mass transfer and facilitate the mixing between SC-CO2 and liquid solution for fine particles formation. Well defined, separated and spherical microparticles were obtained, and the particles size could be well controlled with narrow distribution ranging from 0.5 µm to 3 µm. XRD patterns showed amorphous structure of O-chitosan microparticles. FTIR, TGA and DSC analyses confirmed that no change in molecular structure and thermal stability after SAA-HCM processing, while the water content was between 5.8% and 8.4%. Finally, tap densities were determined to be below 0.45 g/cm(3) indicating hollow or porous structures of microparticles. By tuning process parameters, theoretical mass median aerodynamic sizes lied inside respirable range of 1-2 µm, which presented the potential of the O-chitosan microparticles in application as inhaled dry powders. SAA-HCM was demonstrated to be very useful in particle size engineering.

Bioactive insulin microparticles produced by supercritical fluid assisted atomization with an enhanced mixer.

Supercritical fluid assisted atomization introduced by a hydrodynamic cavitation mixer (SAA-HCM) was used to micronize insulin from aqueous solution without use of any organic solvents. Insulin microparticles produced under different operating conditions including solution type, solution concentration and precipitator temperature presented distinct morphologies such as highly folded, partly deflated, corrugated or smooth hollow spherical shape. Solution concentration had a striking influence on particle size, and insulin microparticles produced from acidic solution had mean diameters increasing from 1.4 µm to 2.7 µm when protein concentration increased from 3g/L to 50 g/L. HPLC chromatograms showed no degradation of insulin after SAA-HCM processing and FTIR, CD and fluorescence data further confirmed the structural stability. TGA analysis revealed that insulin microparticles remained moderate moisture content compared with raw material. In vivo study showed that insulin processed by SAA-HCM from acidic solution retained identical bioactivity. SAA-HCM is demonstrated to be a very promising process for insulin inhaled formulation development.

Supercritical fluid assisted atomization introduced by an enhanced mixer for micronization of lysozyme: Particle morphology, size and protein stability.

Supercritical fluid assisted atomization introduced by hydrodynamic cavitation mixer (SAA-HCM) was used to produce lysozyme microparticles with controlled particle size distribution in the range for aerosol drug delivery. The process is based on the atomization effect of carbon dioxide. The solubilization of certain amount of carbon dioxide in the solution plays the key role and the HCM can intensify mass transfer between carbon dioxide and liquid feedstock greatly. Water was used as the solvent to solubilize lysozyme and thus no organic residual was detected. The influences of process parameters on particle formation were investigated including temperature in the precipitator, pressure and temperature in the mixer, concentration of the solution and feed ratio CO(2)/solution. The particles were characterized with respect to their morphologies and particle size: well defined, spherical and separated particles with diameters ranging between 0.2 and 5µm could be always produced at optimum operating conditions. Bio-activity assay showed that good activity maintenance of higher than 85% for lysozyme was usually achieved. Solid state characterizations were further performed to investigate the changes of lysozyme in the process. Fourier transform infrared spectroscopy indicated that no change in secondary structure had occurred for processed lysozyme. X-ray diffraction analysis showed that the lysozyme particles produced remained similarly amorphous as the raw material. Differential scanning calorimetry and thermogravimetry analysis revealed that there was no significant difference in water association but with the increase of water content after processing.

Assessment of thyroid function during pregnancy: the advantage of self-sequential longitudinal reference intervals.

INTRODUCTION: To evaluate clinical value of a new self-sequential longitudinal reference intervals of thyroid function during pregnancy. MATERIAL AND METHODS: WE ESTABLISHED TWO DIFFERENT SERIES OF REFERENCE INTERVALS: self-sequential longitudinal reference intervals (SLRI) and general gestation-specific reference intervals (GSRI). For SLRI, the serum of 301 cases were collected five times in every case throughout the gestation. For GSRI, A total of 1455 subjects included in the study. We collected the serum respectively at various trimesters. We used TSH of both reference intervals to screen 1744 pregnant women, and compared the percentage of potential misclassification. RESULTS: Both SLRI and GSRI differed substantially from that for non-pregnant women (p < 0.05). There are similar fluctuations of serum TSH, FT4 and TPO-Ab during normal pregnancy. Although there were no significant differences in most reference intervals between SLRI and GSRI. But the IQR of SLRI were usually smaller than GSRI , especially in 1(st) trimester. Two hundred and fifty two women (14.4%) at various trimesters whose serum TSH concentration was within SLRI would be misclassified, while 23 women (1.3%) with a TSH concentration outside limit would not be identified. 0.11-3.84% women would got thyroid diseases during pregnancy. Subclinical hypothyroidism is most common maternal thyroid disorders. CONCLUSIONS: The SLRI can reflected the changes of thyroid function realistically, and can be used to decrease the percentage of potential misclassification of thyroid dysfunction during pregnancy. Screening for thyroid dysfunction of pregnant women is recommended and important.

Establishment of self-sequential longitudinal reference intervals of maternal thyroid function during pregnancy.

The objective of this study is to establish self-sequential longitudinal reference intervals of thyroid function in normal pregnant women. According to the selection criteria, 301 cases were taken as the normal pregnant population to establish a normal reference range. Meanwhile, 150 healthy women were selected as the normal non-pregnant control group. To establish their own self-sequential longitudinal reference intervals, we collected samples five times in every case throughout the gestation (including first trimester, second trimester, third trimester, prenatal and postpartum), and detected the levels of thyroid stimulating hormone (TSH), free thyroxine (FT4), thyroid peroxidase antibodies (TPO-Ab), and then established the self-sequential longitudinal reference intervals. The levels of TSH, FT4 and TPO-Ab were quantified by electrochemistry immunoassay (ECL) and statistically analyzed using SPSS 13.0 software. Serum TSH of normal pregnant women was at a low level in the first trimester (P < 0.05) and began to rise continuously. Not until prenatal phase was it restored to the non-pregnant state (P > 0.05). During pregnancy, serum FT4 of normal pregnant women were consistently lower than non-pregnant levels (P < 0.05) and kept at low levels. Serum TPO-Ab increased significantly in the third trimester and prenatal phase (P < 0.05). Of normal pregnant women, 6.5% were TPO-Ab positive. In conclusion, the reference intervals in our case will reflect the changes of thyroid function in pregnant women more realistically, resulting in a more accurate value for clinical diagnosis and therapy.

Reference data for quantitative ultrasound values of calcaneus in 2927 healthy Chinese men.

Quantitative ultrasound (QUS) is a bone densitometry technique that is rapidly gaining popularity for the assessment of bone status. However, few QUS data are available for men, especially in China. In the present study, a random stratified sample of 2927 Chinese men (10-90 years) was recruited, and bone status was established using measurements by Achilles ultrasonometer. The peak stiffness index (SI) value for Chinese men was 103.0 +/- 20.8, which presented in the age group of 20-24 years. Pearson correlation analysis showed that there was significant correlation between SI and age (P < 0.001), and multivariate regression analysis indicated that weight was also an important factor for SI. In addition, in comparison with the normal data of Italian and Japanese males, the SI value for Chinese males in each age group was lower than those of Italians but higher than Japanese, except for the 20-29 years age group. The descending velocity of curves for Chinese men was lower than that of Italian and Japanese men. In conclusion, QUS values of the calcaneus provided by the present study may be used as normal reference values for Chinese men.

Crucial roles of GATA-2 and SP1 in adrenomedullin-affected expression of tissue factor pathway inhibitor in human umbilical vein endothelial cells exposed to lipopolysaccharide.

Adrenomedullin (ADM) is a vasodilator peptide that has a variety of effects, including antithrombotic activities and resistant roles to lipopolysaccharide (LPS)-induced septic shock. During sepsis, LPS triggers the development of disseminated intravascular coagulation (DIC) via the tissue factor-dependent pathway of coagulation. It is unknown whether the antithrombotic activities of ADM contribute to its resistance to sepsis. In the present study, we investigated the effects of ADM on tissue factor pathway inhibitor (TFPI) (primary anticoagulant factor) expression in human umbilical vein endothelial cells (HUVECs) exposed to LPS, and the possible underlying mechanism for these effects. Exposure of HUVECs to LPS for 12 hours caused significant decrease of TFPI protein activities and mRNA expression. These effects were abolished by treatment with ADM (10(-10) to 10(-6) M), cAMP analogue and calcium antagonist. Accordingly, cAMP antagonist inhibited the counteraction effect of ADM on LPS in TFPI expression. Electrophoresis mobility shift assay (EMSA) and Western blot analysis showed that the protein level of GATA-2 and SP1 transcriptional factors and their binding to the corresponding regulatory sequences decreased by LPS treatment. And these effects of LPS were antagonized by ADM. Promoter-reporter assays and mutational analysis also confirmed the roles of GATA-2 and SP1 motifs from -1247 to -381 bp promoter sequence in TFPI inducible expression. Taken together, these results indicate that ADM antagonizes the effect of LPS on TFPI expression, which is mediated by affecting transcriptional factor GATA-2 and SP1 through cAMP and calcium signaling pathway.

[Ultrasonic bone mineral density of calcaneus in 1 816 healthy subjects in Guangxi autonomous region].

OBJECTIVE: To study the relationship between ultrasonic bone mineral density (BMD) of calcaneus and age, height, and body weight, and to establish the normal reference value for stiffness index (SI) of healthy subjects in Guangxi autonomous region and provide scientific foundation for the diagnosis and prevention of osteoporosis. METHODS: SI of calcaneus in 1 816 healthy adults aged 11-90 years (775 men, 1 041 women) were measured with quantitative ultrasound. According to their ages, all the men and women were divided into 13 groups by 5-year age group. RESULTS: SI reached peak values in 21-25 year group in men (range: 111.45 +/- 21.19) and in 16-20 year group in women (range: 101.26 +/- 17.51). Then the SI value began to decline with aging. The SI featured by a typical dual-peak curve in women and the decrease rate of SI was faster in women than in men over 61 years. Multivariate linear regression analysis showed significantly negative correlation between SI and age (P < 0.001), positive correlation between SI and body weight (P < 0.05 for men; P < 0.01 for women), and positive correlation between SI and height in women (P < 0.01). CONCLUSION: SI correlates with age, height, and weight. The acquired SI value may provide a reference for the diagnosis of osteoporosis.

[Bone density of calcaneus of 2769 healthy persons in Zhejiang province].

OBJECTIVE: To provide a scientific basis for the diagnosis and prevention of osteoporosis in Chinese populations. METHODS: The stiffness index (STI) of the calcaneus was measured with the Achilles Express ultrasound apparatus made in USA among 2769 healthy persons, 1262 males and 1507 females, aged 10 to over 60, in Zhejiang province. The relationships between the STI and sex and age were analyzed. RESULTS: The peak STI appeared in the age 20 - 24 among the males, and appeared in the age 15 - 19 among the females. Beyond these age periods the STI decreased along with the age. The STI values of the males aged over 54 were significantly higher than those of the females the same age. The speed of STI decrease of the females aged over 55 was higher than the males of the same age (P < 0.01). The prevalence of osteoporosis was higher in the females than in the males. The STI was negatively correlated with age, and positively correlated with height and body weight in both sexes. The practically measured T values were mostly significantly lower than the instrument' T values (with young adult Japanese as reference population). CONCLUSION: There are significant relationships between STI and age, height, and body weight in both males and females. The distribution of bone mineral density of the reference population for the imported instrument does not completely accord with that of Chinese. It is necessary to establish a standard adaptable to the specific condition of Chinese.

Optimization of technological conditions for one-pot synthesis of (S)-alpha-cyano-3-phenoxybenzyl acetate in organic media.

Optically active form of alpha-cyano-3-phenoxybenzyl (CPB) alcohol, building block of pyrethroid insecticides, was synthesized as its acetate by the combination of anion-exchange resin (D301)-catalyzed transcyanation between m-phenoxybenzaldehyde (m-PBA) and acetone cyanohydrin (AC), and lipase (from Alcaligenes sp.)-catalyzed enantioselective transesterification of the resulting cyanohydrin with vinyl acetate. Through optimizing technological conditions, the catalyzing efficiency was improved considerably compared to methods previously reported. Concentrations of CPB acetate were determined by gas chromatograph. The enantio excess (e.e.) values of CPB acetate were measured by NMR (nuclear magnetic resonance) method. Effects of solvents and temperatures on this reaction were studied. Cyclohexane was shown to be the best solvent among the three tested solvents. 55 degrees C was the optimal temperature for higher degree of conversion. External diffusion limitation was excluded by raising the rotational speed to 220 r/min. However, internal diffusion could not be ignored, since the catalyst (lipase) was an immobilized enzyme and its particle dimension was not made small enough. The reaction rate was substantially accelerated when the reactant (m-PBA) concentration was as high as 249 mmol/L, but decreased when the initial concentration of m-PBA reached to 277 mmol/L. It was also found that the catalyzing capability of recovered lipase was high enough to use several batches. Study of the mole ratio of AC to m-PBA showed that 2:1 was the best choice. The strategy of adding base catalyst D301 was found to be an important factor in improving the degree of conversion of the reaction from 20% to 80%. The highest degree of conversion of the reaction has reached up to 80%.

Simultaneous assay of glucose, lactate, L-glutamate and hypoxanthine levels in a rat striatum using enzyme electrodes based on neutral red-doped silica nanoparticles.

An electrochemical method suitable for the simultaneous measurement of cerebral glucose, lactate, L-glutamate and hypoxanthine concentrations from in vivo microdialysis sampling has been successfully performed for the first time using a neutral red-doped silica (NRDS) nanoparticle-derived enzyme sensor system. These uniform NRDS nanoparticles (about 50 +/- 3 nm) were prepared by a water-in-oil (W/O) microemulsion method, and characterized by a TEM technique. The neutral red-doped interior maintained its high electron-activity, while the exterior nano-silica surface prevented the mediator from leaching out into the aqueous solution, and showed high biocompability. These nanoparticles were then mixing with the glucose oxidase (GOD), lactate oxidase (LOD), L-glutamate oxidase (L-GLOD) or xanthine oxidase (XOD), and immobilized on four glassy carbon electrodes, respectively. A thin Nafion film was coated on the enzyme layer to prevent interference from molecules such as ascorbic acid and uric acid in the dialysate. The high sensitivity of the NRDS modified enzyme electrode system enables the simultaneous monitoring of trace levels of glucose, L-glutamate, lactate and hypoxanthine in diluted dialysate samples from a rat striatum.